KEPCO®
THE POWER SUPPLIER™
OPERATOR’S MANUAL
BHK-MG FULL RACK SERIES
VOLTAGE/CURRENT-STABILIZED DC SOURCE
KEPCO INC.
An ISO 9001 Company.
POWER SUPPLY
MODELS
BHK 300-0.6MG
BHK 500-0.4MG
BHK 1000-0.2MG
BHK 2000-0.1MG
IMPORTANT NOTES:
1) This manual is valid for the following Model and associated serial numbers:
MODEL SERIAL NO. REV. NO.
2) A Change Page may be included at the end of the manual. All applicable changes and
revision number changes are documented with reference to the equipment serial numbers. Before using this Instruction Manual, check your equipment serial number to identify
your model. If in doubt, contact your nearest Kepco Representative, or the Kepco Documentation Office in New York, (718) 461-700 0, requestin g the correct revision for your par ticular model and serial number.
3) The contents of this manual are protected by copyright. Reprodu ction of any part can be
made only with the specific written permission of Kepco, Inc.
Data subject to change without notice.
©2016, KEPCO, INC
P/N 243-1322j
KEPCO, INC. 131-38 SANFORD AVENUE FLUSHING, NY. 11355 U.S.A. TEL (718) 461-7000 FAX (718) 767-1102
email: hq@kepcopower.com World Wide Web: http://www.kepcopower.com
228-1782 Dec of Conf BHK-MG 40W (1/2 Rack), 200W (Full Rack)
A
Declaration of Conformity
Application of Council directives:
2006/95/EC (LVD)
2004/108/EC (EMC
Standard to which Conformity is declared:
IEC61010-1, 3rd Edition Safety requirements for electrical equipment for
measurement, control, and laboratory use
(designed to meet)
EN55011 (Class A, conducted and radiated)
(radiated is designed to meet)
Limits and Methods of Measurement of Radio
Disturbance Characteristics of Information
Technology Equipment (designed to meet)
EN61000-4-11, EN61000-4-4, EN61000-4-2,
EN61000-4-5, IEC61000-4-3, IEC61000-4-6,
IEC61000-4-8
Voltage Dips, Fast Transient_EFT,
ESD, Surge Immunity, Radiated Immunity
(designed to meet), Conducted Immunity,
Magnetic Field Immunity (designed to meet)
Manufacturer's Name:
Manufacturer's Address:
KEPCO, INC.
131-38 SANFORD AVENUE
FLUSHING NY 11355
USA
Importer's Name:
Importer's Address:
Type of Equipment:
Component Power Supply
Model Series
BHK-MG 40W (1/2 Rack), 200W
(Full Rack), all models, all
options
Model No.:
Year of Manufacture:
I, the undersigned, declare that the product specified above, when used in
conjunction with the conditions of conformance set forth in the product
instruction manual, complies with the requirements of the Low Voltage Directive
2006/95/EC, which forms the basis for application of the CE Mark to this
product.
Place: Kepco, Inc.
131-38 Sanford Ave.
Flushing NY 11355
USA
Date:
Mark Kupferberg
(Full Name)
Executive Vice President
(position)
032816
Conditions of Conformance
When this product is used in applications governed by the requirements of the EEC, the following restrictions and conditions apply:
1. For European applications, requiring com plian c e to the Low Voltage Directive, 73/23/EEC, this power
supply is considered a component product, designed for “built in“ applications. Because it is incomplete in construction, the end product enclosure must provide for compliance to any remaining electrical safety requirements and act as a fire enclosure. (EN61010-1:2001, Cl. 6, Cl. 7, Cl.8, and Cl. 9)
2. This power supply is designed for stationary installation, with mains power applied via a detachable
power supply cord or via direct wiring to the source power terminal block.
3. This power supply is considered a Class 1 (earthed) product. It is intended for use as part of equipment meant for test, measurement and laboratory use, and is designed to operate from single phase,
three wire power systems. This equipment must be installed within a suitably wired equipment rack,
utilizing a three wire (grounded) mains connection. See wiring section of this manual for complete
electrical wiring instructions. (EN61010-1:2001, Cl.6.10.1)
4. This power supply has secondary output circuits that are considered hazardous, and which exceed
240 VA at a potential of 2V or more.
5. The output wiring terminals of this power supply has not been evaluated for field wiring a nd, th erefore ,
must be properly configured by the end product manufacturer prior to use.
6. This power supply employs a supplementary circuit protector in the form of a circuit breaker mounted
on the front panel. This circuit breaker protects the power supply itself from damage in the event of a
fault condition. For complete circuit protection of the end product, as well as the building wiring, it is
required that a primary circuit protection device be fitted to the branch circuit wiring. (EN61010-1:2001,
Cl. 9.5)
7. Hazardous voltages are present within this power supply during normal operation. All operator adjustments to the product are made via externally accessible switches, controls and signal lines as specified within the product operating instructions. There are no user or operator serviceable parts within
the product enclosure. Refer all servicing to qualified and trained Kepco service technicians.
B 228-1351 COND/CONFORM 032816
SAFETY INSTRUCTIONS
!
!
!
!
!
1. Installation, Operation and Service Precautions
This product is designed for use in accordance with EN 61010-1 and UL 3101 for Installation Category 2,
Pollution Degree 2. Hazardous volt age s ar e p rese nt wi th in this p roduct du ring no rmal o per ation. The pr oduct should never be operated with the cover removed unless equivalent protection of the operator from
accidental contact with hazardous internal voltages is provided:
There are no operator serviceable part s or adjustment s within the product enclosure.
Refer all servicing to trained service technician.
Source power must be removed from the product prior to performing any servicing.
This product is factory set for the nominal a-c mains voltage indicated by the Voltage
Range Selector switch located adjacent to the source power connection on the product's rear panel. To reconfigure the product input for other nominal mains voltages as
listed herein, follow the applicable instructions shown in this manual.
NOTE: Source power must be removed from the product prior to changing the setting of the Voltage Range Selector switch.
2. Grounding
This product is a Class 1 device which utilizes protective earthing to ensure operator safety.
The PROTECTIVE EARTHING CONDUCTOR TERMINAL must properly connected prior to application of source power to the product (see instructions on installation herein) in order to ensure safety from electric shock.
PROTECTIVE EARTHING CONDUCTOR TERMINAL - This symbol indicates the
point on the product to which the protective earthing conductor must be attached.
EARTH (GROUND) TERMINAL - This symbol is used to indicate a point which is
connected to the PROTECTIVE EARTHING TERMINAL. The component installer/
assembler must ensure that this point is connected to the PROTECTIVE EARTHING TERMINAL.
CHASSIS TERMINAL -This symbol indicates frame (chassis) connection, which is
supplied as a point of convenience for performance purposes (see instructions on
grounding herein). This is not to be confused with the protective earthing point, an d
may not be used in place of it.
3. Electric Shock Hazards
This product outputs hazardous voltage and energy levels as a function of normal operation. Operators
must be trained in its use and exercise ca ution as well a s common sense during use to prevent a ccidental
shock.
This symbol appears adjacent to any external te rminals at wh ich haza rdous volt age
levels as high as 500V d-c may exist in the course of normal or single fault conditions.
This symbol appears adjacent to any external te rminals at wh ich haza rdous volt age
levels in excess of 500V d-c may exist in the course of normal or single fault conditions
228-1353 SAFETY - (SWITCH) 032816 C/(D BLANK)
TABLE OF CONTENTS
SECTION PAGE
SECTION 1 - INTRODUCTION
1.1 Scope of Manual ..................................................................................................................................... 1-1
1.2 General Description................................................................................................................................. 1-1
1.3 Specifications.......................................................................................................................................... 1-1
1.4 Features.................................................................................................................................................. 1-8
1.4.1 Local Control...................................................................................................................................... 1-8
1.4.2 Remote Control.................................................................................................................................. 1-8
1.4.2.1 Digital Programming .................................................................................................................... 1-8
1.4.2.2 Analog Programming................................................................................................................... 1-8
1.4.2.3 Analog Readback......................................................................................................................... 1-8
1.4.3 Digital Calibration............................................................................................................................... 1-8
1.4.4 Overvoltage/Overcurrent Protection.................................................................................................. 1-9
1.4.5 User-defined Voltage/Current Limits.................................................................................................. 1-9
1.4.6 Nonvolatile Storage of Programmed Sequences or Active Settings.................................................. 1-10
1.4.7 Current Scale..................................................................................................................................... 1-10
1.4.8 Fast Mode/Slow Mode Selection....................................................................................................... 1-10
1.4.9 External Trigger Port.......................................................................................................................... 1-10
1.4.10 Built-in Protection............................................................................................................................... 1-11
1.4.11 Current Sink Capability...................................................................................................................... 1-12
1.4.12 Analog Readback and Flag Signals Available for Customer Use...................................................... 1-12
1.5 Equipment Supplied................................................................................................................................ 1-13
1.6 Accessories............................................................................................................................................. 1-14
1.7 Safety...................................................................................................................................................... 1-14
SECTION 2 - INSTALLATION
2.1 Unpacking and Inspection....................................................................................................................... 2-1
2.2 Terminations and Controls...................................................................................................................... 2-1
2.3 Source Power Requirements .................................................................................................................. 2-6
2.4 Cooling.................................................................................................................................................... 2-6
2.5 Preliminary Operational Check................................................................................................................ 2-6
2.6 Installation............................................................................................................................................... 2-8
2.6.1 Bench Top Use.................................................................................................................................. 2-8
2.6.2 Rack Mounting................................................................................................................................... 2-8
2.7 Wiring Instructions................................................................................................................................... 2-8
2.7.1 Safety Grounding............................................................................................................................... 2-8
2.7.2 Source Power Connections............................................................................................................... 2-9
2.7.3 D-C Output Grounding....................................................................................................................... 2-9
2.7.4 Power Supply/Load Interface............................................................................................................. 2-9
2.7.4.1 Cable Recommendations............................................................................................................. 2-10
2.7.5 Load Connection - General................................................................................................................ 2-10
2.7.5.1 Local Sensing/Remote Sensing Select........................................................................................ 2-11
2.7.5.2 Fast Mode/Slow Mode Select...................................................................................................... 2-11
2.7.5.3 Grounding Network Configuration................................................................................................ 2-11
2.7.5.4 Positive Output, Negative Terminal Grounded ............................................................................ 2-11
2.7.5.5 Negative Output, Positive Terminal Grounded ............................................................................ 2-12
2.8 Operating Configuration.......................................................................................................................... 2-13
2.9 Status Port............................................................................................................................................... 2-13
SECTION 3 - OPERATION
3.1 General.................................................................................................................................................... 3-1
3.2 Local Mode Operation............................................................................................................................. 3-1
3.2.1 Front Panel Keypad and LCD............................................................................................................ 3-1
3.2.1.1 Command Entry Status................................................................................................................ 3-1
3.2.1.2 Data Entry Status......................................................................................................................... 3-1
3.2.1.3 Display (LCD)............................................................................................................................... 3-1
3.2.1.4 Keypad Functions........................................................................................................................ 3-2
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3.2.2 Turning the Power Supply On........................................................................................................... 3-4
3.2.3 Error Conditions................................................................................................................................ 3-5
3.2.4 Setting Local Mode........................................................................................................................... 3-5
3.2.5 Adjusting LCD Contrast ..................................... ... .................................................. ... ....................... 3-6
3.2.6 Enabling/Disabling Audible Beeps.................................................................................................... 3-6
3.2.7 Enabling/Disabling DC Output Power............................................................................................... 3-6
3.2.7.1 Disabling DC Output when using Digital Inputs only (keypad and/or GPIB) ............................... 3-6
3.2.7.2 Disabling DC Output when using Analog control. ....................................................................... 3-6
3.2.7.3 Remote Shutdown using External Trigger Port........................................................................... 3-7
3.2.7.4 Power Up DC Output Control...................................................................................................... 3-7
3.2.8 Reset Operation ................................................................................................................................ 3-7
3.2.8.1 Setting Power-Up & Reset Current ............................................................................................. 3-7
3.2.9 Setting Output Voltage or Current..................................................................................................... 3-8
3.2.10 Changing Current Scale.................................................................................................................... 3-8
3.2.11 Setting Overvoltage or Overcurrent Protection................................................................................. 3-9
3.2.12 Changing Maximum Voltage or Current Value ................................................................................. 3-10
3.2.13 Storing Power Supply Output Settings.............................................................................................. 3-10
3.2.14 Recalling Stored Output Settings...................................................................................................... 3-11
3.2.15 Firmware Version .............................................................................................................................. 3-11
3.2.16 Local Mode Programming of the Power Supply................................................................................ 3-11
3.2.16.1 Creating or Modifying a Program (Program Edit Mode).............................................................. 3-11
3.2.16.1.1 Modifying Programmed Time Interval..................................................................................... 3-12
3.2.16.1.2 Time Interval Accuracy...........................................................................................................3-12
3.2.16.2 Running a Program..................................................................................................................... 3-12
3.2.16.3 Stepping Through a Program...................................................................................................... 3-12
3.2.16.4 Cycling a Program....................................................................................................................... 3-14
3.2.16.5 Running a Program Once ................................................................................................
3.2.16.6 Stopping a Running Program............................................. ... ...................................................... 3-14
3.2.16.7 Sample Program......................................................................................................................... 3-14
3.2.17 Calibration ......................................................................................................................................... 3-15
3.3 Remote Mode Programming Using SCPI commands via IEEE 488 (GPIB). Bus .................................. 3-15
3.3.1 IEEE 488 (GPIB) Bus Protocol ......................................................................................................... 3-15
3.3.2 DCL Control...................................................................................................................................... 3-17
3.3.3 Changing the GPIB Address............................................................................................................. 3-17
3.3.4 External Trigger ................................................................................................................................ 3-17
3.3.5 BHK-MG VISA Instrument driver ........................................ ... ........................................................... 3-18
3.3.6 Programming Techniques to Optimize performance ........................................................................ 3-18
3.3.6.1 Programming Voltage/Current Limit and Current/Voltage Limit.................................................. 3-18
3.3.6.2 Making Sure the Previous Command is Complete ..................................................................... 3-19
3.4 RS232-C Operation................................................................................................................................ 3-20
3.4.1 Setting RS 232 Baud Rate................................................................................................................ 3-21
3.4.2 Serial Interface.................................................................................................................................. 3-21
3.4.3 RS 232 Implementation .................................................................................................................... 3-21
3.4.3.1 Echo Mode.................................................................................................................................. 3-22
3.4.3.2 Prompt Method............................................................................................................................ 3-22
3.4.3.3 XON XOFF Method..................................................................................................................... 3-22
3.4.4 Isolating RS 232 Communication Problems ..................................................................................... 3-23
3.5 SCPI Programming................................................................... .............................................................. 3-23
3.5.1 SCPI Messages ................................................................................................................................ 3-23
3.5.2 Common Commands/Queries .......................................................................................................... 3-24
3.5.3 SCPI Subsystem Command/Query Structure...................................................................................
3.5.3.1 ABORt Subsystem...................................................................................................................... 3-24
3.5.3.2 INITiate Subsystem..................................................................................................................... 3-24
3.5.3.3 LIST Subsystem.......................................................................................................................... 3-24
3.5.3.4 MEASure Subsystem.................................................................................................................. 3-24
3.5.3.5 OUTPut Subsystem .................................................................................................................... 3-24
3.5.3.6 Instrument Subsystem ................................................................................................................ 3-24
........... 3-14
3-24
ii BHK 500-0.4MG SVC 032816
TABLE OF CONTENTS
SECTION PAGE
3.5.3.7 STATus Subsystem..................................................................................................................... 3-25
3.5.3.8 System Subsystem...................................................................................................................... 3-25
3.5.3.9 TRIGger subsystem..................................................................................................................... 3-25
3.5.3.10 [SOURce:]VOLTage and [SOURce:]CURRent Subsystems....................................................... 3-25
3.5.3.11 CALibrate Subsystem.................................................................................................................. 3-25
3.5.4 Program Message Structure.............................................................................................................. 3-25
3.5.4.1 Keyword....................................................................................................................................... 3-26
3.5.4.2 Keyword Separator...................................................................................................................... 3-26
3.5.4.3 Query Indicator............................................................................................................................ 3-26
3.5.4.4 Data ............................................................................................................................................. 3-27
3.5.4.5 Data Separator............................................................................................................................. 3-27
3.5.4.6 Message Unit Separator.............................................................................................................. 3-27
3.5.4.7 Root Specifier .............................................................................................................................. 3-29
3.5.4.8 Message Terminator.................................................................................................................... 3-29
3.5.5 Understanding The Command Structure........................................................................................... 3-29
3.5.6 Program Message Syntax Summary................................................................................................. 3-30
3.5.7 SCPI Program Examples................................................................................................................... 3-30
3.6 Remote Programming Using Analog Programming Terminals................................................................ 3-31
3.6.1 Analog Programming Warnings and Cautions................................................................................... 3-33
3.6.2 Programming with external resistance............................................................................................... 3-35
3.6.2.1 Voltage Mode............................................................................................................................... 3-37
3.6.2.2 Current Mode............................................................................................................................... 3-37
3.6.3 Programming with external voltage using a low impedance Voltage source..................................... 3-38
3.6.3.1 Voltage Mode............................................................................................................................... 3-42
3.6.3.2 Current Mode............................................................................................................................... 3-43
3.6.4 Programming with external voltage using a high impedance, low level (1V) Voltage source............ 3-43
3.6.4.1 Voltage Mode...........................................................................................................
3.6.4.2 Current Mode............................................................................................................................... 3-46
3.6.5 Programming with external current source (1 mA) ............................................................................ 3-47
3.6.5.1 Voltage Mode............................................................................................................................... 3-49
3.6.5.2 Current Mode............................................................................................................................... 3-49
3.7 Operating Modes..................................................................................................................................... 3-50
3.7.1 Slow/Fast mode of operation............................................................................................................. 3-50
3.7.2 Series operation................................................................................................................................. 3-52
3.7.2.1 Automatic series operation.......................................................................................................... 3-53
3.7.2.2 Master-slave series operation (Automatic Tracking).................................................................... 3-56
3.7.2.2.1 Voltage Mode Operation.........................................................................................................3-56
3.7.2.2.2 Current Mode Operation .........................................................................................................3-59
3.7.3 Parallel operation............................................................................................................................... 3-61
3.7.3.1 Automatic parallel operation ........................................................................................................ 3-62
3.7.3.2 Master-slave parallel operation.................................................................................................... 3-64
3.7.3.2.1 Voltage Mode Operation.........................................................................................................3-65
3.7.3.2.2 Current Mode Operation .........................................................................................................3-67
.................... 3-46
SECTION 4 - CALIBRATION
4.1 General.................................................................................................................................................... 4-1
4.2 Equipment Required................................................................................................................................ 4-1
4.3 Calibration Procedures Using Front Panel Keypad................................................................................. 4-1
4.3.1 Voltage Calibration ............................................................................................................................ 4-2
4.3.2 High Current Calibration.................................................................................................................... 4-3
4.3.3 Low Current Calibration..................................................................................................................... 4-4
4.4 Calibration Using IVI Driver..................................................................................................................... 4-5
4.4.1 Setup ................................................................................................................................................. 4-5
4.4.2 Main Control Panel............................................................................................................................ 4-6
BHK 500-0.4MG SVC 020498 iii
TABLE OF CONTENTS
SECTION PAGE
4.4.3 Calibration Controls .......................................................................................................................... 4-6
4.4.4 Calibration Procedure....................................................................................................................... 4-7
4.5 Changing the Calibration Password ....................................................................................................... 4-10
4.6 Restoring Previous Calibration Values................................................................................................... 4-11
4.7 Restoring Factory Calibration Values..................................................................................................... 4-11
4.8 Calibration Storage................................................................................................................................. 4-11
APPENDIX A - IEEE 488.2 COMMAND/QUERY DEFINITIONS
A-1 Introduction................................................................................................ .. ........................................... A-1
A.2 *CLS — Clear Status Command ............................................................................................................ A-1
A.3 *ESE — Standard Event Status Enable Command................................................................................ A-1
A.4 *ESE? — Standard Event Status Enable Query..................................................................................... A-1
A.5 *ESR? — Event Status Register Query.................................................................................................. A-2
A.6 *IDN? — Identification Query.................................................................................................................. A-2
A.7 *OPC — Operation Complete Command ............................................................................................... A-2
A.8 *OPC? — Operation Complete Query.................................................................................................... A-2
A.9 *RCL — Recall Command.................................... ... ................................................ .. ... .......................... A-2
A.10 *RST — Reset Command..................................... ... ............................................................................... A-3
A.11 * SAV — Save Command....................................................................................................................... A-3
A.12 *SRE — Service Request Enable Command......................................................................................... A-4
A.13 *SRE? — Service Request Enable Query.............................................................................................. A-4
A.14 *STB? — Status Byte Register Query.................................................................................................... A-4
A.15 *TRG — Trigger Command.................................................................................................................... A-4
A.16 *TST? — Self Test Query....................................................................................................................... A-4
APPENDIX B - SCPI COMMAND/QUERY DEFINITIONS
B-1 Introduction................................................................................................ .. ........................................... B-1
B.2 Numerical Values.................................................................................................................................... B-2
B.3 ABORt Command................................ ................................................ ... ................................................ B-2
B.4 CAL Commands and Queries................................................................................................................. B-2
B.5 DISPlay:CONTrast Command.............................. ... ............................................................................... B-2
B.6 DISPlay:CONTrast? Query......................................... ... .. ................................................ ... .................... B-2
B.7 DISPlay:MODE Command ................................................................................... ... ............................... B-4
B.8 DISPlay:MODE? Query ................................................... ................................................ ... .................... B-4
B.9 DISPlay:TEXT Command.................................. ... ................................................... ............................... B-4
B.10 DISPlay:TEXT? Query........................................................... ... ... ...................................... . .................... B-4
B.11 INITiate[:IMMediate] Command............................................................................................... ............... B-4
B.12 INITiate:CONTinuous Command............................................................................................................ B-4
B.13 INITiate:CONTinuous? Query................................................................................................................. B-4
B.14 INSTrument:STATe Command............................................................................................................... B-5
B.15 INSTrument:STATe? Query ................................................................................................................... B-5
B.16 [SOURce:]LIST:CLEar Command................................... ... ... .................................................. ............... B-5
B.17 [SOURce:]LIST:COUNt Command............................................................ .. ... .................................. ... ... B-5
B.18 [SOURce:]LIST:COUNt? Query............................... ... ............................................... ... ... ....................... B-5
B.19 [SOURce:]LIST:COUNt:SKIP Command.................................. .................................................. ............ B-5
B.20 [SOURce:]LIST:COUNt:SKIP? Query .................................................... .......................................... ... ... B-5
B.21 [SOURce:]LIST:CURRent Command..................................................................................................... B-5
B.22 [SOURce:]LIST:CURRent? Query.......................................................................................................... B-6
B.23 [SOURce:]LIST:CURRent:POINts? Query ............................................................................................. B-6
B.24 [SOURce:]LIST:DIRection Command................................. ................................................... ................. B-6
B.25 [SOURce:]LIST:DIRection? Query ................................................... ............................................. ......... B-6
B.26 [SOURce:]LIST:DWELl Command................................ .. ....................................................................... B-6
B.27 [SOURce:]LIST:DWELl? Query............................................. ... ... ........................................................... B-6
B.28 [SOURce:]LIST:DWELl:POINts? Query ...................................................... ........................................... B-6
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B.29 [SOURce:]LIST:QUERy Command........................................................................................................ B-7
B.30 [SOURce:]LIST:QUERy? Query............................................................................................................. B-7
B.31 [SOURce:]LIST:VOLTage Command..................................................................................................... B-7
B.32 [SOURce:]LIST:VOLTage? Query ......................................................................................................... B-7
B.33 [SOURce:]LIST:VOLTage:POINts? Query............................................................................................ . B-7
B.34 MEASure[:SCALar]:CURRent[:DC]? Query........................................................................................... B-9
B.35 MEASure:VOLTage[:SCALar][:DC]? Query........................................................................................... B-9
B.36 OUTPut[:STATe] Command................................................................................................................... B-9
B.37 OUTPut[:STATe]? Query ....................................................................................................................... B-9
B.38 [SOURce:]CURRent[:LEVel][:IMMediate][:AMPlitude] Command.......................................................... B-10
B.39 [SOURce:]CURRent[:LEVel][:IMMediate][:AMPlitude]? Query .............................................................. B-10
B.40 [SOURce:]CURRent:LIMit[:HIGH] Command......................................................................................... B-10
B.41 [SOURce:]CURRent:LIMit[:HIGH]? Query ............................................................................................. B-10
B.42 [SOURce:]CURRent:MODE Command.................................................................................................. B-10
B.43 [SOURce:]CURRent:MODE? Query ...................................................................................................... B-11
B.44 [SOURce:]CURRent:PROTection[:LEVel] Command............................................................................ B-11
B.45 [SOURce:]CURRent:PROTection[:LEVel]? Query................................................................................. B-11
B.46 [SOURce:]CURRent:RANGe Command................................................................................................ B-11
B.47 [SOURce:]CURRent:RANGe? Query..................................................................................................... B-11
B.48 [SOURce:]CURRent[:LEVel]:TRIGgered[:AMPlitude] Command........................................................... B-11
B.49 [SOURce:]CURRent[:LEVel]:TRIGgered[:AMPlitude]? Query ............................................................... B-12
B.50 [SOURce:]VOLTage[:LEVel][:IMMediate][:AMPlitude] Command........................................... ............... B-12
B.51 [SOURce:]VOLTage[:LEVel][:IMMediate][:AMPlitude]? Query............................ .. ................................ B-12
B.52 [SOURce:]VOLTage:LIMit[:HIGH] Command......................................................................................... B-12
B.53 [SOURce:]VOLTage:LIMit[:HIGH]? Query.................................... ... ...................................................... B-13
B.54 [SOURce:]VOLTage:MODE Command.................................................................................................. B-13
B.55 [SOURce:]VOLTage:MODE? Query...................................................................................................... B-13
B.56 [SOURce:]VOLTage:PROTection[:LEVel] Command............................................... ............................. B-13
B.57 [SOURce:]VOLTage:PROTection[:LEVel]? Query................................................................................. B-13
B.58 [SOURce:]VOLTage[:LEVel]:TRIGgered[:AMPlitude] Command........................................................... B-13
B.59 [SOURce:]VOLTage[:LEVel]:TRIGgered[:AMPlitude]? Query............................................................... B-14
B.60 [SOURce:]FUNCtion:MODE? Query...................................................................................................... B-14
B.61 STATus:OPERation:CONDition? Query................................................................................................. B-14
B.62 STATus:OPERation:ENABle Command................................................................................................ B-15
B.63 STATus:OPERation:ENABle? Query..................................................................................................... B-15
B.64 STATus:OPERation[:EVENt]? Query..................................................................................................... B-15
B.65 STATus:PRESet Command................................................................................................................... B-16
B.66 STATus:QUEStionable[:EVENt]? Query................................................................................................ B-16
B.67 STATus:QUEStionable:CONDition? Query............................................................................................ B-16
B.68 STATus:QUEStionable:ENABle Command............................................................................................ B-16
B.69 STATus:QUEStionable:ENABle? Query .........................................................................................
B.70 SYSTem:BEEP Command..................................................................................................................... B-17
B.71 SYSTem:COMMunication:GPIB:ADDRess
Command..................................................... .................... B-17
B.72 SYSTem:COMMunication:GPIB:ADDRess? Query............................................................................... B-17
B.73 SYSTem:COMMunication:SERial:BAUD Command.............................................................................. B-17
B.74 SYSTem:COMMunication:SERial:BAUD? Query................................................................................... B-17
B.75 SYSTem:COMMunication:SERial:ECHO Command ............................................................................. B-17
B.76 SYSTem:COMMunication:SERial:ECHO? Query.................................................................................. B-17
B.77 SYSTem:COMMunication:SERial:PACE Command.............................................................................. B-17
B.78 SYSTem:COMMunication:SERial:PACE? Query................................................................................... B-18
B.79 SYSTem:COMMunication:SERial:PROMpt CommanD ......................................................................... B-18
B.80 SYSTem:COMMunication:SERial:PROMpt? Query............................................................................... B-18
B.81 SYSTem:ERRor? Query ....................................................................................................................... . B-18
....... B-16
BHK 500-0.4MG SVC 020498 v
TABLE OF CONTENTS
SECTION PAGE
B.82 SYSTem:ERRor:CODE? Query .......................................................................................................... ... B-18
B.83 SYSTem:ERRor:CODE:ALL? Query................................................................................................ ...... B-18
B.84 SYSTem:KLOCk Command................................................................................................................... B-19
B.85 SYSTem:KLOCk? Query........................................................................................................................ B-19
B.86 SYSTem:PASSword:CENable Command.............................................................................................. B-19
B.87 SYSTem:PASSword:CDISable Command............................................................................................. B-19
B.88 SYSTem:PASSword:NEW Command.................................................................................................... B-19
B.89 SYSTem:PASSword:STATe? Query...................................................................................................... B-19
B.90 SYSTem:SECurity:IMMediate Command............................................................................................... B-20
B.91 SYSTem:VERSion? Query..................................................................................................................... B-20
B.92 TRIGger:SOURce Command..................................... .................................................. .......................... B-20
vi BHK 500-0.4MG SVC 032816
LIST OF FIGURES
FIGURE TITLE PAGE
1-1 BHK-MG Series Programmable Power Supply..................................................... ... ..................................... xi
1-2 BHK Series Power Supply, Mechanical Outline Drawing............................................................................ 1-6
1-3 Connector A2J5 Location............................................................................................................................ 1-9
2-1 BHK-MG Series, Front Panel Controls, Indicators and Connectors............................................................ 2-1
2-2 BHK-MG Series, Rear Panel Controls and Connections............................................................................ 2-3
2-3 LCD Power On Defaults.............................................................................................................................. 2-7
2-4 Local Sensing, Slow Mode Selected, Grounding Network Connected,
Floating Output (Factory Default Configuration)....................................................................................... 2-12
2-5 Remote Sensing, Fast Mode Selected, Positive Output Grounded............................................................ 2-12
2-6 Status Port Opto-coupler Active “High” Configuration................................................................................. 2-13
2-7 Status Port Opto-coupler Active “Low” Configuration................................................ ................................. 2-13
3-1 LCD Power On Defaults.............................................................................................................................. 3-5
3-2 Programming Example to Verify Previous Command has Completed........................................................ 3-20
3-3 RS 232 Implementation ........................................ ... .................................................. ................................. 3-22
3-4 Message Structure.................................................................................. ... .. ............................................... 3-27
3-5 Tree Diagram of SCPI Commands Used with BHK-MG Power Supply.................................................... .. 3-28
3-6 Typical Example Of BHK-MG Power Supply Program Using SCPI Commands......................................... 3-31
3-7 Analog Voltage Programming, Simplified Diagram..................................................................................... 3-32
3-8 Analog Current Programming, Simplified Diagram..................................................................................... 3-32
3-9 Analog Programming of Output Voltage (Voltage Mode)
or Voltage Limit (Current Mode) using Resistance.................................................................................. 3-35
3-10 Analog Programming of Output Current (Current Mode)
or Current Limit (Voltage Mode) using Resistance.................................................................................. 3-36
3-11 Analog Programming of Output Voltage (Voltage Mode) or Voltage Limit
(Current Mode) using Isolated (floating) Low Impedance Voltage Source (VS)...................................... 3-38
3-12 Analog Programming of Output Voltage (Voltage Mode) or Voltage
Limit (Current Mode) using Grounded Low Impedance Voltage Source (VS)......................................... 3-39
3-13 Analog Programming of Output Current (Current Mode) or Current Limit
(Voltage Mode) using Isolated (Floating) Low Impedance Voltage Source (VS) .................................... 3-40
3-14 Analog Programming of Output Current (Current Mode) or Current
Limit (Voltage Mode) using Grounded Low Impedance Voltage Source (VS) ........................................ 3-41
3-15 Analog Programming of Output Voltage (Voltage Mode) or Voltage
Limit (Current Mode) using High Impedance, Low Level (1V) Voltage Source (VS)............................... 3-44
3-16 Analog Programming of Output Current (Current Mode) or Current
Limit (Voltage Mode) using High Impedance, Low Level (1V) Voltage Source (VS)............................... 3-45
3-17 Analog Programming of Output Voltage (Voltage Mode) or Voltage
Limit (Current Mode) using Current Source (1mA) (CS)......................................................................... 3-47
3-18 Analog Programming of Output Current (Current Mode) or Current
Limit (Voltage Mode) using Current Source (1mA) (CS)......................................................................... 3-48
3-19 Slow Mode/Fast Mode Operation ............................................................................................................... 3-51
3-20 Series Automatic Configuration .................................................................................................................. 3-55
3-21 Series Master-Slave (Voltage Mode) Configuration.................................................................................... 3-58
3-22 Series Master-Slave (Current Mode) Configuration.................................................................................... 3-59
3-23 Parallel Automatic Configuration............................................... ... ........................................ ....................... 3-63
3-24 Parallel Master-Slave (Voltage Mode) Configuration.................................................................................. 3-65
3-25 Parallel Master-Slave (Current Mode) Configuration .................................................................................. 3-68
4-1 Input VISA Resource Descriptor................................................................................................................. 4-5
4-2 Main Control Panel, Typical........................................................................................................................ 4-6
4-3 Calibration Controls ........................................................................................ ... ......................................... 4-7
4-4 Password Entry....................................... ................................................ ... ................................................. 4-8
4-5 Voltage Calibration...................................................................................................................................... 4-8
4-6 Current Magnifier Window .......................................................................................................................... 4-9
A-1 GPIB Commands............................................................. ... ....................................................................... A-3
B-1 Programming the Output............................................................................................................................ B-3
B-2 Using Display Commands.......................................................................................................................... B-3
B-3 Using LIST Commands and Queries......................................................................................................... B-8
B-4 Programming Current ................................................................................................................................ B-12
BHK 500-0.4MG SVC 032816
vii
LIST OF FIGURES
FIGURE TITLE PAGE
B-5 Programming Voltage................................................................................................................................. B-14
B-6 Using Status Commands and Queries............................................................ ........................................... B-15
B-7 Using System Commands and Queries..................................................................................................... B-19
viii BHK 500-0.4MG SVC 032816
LIST OF TABLES
TABLE TITLE PAGE
1-1 Model Parameters .......................................................................................................................................1-2
1-2 BHK-MG 200W Specifications ............................. ................................................... .. ..................................1-2
1-3 Connector A2J5 Signal Descriptions ..........................................................................................................1-13
1-4 Equipment Supplied ....................................................................................................................................1-13
1-5 Accessories .................................................................................................................................................1-14
1-6 Safety Symbols ...........................................................................................................................................1-14
2-1 Controls, Indicators, and Connectors ..........................................................................................................2-2
2-2 Trigger Port Pin Assignments .....................................................................................................................2-2
2-3 RS232C Port Input/Output Pin Assignments ..............................................................................................2-3
2-4 Status Port Connector Pin Assignments .....................................................................................................2-4
2-5 IEEE 488 Port Connector Pin Assignments ................................................................................................2-4
2-7 Voltage Programming Terminal Strip TB2, Terminal Assignments .............................................................2-5
2-8 Current Programming Terminal Strip TB3, Terminal Assignments .............................................................2-5
2-6 Rear Output Terminal Strip TB1 Terminal Assignments .............................................................................2-5
2-9 Internal Jumper Configuration .....................................................................................................................2-13
3-1 LCD Messages ...........................................................................................................................................3-2
3-2 Key Functions .............................................................................................................................................3-2
3-3 Error Conditions ..........................................................................................................................................3-5
3-4 Memory Location Worksheet ......................................................................................................................3-13
3-5 Sample Program (Model BHK-MG 500-0.4MG) ..........................................................................................3-15
3-6 IEEE 488 (GPIB) Bus Interface Functions ..................................................................................................3-15
3-7 IEEE 488 (GPIB) Bus Command Mode Messages .....................................................................................3-16
3-8 IEEE 488 (GPIB) Bus Data Mode Messages ..............................................................................................3-17
3-9 Rules Governing Shortform Keywords ........................................................................................................3-26
3-10 Feedback Resistor and Current Sensing Resistor Values ..........................................................................3-36
4-1 VISA Resource String Corresponding to Interface .....................................................................................4-5
4-2 Calibration Panel Functions ........................................................................................................................4-7
4-3 Factory Default Calibration Passwords .......................................................................................................4-10
4-4 Calibration Storage .....................................................................................................................................4-12
A-1 IEEE 488.2 Command/query Index ...........................................................................................................A-1
A-2 Standard Event Status Enable Register and Standard Event Status Register Bits ...................................A-1
A-3 Service Request Enable and Status Byte Register Bits .............................................................................A-4
B-1 SCPI Subsystem Command/query Index ..................................................................................................B-1
B-2 Operation Condition Register, Operation Enable Register,
and Operation Event Register Bits ........................................................... .................................. .............B-14
B-3 Questionable Event Register, Questionable Condition Register
and Questionable Condition Enable Register Bits ..................................................................................B-16
B-4 Error Messages ..........................................................................................................................................B-20
BHK 500-0.4MG SVC 020498 ix
SERVICE
WARNING
!
SAFETY INSTRUCTIONS
Read these safety instructions, as well as the applicable installation, operating and servicing instructions
contained in this manual before using the power supply.
Do not touch the output terminals. The high voltage outp ut is dangerous. Electric shock can cause injury or
death.
Do not remove the cover or disassemble the unit. There are n o operator serviceable components or
adjustments inside the unit. High voltage comp onents inside the unit can cause serious injury even with
input power disconnected.
CAUTION
If this power supply is used in OEM equipment, the OEM equipment manufacturer is responsible for
attaching appropriate warning labels on the OEM eq u i pm e nt .
Operating the power supply outside the specified limits for input voltage, temperature, or other environmental conditions noted in this manual can damage the power supply and void the warranty.
Safety Messages
The BHK-MG can be controlled by digital and/or analog inputs. When OUTPUT is set to off from the keypad or the GPIB, an analog input will still produce an output from the BHK-MG which will be indicated on
the LCD. If the output is greater than 8 Volts and the current is higher than 2 LSB’s, a shutdown sequence
begins: the unit will beep, the LCD will flash DIGITAL IS OFF and SET ANALOG OFF, and the unit will shut
down within 25 seconds unless the analog input is turned off. The beeping and controlled shutdown function can be overridden by a jumper option (see Table 2-9.)
There are no operator serviceable p arts inside the case. Service must be referred to authorized personnel.
Using the power supply in a manner not specified by Kepco. Inc. may impair the protection provided by the
power supply. Observe all safety precautions noted throughout this manual. The following table lists symbols used on the power supply or in this manual where applicable.
SAFETY SYMBOLS
SYMBOL Meaning SYMBOL Meaning
WARNING: RISK OF ELECTRIC
SHOCK. WARNING
CAUTION: REFER TO REFERENCED PROCEDURE. CAUTION
INDICATES THE POSSIBILITY
OF BODILY INJURY OR DEATH.
INDICATES THE POSSIBILITY
OF EQUIPMENT DAMAGE.
x 032816
FIGURE 1-1. BHK-MG SERIES PROGRAMMABLE POWER SUPPLY
BHK-MG032816 xi
xii BHK-MG032816
1.1 SCOPE OF MANUAL
WARNING
This manual contains instructions for the installation and operation of the BHK-MG series of
200W output power stabilized voltage or current, d-c power supplies manufactured by KEPCO,
Inc., Flushing, New York, U.S.A.
DANGEROUS AND LETHAL POTENTIALS ARE PRESENT,
BOTH WITHIN THIS POWER SUPPLY, AND AT THE OUTPUT!
Before proceeding to use the power supply, read this manual very carefully. Caution must be used when working with, and making connections
to, this power supply. Use only wires with the proper voltage rating for
high voltage connections. Use the designated plugs for the front panel
output. Be extremely careful when analog programming inputs are used,
especially with the negative output of the power supply grounded.
Unless otherwise specified, always connect the test and measuring
equipment to the input power source using an isolating transformer having a suitable isolating voltage rating. Follow all instructions regarding the
grounding of the test set-up. Refer all servicing to qualified service personnel only.
SECTION 1 - INTRODUCTION
1.2 GENERAL DESCRIPTION
The BHK-MG Power Supply Series (Figure 1-1) are full-range, automatic crossover, linear voltage/current stabilizers with a full rectangular output characteristic. Four single-output models
are available, each of which have two output current ranges as listed in Table1-1.
Although designed as a stand-alone bench top unit, th e full-ra ck cr oss section p ermits mounting
in a standard 19-inch wide rack (see Table1-5). Connections can be made at both rear output
terminals (recommended for rac k mounted configurations) and front output terminals (recommended for bench applications). Sensing output terminals are available at the rear terminals
only. These power supplies operate from either 115V or 230V a-c (nominal - switch selectable),
50 or 60 Hz (nominal) input source power. Since there are no internal adjustments, BHK-MG
Power Supplies offer excellent output voltage/current stability and easy calibration.
Output voltage and current are displayed on an alphanumeric Liquid Crystal Display (LCD).
Control of the BHK-MG can be either local, via the front panel keypad and display, or remote using either analog signals (applied to Analog Programming Terminals), or digital programming
via either the IEEE 488.2 (GPIB) or RS 232 communication bus using SCPI commands. Both
digital control (either local or remote) and analog control can be used simultaneously. Digital
control is done with 12 bits of resolution over the entire voltage/current range.
1.3 SPECIFICATIONS
Ta ble 1-1 lists the parameters applicable to individual models. Table 1-2 lists general specifications applicable to all models except where otherwise noted.
BHK-MG (OPR) 032816 1-1
TABLE 1-1. MODEL PARAMETERS
OUTPUT
MODEL
NUMBER
BHK 300-0.6MG 0 - 300
BHK 500-0.4MG 0 - 500
BHK 1000-0.2MG 0 - 1000
BHK 2000-0.1MG 0 - 2000
VOLTAGE
RANGE
(VOLTS)
OUTPUT
CURRENT
RANGE
(mA)
0 - 600 180
0 - 60 18 33.3 0.008
0 - 400 200
0 - 40 20 83 0.007
0 - 200 200
0 - 20 20 333 0.003
0 - 100 200
0 - 10 20 1333 0.001
MAXIMUM
OUTPUT
POWER
(WATTS)
OUTPUT EQUIVALENT IMPEDANCE (FAST MODE)
VOLTAGE MODE
(SERIES R–L)
R
(Ohms)
d-c
0.025 2.0
0.0625 3.6
0.25 6.0
1.0 35
L (mH)
CURRENT MODE
(PARALLEL R–C)
R
(MOhms)
d-c
3.33 0.013
8.3 0.012
33 0.005
133 0.002
C (F)
TABLE 1-2. BHK-MG 200W SPECIFICATIONS
SPECIFICATION RATING/DESCRIPTION CONDITION
INPUT CHARACTERISTICS
a-c Voltage nominal (switch selectable) 115/230V a-c Single phase
range (switch selectable) 105-125/210-250V a-c
Frequency nominal 50-60Hz
range 47-63Hz
Current 115V a-c 4.0A a-c 200W at output
230V a-c 2.1A a-c
OUTPUT CHARACTERISTICS
NOTE: Current specifications contained in this table refer to source current (delivered by the unit to the load). Sink current (absorbed
by the unit from the load) occurs when the output voltage is programmed to a lower value. The sink current is constant, from
45% to 55% of High Current scale rating; it flows until the output reaches the lower voltage.
Type of Stabilizer Linear with automatic
Adjustment range
(Adjustment is either continuous using analog programming, or stepped using digital
programming)
Digital Programming
resolution
Digital Programming accuracy Voltage 0.025% of rating
Digital Data Readback
accuracy
Source effect Voltage 0.001% E
Load effect Voltage 0.005% E
Voltage and Current 0.025% of rating Current measurement requires calibrated
Voltage 0 to 100% of rating See PAR. 1.4.2.2 and 1.4.2.3 for details
Current 0-100% of rating,
Current 0.05% of rating Both current scales
Voltage 0.05% of rating
Current 0.05% of rating Both current scales, 10-100% of rating
Current 0.002% I
Current 0.015% I
crossover
or 0-10% of rating
0.005% of rating Both current scales, <10% of rating (auto-
max Input voltage
O
max
O
max no load - full load
O
max short - full load
O
Voltage/Current
about analog programming and readback.
Use Menu program to change current
scale (See PAR 3.2.10)
shunt (see PAR. 4.2)
matic 10X magnifier)
105-125/210-250V a-c
1-2 BHK-MG (OPR) 032816
TABLE 1-2. BHK-MG 200W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
OUTPUT CHARACTERISTICS (CONTINUED)
Temperature effect
(per degree C)
Time effect Voltage 0.01% E
Ripple
Voltage: Fast Mode
(rms/p-p)
Fast Mode = internal output
Current: Fast Mode
capacitor not connected.
Slow Mode (default) = internal
output capacitor connected
Voltage 0.01% EO max Ambient temperature
Current 0.02% I
Current 0.02% I
0.002% / 0.02% E
Slow Mode
0.001% / 0.01% E
0.02% / 0.2% I
Slow Mode
0.01% / 0.1% I
max
O
max 0.5-8.5 hours
O
max
O
O
O
max
O
max
O
0 to 50° C
Ambient temperature: 25° C
max
Minus output terminal connected to GND.
max
Current: Short with calibrated shunt.
Voltage: Nominal load
Programming
rise time (R)/fall time (F)
Voltage: Fast Mode
Slow Mode
s (R)/180s (F)
180
90ms (R)/175ms (F)
Load EO max/IO max,
Vout between zero and E
between 10% and 90% of E
Current: Fast Mode
Slow Mode
s (R)/200s (F)
200
90ms (R)/175ms (F)
Load EO max/IO max,
Iout between zero and I
between 10% and 90% of I
Transient recovery to load
change (Amplitude/time constant)
Small signal 3-dB Bandwidth
(Fast Mode)
Voltage Fast Mode
Slow Mode
Current Fast Mode 50% I
Voltage 2.5 KHz Load = E
5% E
max/100 sec
O
0.5% E
max/1 msec
O
max/100 sec Iout = IO max
O
Vout=400 Vdc and load switched between
infinity and 400/IO max
and load switched between
0.1 x E
E
Vprog out = 200V d-c (from keypad)
max/IO max and
O
max/IO max
O
max/IO max,
O
Vv analog in = 0.2 V rms (from analog
input terminal)
Current 2.3 KHz Load = E
max/IO max,
O
Iprog out = 200 x I
keypad)
Vc analog in = 0.2 V rms (from analog
input terminal)
Slew rate (Fast Mode) Voltage >1.2% E
max (V/s) Load EO max/IO max,
O
Measured as the chord of the exponential
response to a square waveform between
Current >1.1% I
zero and E
max (mA/s) Load = calibrated shunt
O
Measured as the chord of the exponential
O
response to a square waveform between
zero and I
O
Overshoot None Turn ON/OFF
Output Impedance See Table 1-1.
Remote Sensing Range
(default = local sensing)
D-C Isolation voltage BHK 300-0.6MG,
BHK 500-0.4MG,
0.5 V d-c per lead Provisions for 4-terminal (Kelvin) connection to load
1KV d-c or p-p plus max.
Between either output terminal and ground
output voltage
BHK 1000-0.2MG
BHK 2000-0.1MG 0.5KV d-c or p-p plus max.
Between either output terminal and ground
output voltage
max, measured
O
max
O
max, measured
O
max
O
max/EO max (from
O
max and back to zero.
max and back to zero.
BHK-MG (OPR) 032816 1-3
TABLE 1-2. BHK-MG 200W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
OUTPUT CHARACTERISTICS (CONTINUED)
Withstand voltage (All models) 1350V a-c/1 min Between shorted inputs and chassis
BHK 300-0.6MG 1950V d-c/1 min Between shorted outputs and chassis.
BHK 500-0.4MG 2250V d-c/1 min
BHK 1000-0.2MG
BHK 2000-0.1MG
Chassis connection to ground
resistance
Leakage Current 25
Enable/Disable Output Power Local Front panel Keypad Enables/disables digital programming sig-
Remote - IEEE 488 (GPIB) port
Output Display Output voltage is displayed with two decimals for BHK 300-0.6MG and
Protection Overtemperature: See PAR. 1.4.10a
Overvoltage/Overcurrent: 0 to 1.1 x EOmax
Uneven voltage/current
in pass element:
Fan failure: See PAR. 1.4.10d
AC line failure: See PAR. 1.4.10e
Interruption between sens-
ing and power terminals:
Overload of main or
auxiliary power transformer:
Internal Output Capacitor
(Default state = internal output
capacitor connected.)
Reference Voltages for analog
programming:
Status port Type Output transistor (open collector) from an optocoupler
Series Connection Automatic or Master-
Parallel Connection Automatic or Master-
BHK 300-0.6MG 20
BHK 500-0.4MG 10
BHK 1000-0.2MG 4
BHK 2000-0.1MG 2
Output Ratings Ic = 8mA d-c, Vceo = 40V d-c, Pd = 150mW@25° C
2800V d-c/1 min
100 mohms max. Between ground input connection and
chassis @ 30A
A rms /100 uA p-p, for 115V a-c input voltage
(chassis to EARTH-GND)
nals only. Shutdown line is for disable only
- RS 232 port
- Trigger port (shutdown
line)
BHK 500-0.4MG and one decimal for BHK 1000-0.2MG and BHK
2000-0.1MG.Output current for all models is displayed with two decimals when current range is set to High, and three decimals when current range is set to Low.
0 to 1.1 x IOmax (except
BHK 300-0.6MG)
0 to 1.08 x IOmax (BHK
300-0.6MG only)
- removing the signal does not reenable
the output (See PAR. 3.2.7.3).
See PAR. 1.4.4
See PAR. 1.4.10c
See PAR. 1.4.10f
See PAR. 1.4.10g
F ±6%
F ±6%
F±10%
All internal output capacitors are
non-polarized type.
F±10%
+10 ±-0.2V d-c
–10 ±-0.2V d-c
Logic Saturated transistor when AC line is present
For slave unit, use analog programming
Slave Operation, limited
by the d-c isolation limit
voltage
Slave Operation
only.
For slave unit, use analog programming
only.
max.10 mA d-c
1-4 BHK-MG (OPR) 032816
TABLE 1-2. BHK-MG 200W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
GENERAL (ENVIRONMENTAL) CHARACTERISTICS
Temperature Operating 0° to +50° C
Storage -20° to +70° C
Humidity
Shock 20g, 11msec ±50%
Vibration 5-10Hz 10mm
Cooling Built-in Fan, exhaust air to rear
0 to 95% RH
half sine
double amplitude
Non condensing
operating & storage
Non operating, 3-axes,
3 shocks each axis
Non operating, 3-axes,
1 hour each axis
PHYSICAL CHARACTERISTICS
Dimensions See Figure 1-2.
Weight English 45 lbs. Unpacked
Metric 20 Kg
a-c source connections Front Circuit Breaker, 2-pole
Rear Detachable IEC 3-wire
type connector
Interlock switch, 1-pole
d-c output terminals Rear panel Terminal Block (11 posi-
tions),
Front panel Jacks (2) ±Output
Control Local: Digital control using front panel keypad(24 pads) and LCD
Remote: Digital control using rear panel IEEE 488 Bus (24 pin female connec-
tor). Analog control using two rear panel terminal strips (10 positions)
for voltage and current
Digital display
front panel
Voltage, current, mode,
settings, menu, program,
etc.
Interlock switch monitors plastic cover
over rear panel terminals.
±Output, ±Sense, Ground, Internal Capacitor (–), Grounding Network
2 x 16 character alphanumeric LCD with
LED backlight
BHK-MG (OPR) 032816 1-5
FIGURE 1-2. BHK SERIES POWER SUPPLY, MECHANICAL OUTLINE DRAWING (SHEET 1 OF 2)
1-6 BHK-MG (OPR) 032816
FIGURE 1-2. BHK SERIES POWER SUPPLY, MECHANICAL OUTLINE DRAWING (SHEET 2 OF 2)
BHK-MG (OPR) 032816 1-7
1.4 FEATURES
1.4.1 LOCAL CONTROL
Front panel keypad entries and an LCD type display are utilized for setting and/or adjusting output voltage and current under local control. The keypad's keys are organized to either directly
execute commands, or to introduce a program that can either be run once or cycled. Calib ration
of the unit is facilitated by a password -protected, menu-driven procedure from the front panel.
Refer to PAR. 3.2 for more information.
1.4.2 REMOTE CONTROL
Remote control of the BHK-MG Power Supply can be accomplished either through digital or
analog programming.
1.4.2.1 DIGITAL PROGRAMMING
Digital control is available directly via either the IEEE 488.2 (GPIB) or RS 232 bus using SCPI
commands. Nearly all features available in local mode can be accessed in remote mode
through digital programming. Refer to PAR’s. 3.3 and 3.5 for more information.
1.4.2.2 ANALOG PROGRAMMING
BHK-MG Power Supplies can also be controlled remotely using analog means, such as analog
voltage or current, fixed or variable resistors, or a combination of them. This great flexibility is
made possible by two uncommitted amplifiers (for voltage and current) and two reference voltages (+10V d-c and -10V d-c) available at the rear panel analog programming terminals. The
chosen means of control (voltage, current, resistance, or a combination) must deliver 0 to –10V
d-c at the output of the uncommitted amplifiers in order to have control over the entire range of
the output voltage/current limit or output current/voltage limit. The analog programming port is
not calibrated, however the zero point is accurate to less than 0.1%. The full scale tolerance is
2% maximum when using the preamplifier with external matched-pair resistors. Refer to PAR.
3.6 for more information about remote programming using the analog programming terminals.
1.4.2.3 ANALOG READBACK
The output voltage and current analog readback signals (un calibrated), as well as some flag signals, are available for testing and customer usage via an internal connector (A2J5). Refer to
Table 1-3 for details about A2J5 signals; refer to Table 1-5 to obtain the A2J5 mating conn ec tor.
See Figure 1-3 for connector A2J5 location. Wires (with isolation rated for at least the nominal
output voltage of the unit) can be routed through the wire entry bushing at the rear panel (see
Figure 2-2).
1.4.3 DIGITAL CALIBRATION
The BHK-MG Power Supply contains no internal adjustments. Calibration is done entire ly via
the front panel keypad and LCD, using a calibrated DVM and a corresponding precision sh unt
resistor. Calibr ation instructions appear on the front panel LCD after a password is entered.
Calibration constants for programmi ng and re ad-back activities are calculated by the microcontroller and stored in the non-volatile memory. No internal adjustments are necessary The previous calibration is saved and can be restored if desired . The origin al factory calibrat ion can also
be restored. Refer to Section 4 for more information.
1-8 BHK-MG (OPR) 032816
FIGURE 1-3. CONNECTOR A2J5 LOCATION
1.4.4 OVERVOLTAGE/OVERCURRENT PROTECTION
Overvoltage and Overcurrent protection values can be individually programmed. The range for
overvoltage and overcurrent values are 0 to 1.1 x E
age/current is maintained at or above the overvoltage/overcurrent protection value for more
than 9ms, the protection circuit latches the pass element off, discharges the output capacitor,
trips the POWER circuit breaker to OFF and sends a flag on a dedicated line (status port connector). The default values are 1.1 x E
max for overvoltage protection, and 1.1 x IOmax for
O
overcurrent protection. Refer to PAR. 3.2.11 for more information.
1.4.5 USER-DEFINED VOLTAGE/CURRENT LIMITS
The BHK-MG Power Supply can be programmed not to exceed user-defined values that can be
lower than the maximum values. For example, th e BHK 500-0 .4MG, which has maximum output
values of 500V d-c, 0.4A d-c, can be limited to 100V d-c, 0.1A d-c for working with circuitry that
might be damaged by higher levels. Once the limit s are set, the power supply becom es, in effect
a 100V d-c, 0.1A d-c supply and values exceeding the limit values will not be accepted. Refer to
PAR. 3.2.12 for more information.
max, 0 to 1.1 x IOmax. If the output volt-
O
BHK-MG (OPR) 032816 1-9
1.4.6 NONVOLATILE STORAGE OF PROGRAMMED SEQUENCES OR ACTIVE SETTINGS
The BHK-MG Power Supply contains 40 memory locations for each current range that can be
used either to preprogra m a s eq u en ce of output values or to store active settings. For programming sequences each memory location accommodates six parameters: output voltage, output
current, overvoltage, overcurrent, time (how long the parameters are in effect) and the next
address in the sequence. Values are stored in the nonvolatile memory, and are retained when
the unit is turned off. Refer to PAR. 3.2.16 for more information.
The same 40 memory locations are also available to save the active pr ogr amm ed settings ( vo ltage, current, overvoltage, overcurrent). The saved setting can be recalled by specifying the
memory location. Refer to PAR’s. 3.2.13 and 3.2.14 for more infor ma tio n .
1.4.7 CURRENT SCALE
Output current of the power supply can be scaled down by a factor of 10, while at the same time
increasing the current resolution by a factor of 10. For example the BHK 500-0.4MG has maximum output values of 500V d-c, 0.4A d-c and a current resolution of 0.1mA d-c; scaling down
the output current results in a power supply with maximum values of 500V d-c, 0.04A d-c with a
current resolution of 0.01mA d-c. C urrent scalin g is easily accomplished using the Menu. Refer
to PAR. 3.2.10 for more information.
Measurement of a decreasing output current of the power supply that falls below 8.98% ±0.01%
of the rated value is automatically measured with increased resolution/accuracy by a factor of
10 until the current rises above 9.69% ±0.01% of rated value.
The factory setting is for the high current range, shown on the top line of the LCD in command
entry status by the message “Ihigh.” The current scale se tting is retained, and displa yed up on
turn-on as either Ihigh or Ilow.
1.4.8 FAST MODE/SLOW MODE SELECTION
BHK-MG Series Power Supplies can be configured by external strapping for either slow mode
operation with the internal output capacitor connected to the output, or fast mode operation with
the internal output capacitor disconnected from the output. The slow mode (default state) is recommended for voltage stabilization because of its low output noise and low recovery amplitude
to a dynamically changing load. The fast mode offers a faster respo nse to st ep or dy nami c programming of the output voltage (in voltage mode), when the power supply is used as a power
amplifier. Fast mode is also recommended for current stabilization because of its fast response
to a dynamically changing load. Refer to PAR. 3.7.1 for more information.
1.4.9 EXTERNAL TRIGGER PORT
The external trigger port provides two functions: a trigger input can be used to resto re the output
to previously defined settings using SCPI commands (see PAR. 3.3.4) and a shutdown input
can be used to immediately shut down the power supply output (see PAR. 3.2.7.3).
1-10 BHK-MG (OPR) 032816
1.4.10 BUILT-IN PROTECTION
BHK-MG Series Power Supplies provide built-in protection against the following:
a. Overtemperature of the pass element. Heatsink temperature is monitored. If an overtem-
perature condition is maintained for more than 0.5ms, the following actions ar e initiated: th e
pass element is cut off and latched off, the output capacitor is discharged, the LCD displays
the error message “BHK FAILURE“ and an error message is sent on the IEEE 488 Bus.
b. Overvoltage/overcurrent at the output. See PAR. 1.4.4
c. Uneven voltage/current in the pass element. Voltage is monitored across dif ferent tra nsis-
tors of the pass element while current is monitored through the different branches. If uneven
voltage/current continues for more than 11ms, the pass element is latched off, the output
capacitor is discharged, the POWER circuit breaker is tripped to OFF and a flag is sent to the
host computer on a dedicated line (Status Port connector)
d. Fan failure. If fan current drops below predetermined value continuously for more than
16ms, the pass element is latched off, the output capacitor is discharged, the LCD displays
the error message “BHK FAILURE” and an error message is sent on IEEE 488 Bus.
e. AC line failure. If AC line is missing for more than 8 ms, a flag is sent to the host computer
on a dedicated line (Status Port connector). In addition, if the jumper at A7-J12 is installed
(default state), the pass element is latched off, the output capacitor is discharged, and th e
POWER circuit breaker is tripped to OFF.
f. Interruption between the sensing and corresponding power output terminals. If there
is an interruption between the sensing and power terminals, two diodes connected in parallel
between the sensing lead and the corresponding power lead (one forward biased and one
reverse biased), allow the power supply to continue to function.
g. Overload of the main or auxiliary power transformer. If input current of the main trans-
former exceeds 7A a-c @ 115V a-c or 3.5A a-c @ 230V a-c, the input POWER circuit
breaker is tripped to OFF, the pass element is latched off, the output capacitor is discharged,
and a flag is sent to the Status Port connector. The reaction time is inversely proportional to
the input overcurrent: from a minimum of 10ms for 10 times nominal overcurrent, to a maxi-
mum of 100 seconds for 25% above nominal current .
If input current of the auxiliary power transformer exceeds a predetermined value, in most
cases the input POWER circuit breaker is tripped to OFF (if jumper A7J12 is installed), the
pass element is latched off, the output capacitor is discharged, and a flag is sent to the Sta-
tus Port connector . If the ca use of the overload is a problem in the protection circuit, the input
POWER circuit breaker may not trip off: the pass element will be latched off and the output
capacitor will discharge more slowly, and a flag is sent to the status port. The reaction time in
this case is determined by PTC (positive temperature coefficient) thermistor A5R1 between
30 and 100 seconds.
h. Current Limit. The current through the main branch of the pass element is monitored. If this
current is maintained between 1.8 to 2.2 time s larger than the nominal value f or more than
11ms, the pass element is latched off, the output capacitor is discharged, and the POWER
circuit breaker is tripped to OFF.
BHK-MG (OPR) 032816 1-11
1.4.11 CURRENT SINK CAPABILITY
BHK-MG 200W Series power supplies are able to sink up to 5% of the nominal current when in
voltage mode and 50% of the unit's maximum rated current when in current mode. The fixed
current mode sink value is model dependent and has a tolerance of 10%. Since negative current is not displayed on the fr ont panel meter, it is transparent to the user when the unit enters
sink mode.
This capability is useful in applications such as capacitor testing, where the sink capability
allows the rapid discharge of the device under test, permitting subsequent tests to be started
earlier, thus increasing the throughput of the testing process.
The sink current in current mode is quite stable, allowing this feature to be used with the discharging process to determine the value of a capacitor under test by measuring the discharge
time, using the formula C = T x I / V (the charge time, which is more accurate, can also be used
in the formula), where
T = discharge or charge time
V = change in voltage from fully charged to fully discharged, or vice versa.
I = discharging or charging current (BHK-MG charging current has a tolerance of
0.05% of nominal value, discharge current has a tolerance of 10% of nominal value)
The value of the capacitor under test can be calc ula ted d ire ctly by m easur ing T and either using
the above formula and the appropriate tolerance for I, or by comparing T to that of a known
capacitor value.
Once the capacitor under test completely discharges, current from the power supply’s internal
current generator will flow through the output protection diode (or, in some models, multiple
diodes), resulting in a slight reverse voltage at the output which will be clamped to the value of
the voltage drop across the diode(s).
1.4.12 ANALOG READBACK AND FLAG SIGNALS AVAILABLE FOR CUSTOMER USE
Some internal signals produced by the unit are available at conn ector A2 J5 for either monito ring
or testing purposes. Refer to Table 1-3 for a description of available signals
1-12 BHK-MG (OPR) 032816
TABLE 1-3. CONNECTOR A2J5 SIGNAL DESCRIPTIONS
SIGNAL PIN. NO. VALUE TYPE
Current Scale Flag 1
Step Down Flag 2
Power GND 3 N/A
V-C Mode Flag 4
Signal GND 5, 7 N/A
Current Monitor
(not calibrated)
Voltage Monitor
(not calibrated)
* Recommended load equal to or greater than 10K ohms.
6
8
0V for HIGH current scale
> +13V for LOW current scale
< -11V for steady or step-up output
> +11V for step-down output, or when protection circuit has functioned and “BHK
FAILURE” error message is displayed
< -11V for CV (Constant Voltage) mode
> +11V for CC (Constant Current) mode
0V ± 10mV (for IO = 0mA) to
+10V ± 0.12V (for IO = Full Scale)
0V ± 10mV (for EO = 0V to)
+10V ± 0.25V (for EO = Full Scale)
1.5 EQUIPMENT SUPPLIED
Equipment supplied with the unit is listed in Table 1-4.
Collector of PNP transistor (A2Q3)
through 1K resistance.*
Output of open loop Op Amp
(A2U4B) through 1K resistance.*
Recommended to be used as Return
for signals at pins 1, 2, and 4.*
Output of open loop Op Amp
(A2U4A) through 1K resistance.*
Recommended to be used as Return
for signals at pins 6 and 8.*
Output of closed loop Op Amp
(A2U7) *
Output of closed loop Op Amp
(A2U1) *
TABLE 1-4. EQUIPMENT SUPPLIED
ITEM
Power Cord 118-0557 1
Plug, 2-contact for ± front panel output jacks 142-0489 1
Contact, pin type (used on plug 142-0489) 107-0361 2
Status Port mating connector 143-0296 1
Two-terminal Link for rear panel output 172-0300 2
Three-terminal Link for rear panel output 172-0305 2
Four-terminal Link for rear panel output (installed) 172-0407 2
Five-terminal Link for rear panel output 172-0321 1
Six-terminal Link for rear panel output 172-0408 1
PART NUMBER QUANTITY
BHK-MG (OPR) 032816 1-13
1.6 ACCESSORIES
!
Accessories for the BHK Power Supply are listed in Table 1-5.
TABLE 1-5. ACCESSORIES
ITEM FUNCTION
IEEE 488 (GPIB) Cable, 1m long Connect BHK-MG Power Supply to GPIB bus. SNC 488-1
IEEE 488 (GPIB) Cable, 2m long Connect BHK-MG Power Supply to GPIB bus. SNC 488-2
IEEE 488 (GPIB) Cable, 4m long Connect BHK-MG Power Supply to GPIB bus. SNC 488-4
Slide (2) Allows rack-mounted units to slide in and out. CS-01, -02, -03 (Kepco)
External Trigger Port mating connector Allows access to external trigger function. 142-0527 (Kepco)
RS 232 Port Adapter Cable Kit Contains RJ 45 Patch cord, two RS 232 adapt-
ers (one with male pins to connect to DTE
equipment and one with female pins to connect
to a personal computer), and an RS 232 Loop
Back test Connector (to test RS 232 communication and aid in isolating RS 232 communication problems).
Mating connector for A2J5 (Analog Readback and Flags)
Allow user access to analog readback and flag
signal; see Table 1-3 for details.
PART NUMBER
110-QD-14-2 (Jonathan)
SP-2501 (CUI)
KIT 219-0436
143-0359
1.7 SAFETY
There are no operator serviceable parts inside the case. Service must be referred to authorized
personnel. Using the power supply in a manner not specified by Kepco. Inc. may impair the protection provided by the power supply. Observe all safety precautions noted throughout this manual. Table 1-6 lists symbols used on the power supply or in this manual where applicable.
TABLE 1-6. SAFETY SYMBOLS
SYMBOL MEANING
CAUTION: RISK OF ELECTRIC SHOCK.
CAUTION: REFER TO REFERENCED PROCEDURE.
WARNING INDICATES THE POSSIBILITY OF BODILY INJURY OR DEATH.
CAUTION INDICATES THE POSSIBILITY OF EQUIPMENT DAMAGE.
1-14 BHK-MG (OPR) 032816
SECTION 2 - INSTALLATION
2.1 UNPACKING AND INSPECTION
This instrument has been thoroughly inspected and tested prior to packing and is ready for
operation. After careful unpacking, inspect for shipping damage before attempting to operate.
Perform the preliminary operational check as outlined in PAR 2.5. If any indication of damage is
found, file an immediate claim with the responsible transport service.
2.2 TERMINATIONS AND CONTROLS
a). Front Panel: Refer to Figure 2-1 and Table 2-1.
b). Rear Panel: Refer to Figure 2-2 and Table 2-1.
FIGURE 2-1. BHK-MG SERIES, FRONT PANEL CONTROLS, INDICATORS AND CONNECTORS
BHK-MG (OPR) 032816 2-1
TABLE 2-1. CONTROLS, INDICATORS, AND CONNECTORS
CONTROL, INDICATOR,
CONNECTOR
FRONT PANEL
A-C line indicator Lights to indicate unit turned on and a-c power applied.
FUNCTION
LCD 2 x 16 character Liquid Display with LED backlight. Shows voltage, current
Keypad 24 keys used for local operation of the power supply; Refer to Table 3-2 for
POWER circuit breaker Circuit breaker used to turn unit on and off.
(+) and (–) output jacks Provide front panel access to d-c output of power supply.
IEEE 488 PORT 24-pin GPIB connector used to connect to GPIB bus (see Table 2-5 for pin
RS 232 PORT 8-pin telephone jack type connector used to connect to RS 232 bus (see T able
STATUS PORT Notifies host computer either that a-c input is not present or a major failure of
EXTERNAL TRIGGER PORT 4-pin connector used to restore unit to pre-established setting or to shut down
OUTPUT TERMINALS barrier strip TB1 Provides Power Supply output connection points. (See Table 2-6 for terminal
V PROG terminal strip TB2 Provides input/output signals for analog programming of output voltage or
I PROG terminal strip TB3 Provides input/output signals for analog programming of output current or cur-
mode, settings, menu, program, etc.
details.
REAR PANEL
assignments).
2-3 for pin assignments).
power supply has occurred.(see Table 2-4 for pin assignments).
the output. (see Table 2-2 for pin assignments). NOTE: Mating connector is a
3-pin plug.
assignments)
voltage limit. (See Table 2-7 for terminal assignments.)
rent limit. (See Table 2-8 for terminal assignments.)
AC SELECTOR switch Used to select between nominal input line voltage of 115 V a-c or 230 V a-c.
AC INPUT connector Provides a-c source power to unit.
Interlock switch Provides protection when terminal strip cover is removed by interrupting a-c
power to the unit.
TABLE 2-2. TRIGGER PORT PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
1 Trigger- Shutdown RTN Return for TRIGGER and SHUTDOWN signals.
TRIGGER PORT
(connector A1J2)
2
4
SHUTDOWN Logic 0 causes BHK output to go be disabled (see
PAR. 3.2.7.3).
TRIGGER Logic 0 triggers BHK to previously stored setting (see
PARs. 3.3.4 and B.92.)
2-2 BHK-MG (OPR) 032816
TABLE 2-3. RS232C PORT INPUT/OUTPUT PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
1 RTN Return 1 Signal Ground
2 Not Used Not Used 2 Receive Data
3 TXD Transmit Data 3 Transmit Data
RXD Receive Data
4
RS 232
PORT
(connector A1J5)
5 RTN Return 5 Signal Ground
Not Used Not Used
6
RTN Return
7
8 RTN Return 8 Clear To Send (protocol not used)
Adapter Cable (P/N KIT 219-0436)
PIN FUNCTION
Data Terminal Ready (protocol not
4
used)
Data Set Ready (protocol not
6
used)
Request To Send (protocol not
7
used)
9 Signal Ground
FIGURE 2-2. BHK-MG SERIES, REAR PANEL CONTROLS AND CONNECTIONS
BHK-MG (OPR) 032816 2-3
TABLE 2-4. STATUS PORT CONNECTOR PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
1 Not Used.
2 Not Used.
3 Not Used.
Emitter Emitter of LED-transistor optocoupler. Notifies host com-
puter of absence of a-c input or a major power supply failure, active “low” (see PAR 1.4.10), requires pin 7 to be
connected to the “+“ of the host computer d-c supply as
described in PAR. 2.9.
puter of absence of a-c input or a major power supply failure, active “high” (see PAR 1.4.10), requires pin 4 to be
connected to the “–“ of the host computer d-c supply as
described in PAR.2.9.
STATUS PORT
CONNECTOR A5J4
4
5 Not Used.
6 Not Used.
Collector Collector of LED-transistor optocoupler. Notifies host com-
7
8 Not Used.
9 Not Used.
TABLE 2-5. IEEE 488 PORT CONNECTOR PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
IEEE 488
PORT
A1J1
1D
2D
3D
4D
5 EOI End or Identify
6 DAV Data Valid
7 NRFD Not Ready for Data
8 NDAC Not Data Accepted
9 IFC Interface Clear
10 SRQ Service Request
11 ATN Attention
12 SHIELD Shield
13 D
14 D
15 D
16 D
17 REN Remote Enable
18 GND Ground (signal common)
19 GND Ground (signal common)
20 GND Ground (signal common)
21 GND Ground (signal common)
22 GND Ground (signal common)
23 GND Ground (signal common)
24 LOGIC GND Logic Ground
I01 I/O Line
I02 I/O Line
I03 I/O Line
I04 I/O Line
I05 I/O Line
I06 I/O Line
I07 I/O Line
I08 I/O Line
2-4 BHK-MG (OPR) 032816
TABLE 2-6. REAR OUTPUT TERMINAL STRIP TB1 TERMINAL ASSIGNMENTS
TERMINAL SIGNAL NAME FUNCTION
1 +S Positive sense connection
2 + OUT Positive d-c output connection
3 GND NET Grounding network connection
4 GND Ground (chassis) connection
5 – OUT Negative d-c output connection
6 –S Negative sense connection
7 – OUT C Connection to internal output capacitor
TABLE 2-7. VOLTAGE PROGRAMMING TERMINAL STRIP TB2, TERMINAL ASSIGNMENTS
TERMINAL SIGNAL NAME FUN CTION
1 –10V –10V d-c reference voltage
2 V(NINV) Noninverting input of uncommitted amplifier
3 SGND Signal common
4 V(+IN) Programming input for positive input signal
5 +10V +10V d-c reference voltage
6 V(INV) Inverting input of uncommitted amplifier
7 V(FBK) Internal feedback resistor; the other end is connected to
uncommitted amplifier output
8 V(OUT) Output of uncommitted amplifier
9 –V EXT External analog programming voltage input: 0 to –10V pro-
10 SGND Signal common
grams 0 to 100% of EOmax.
TABLE 2-8. CURRENT PROGRAMMING TERMINAL STRIP TB3, TERMINAL ASSIGNMENTS
TERMINAL SIGNAL NAME FUN CTION
1 –10V –10V d-c reference voltage
2 C(NINV) Noninverting input of uncommitted amplifier
3 SGND Signal common
4 C(+IN) Programming input for positive input signal
5 +10V +10V d-c reference voltage
6 C(INV) Inverting input of uncommitted amplifier
7 C(FBK) Internal feedback resistor; the other end is connected to
uncommitted amplifier output
8 C(OUT) Output of uncommitted amplifier
9 C EXT External analog programming voltage input: 0 to –10V pro-
10 SGND Signal common
grams 0 to 100% of IOmax. Usually connected to output of
uncommitted amplifier.
BHK-MG (OPR) 032816 2-5
2.3 SOURCE POWER REQU IREMEN TS
WARNING
WARNING
BEFORE APPLYING AC SOURCE POWER TO THE POWER SUPPLY, VERIFY THAT THE
LINE VOLTAGE TO BE SUPPLIED MATCHES THE POSITION OF THE AC INPUT SELECTOR SWITCH AT THE REAR PANEL (FACTORY DEFAULT IS 115V).
This power supply operates with the installed circuit breaker from single phase AC mains power
over the specified voltage and frequency ranges without adjustment or modification. The AC
INPUT SELECTOR switch located on the rear panel (Figure 2-2) allows selection of either
115Vac or 230Vac source power.
The nominal AC current absorbed by the BHK-MG Power Supply from the power source is 3.7A
a-c @115V a-c and 1.9A a-c @230V a-c; the power source must be able to deliver the nominal
current as well as surge current ten times larger than nominal.
2.4 COOLING
The power devices used within the power supply are maintained within their operating temperature range by means of internal heat sink assemblies cooled by an internal (d-c type) cooling
fan.
ALL INLET AND EXHAUST OPENINGS AROUND THE POWER SUPPLY CASE MUST BE
KEPT CLEAR OF OBSTRUCTION TO ENSURE PROPER AIR ENTRY AND EXHAUST.
Periodic cleaning of the power supply interior is recommended. If the power supply is rack
mounted, or installed within a conf ined sp ac e, care must be t aken that th e ambient tem perature,
which is the temperature of the air immediately surrounding the power supply, does not rise
above the specified limits (see Table 1-2).
2.5 PRELIMINARY OPE RATIONAL CHECK
BEFORE APPLYING AC SOURCE POWER TO THE POWER SUPPLY, VERIFY THAT THE
LINE VOLTAGE TO BE SUPPLIED MATCHES THE POSITION OF THE AC INPUT SELECTOR SWITCH AT THE REAR PANEL (FACTORY DEFAULT IS 115V).
A simple operational check after unpacking and before equipment installation is advisable to
ascertain whether the power supply has suffered damage resulting from shipping.
Refer to Figures 2-1 and 2-2 for location of operating controls and electrical connections. Tables
2-1 and 3-2 explain the functions of operating controls/indicators and keypad keys, respectively.
1. With POWER switch set to down (OFF) position, connect the power supply to source
power.
2. With no load connected, set POWER switch to the up (ON) position. Each time the unit is
turned on an internal self-test is performed and the power on indications (Figure 2-3) are
visible. If these indications do not appear, the power supply will be inoperative.
2-6 BHK-MG (OPR) 032816
The alphanumeric display (LCD) indicates the model and GPIB address. After a few sec-
Loc CV
0.000A0.000V (:_:_:)
NOTE: (:_:_:) indicates blinking colon (:), Command Entry status
(=_=_=) indicates blinking equal sign (=), Data Entry status
Ihigh
onds, the display presents the power supply default valu es: Local mode (LOC), Current Scale
High (Ihigh), Constant Voltage (CV) mode, 0.0V, 0.0A and command entry status (see Figure 2-3.). Overvoltage and overcurrent protection are set to the maximum values (PAR.
1.4.4), but are not displayed. When shipped from the factory, the digital control is set to off.
To enable the output of the BHK-MG, press the OUTPUT ON/OFF key on the front panel
FIGURE 2-3. LCD POWER ON DEFAULTS
NOTE: Six keys with dual functions are labeled with both a command and a num ber. The com-
mand is referred to when the unit is in (:_:_:) command entry status; the number is
referred to when the unit is in (=_=_=) data entry status.
3. Allow unit to warm up for at least 15 minutes.
4. Connect a digital voltmeter (DVM) to the (+) and (-) jacks at the front panel.
5. Press VSET key. Verify bottom line of LCD reads Vset (=_=_=) 0.0 V. Use number
keys to enter nominal output voltage (e .g. for BHK 500-0.4M G, 500V is the nomina l output
voltage) and press ENTER. Output voltage will be displayed at bottom left of LCD. Verify
the LCD reads CV (constant voltage mode).
NOTE: If tolerances specified in the following steps are exceeded, refer to Section 4 and reca-
librate the unit.
6. Compare the programmed output voltage value with the voltage reading of the DVM; the
difference between the two should not exceed 0.025% of the nominal voltage of the unit.
7. Compare the voltage reading of the LC D with that of the DVM; the difference between the
two should not exceed 0.05% of the nominal voltage of the unit.
8. Press VSET key and enter different value for output voltage, then repeat steps 6 and 7
using different values for programmed voltage.
9. Disable the output by pressing OUTPUT ON/OFF key; verify LCD reads 0.0V and 0.0mA.
10. Disconnect DVM and connect precision shunt (see PAR. 4.2) across front panel output terminals; connect DVM across shunt (sensing terminals).
11. Using VSET key, set output voltage to 30V.
12. Similarly, using ISET key, pr ogram output current to the nominal o utput current of the power
supply (e.g., for BHK 500-0.4MG, 400mA is the nominal output current).
BHK-MG (OPR) 032816 2-7
13. Press OUTPUT ON/OFF key to enable the output of the unit. Verify the LCD reads CC
(constant current mode) and a small value for output voltage (RS x I
where R
= resistance of shunt in ohms and I
S
= the actual value for current pro-
o (prog)
x 0.001) in volts,
o (prog)
grammed in step 12 in milliamperes.
14. Note DVM reading (V
1000/R
in milliamperes (mA).
S
15. Compare the programmed output current value (step 12) with the value shown indirectly by
DVM (calculated in step 14); the difference between the two should not exceed 0.05%
I
max ±(TOLRs)% IO, where IO is the output current and TOLRs is the tolerance of the pre-
O
cision shunt (step 10).
16. Compare the output current value shown by the LCD (step 13) with the value shown indirectly by DVM (calculated in step 14); the difference between the two should not exceed
0.05% I
max ±(TOLRs)% IO.
O
17. Repeat steps 15 and 16 using different values for programmed current.
18. Disable the output by pressing OUTPUT ON/OFF key, turn-off power supply and discon-
nect the shunt.
2.6 INSTALLATION
2.6.1 BENCH TOP USE
The unit is designed to be used as a bench top instrument. Front panel output termina ls are provided for easy access. However, if the application requires remote sensing, it is necessary to
use rear output terminals for sensing con n ec tio ns.
) and calculate the output current using the formula IO =V
DVM
DVM
x
2.6.2 RACK MOUNTING
The unit can be mounted directly in a 19-inch wide rack, after the bench-type feet are removed.
Optional slides (see Table 1-5) can be used. Installation of slides can improve access to the unit
(see Figure 1-2).
2.7 WIRING INSTRU CTIO NS
Interconnections between an a-c power source and the power supply, and between the power
supply and its load are as critical as the interface between other types of electronic equipment.
If optimum performance is expected, certain rules for the interconnection of source, power supply and load must be observed by the user. These rules are described in detail in the following
paragraphs.
2.7.1 SAFETY GROUNDING
Local, national and international safety rules dictate the grounding of the metal cover and case
of any instrument connected to the a-c power source, when such grounding is an intrinsic par t of
the safety aspect of the instrument. The ground terminal of the source power connector (Figure
2-2) is connected to the BHK-MG chassis and the instructions below suggest wiring methods
which comply with these safety requirements; however, in the event that the specific installation
for the power system is different from the reco mmended wiring, it is the customer 's responsibility
to ensure that all applicable electric codes for safety grounding requirements are met.
2-8 BHK-MG (OPR) 032816
2.7.2 SOURCE POWER CONNECTIONS
Source power is connected to the power supply via the three-wire input power cable supplied.
2.7.3 D-C OUTPUT GROUNDING
Connections between the power supply and the load and sensing connections may, despite precautions such as shielding, twisting of wire pairs, etc., be influenced by radiated noise, or “pickup”. To minimize the effects of this radiated noise the user should consider grounding one side
of the power supply/load circuit. The success of d-c grounding requires careful analysis of each
specific application, however, and this recommendation can only serve as a general guideline.
One of the most important considerations in establishing a successful grounding scheme is to
avoid GROUND LOOPS. Ground loops are created when two or more points are grounded at
different physical locations along the output circuit. Due to the interconnection impedance
between the separated grounding points, a difference voltage and resultant current flow is
superimposed on the load. The effect of this ground loop can be anything from an undesirable
increase in output noise to disruption of power supply and/or load operation. The only way to
avoid ground loops is to ensure that the entire output/load circuit is fully isolated from ground,
and only then establish a single point along the output/load circuit as the single-wire ground
point.
The exact location of the “best” d-c ground point is entirely dependent upon the spe cific application, and its selection requires a combination of analysis, good judgement and some amount of
empirical testing. If there is a choice in selecting either the positive or negative output of the
power supply for the d-c grou nd point, both sides shou ld be tried, and preferen ce given to the
ground point producing the least noise. Fo r single, isolated loads the d-c ground point is often
best located directly at one of the output terminals of the power supply; whe n remote error sensing is employed, d-c ground may be established at the point of sense lead attachment. In the
specific case of an internally-grounded load, the d-c ground point is automatically e stablished at
the load.
The output terminals (located on both the front or rear panel) for BHK-MG Power Supplies are
d-c isolated (“floating”) from the chassis in order to permit the user maximum flexibility in selecting the best single point ground location. Output ripple specifications as measured at the output
are equally valid for either side grounded. Care must be taken in measuring th e ripple and no ise
at the power supply: measuring devices which are a-c line operated can often introduce additional ripple and noise into the circuit.
There is, unfortunately, no “best” method for interconnecting the load and power supply. Individual applications, location and nature of the load require careful analysis in each case. Grounding a single point in the output circuit can be of great importance. It is hoped that the preceding
paragraphs will be of some assistance in most cases. For help in special applications or difficult
problems, consult directly with Kepco's Application Engineering Department.
2.7.4 POWER SUPPLY/LOAD INTERFACE
The general function of a voltage or current stabilized power supply is to deliver the rated output
quantities to the connected load. The load may have any conceivable characteristic: it may be
fixed or variable, it may have predominantly resistive, capacitive or inductive parameters; it may
be located very close to the power supply output terminals or it may be a considerable distance
away. The perfect interface between a power supply and its load would mean that the specified
performance at the output terminals would be transferred without impairment to any load,
regardless of electrical characteristics or proximity to each other.
BHK-MG (OPR) 032816 2-9
The stabilized d-c power supply is definitely not an ideal voltage or current source, and practical
interfaces definitely fall short of the ideal. All voltage-stabilized power supplies have a finite
source impedance which increases with frequency, and all current-stabilized power supplies
have a finite shunt impedance which decreases with frequency. The method of interface
between the power supply outp ut and the load must, therefore, take into acc ount not only the
size with regard to minimum voltage drop, but the configuration with regard to minimizing the
impedance introduced by practical interconnection techniques (wire, bus bars, etc.). The series
inductance of the load wire must be as small as possible as compared to the source inductance
of the power supply: although the error sensing connection to the load compensates for the d-c
voltage drop in the power leads, it canno t compensate for the undesirable output effects of the
power lead inductance. These lead impedances (both power and sensing leads) are especially
important if the load is a) constantly modulated or step-programmed, b) has primarily reactive
characteristics, or c) where the dynamic output response of the power supply is critical to load
performance.
2.7.4.1 CABLE RECOMMENDATIONS
For power cables (positive and negative) No. 20 or 22 AWG stranded wire is recommended for
each (these sizes fit the plugs supplie d for the front panel output connections). The wire insulation must be rated for nominal voltage of the power supply (e.g ., 500V for BHK 500-0.4MG). If a
float voltage is used, the wire insulation must be rated for the nominal voltage of the power supply plus the float voltage; the DC Isolation Voltage (see Table 1-2, under Output Characteristics)
defines the maximum float voltage allowed. For noisy environments, tied pair (adjacent wires
secured with cable ties) or twisted pair cables are recommended. It is recommended that cable
length not exceed 50 feet; for longer cable lengths, contact Kepco.
Remote sensing is used to accurately control voltage at the load rather than at the output terminals of the power supply (local sensing) by compensating for voltage drop (0.5 V d-c per lead) in
the power cables. For sense cables (positive and negative) No. 22 AWG stranded wire is recommended for each. For noisy environments, tied p a ir or twiste d pair cables are recommended.
It is recommended that cable length not exceed 50 feet; for longer cable lengths, contact Kepco.
2.7.5 LOAD CONNECTION - GENERAL
Load connections to the BHK-MG power supply are achieved via the rear output terminal strip
(TB1); (+) and (-) outputs are also available at jacks located on the front panel. Configuration of
the rear output terminal strip is facilitated by five types of links supplied with the unit:
• 2-terminal link: (qty 2)
• 3-terminal link: (qty 2)
• 4-terminal link: (qty 2)
• 5-terminal link: (qty 1)
• 6-terminal link: (qty 1)
These links are used to configure the power supply for local or remote sensing, slow or fast
mode, insertion of the grounding network, isolated (floating) output, and negative or positive
grounded output. The links allow many possible configurations using various combinations of
the configurable parameters noted above.
The BHK-MG power supply is shipped from the factory configured as follows (factory default
configuration): local sensing, grounding network connected, slow mode, output isolated from
2-10 BHK-MG (OPR) 032816
ground (floating). This configuration is obtained using two 4-terminal links connected as shown
in Figure 2-4.
NOTE: REGARDLESS OF OUTPUT CONFIGURATION, OUTPUT SENSE LINES MUST BE
CONNECTED FOR PROPER OPERATION, EITHER LOCALLY, OR AT THE LOAD
(REMOTE). OBSERVE POLARITIES: THE +S TERMINAL (TB1-1) MUST BE CONNECTED TO EITHER +OUT (TB1-2) (LOCAL) OR +LOAD (REMOTE), AND THE - S
TERMINAL (TB1-6) MUST BE CONNECTED TO EITHER –OUT (TB1-5) (LOCAL) OR
–LOAD (REMOTE).
Figures 2-4 and 2-5 are typical load connection diagrams illustrating the configurations
explained in the following paragraphs.
2.7.5.1 LOCAL SENSING/REMOTE SENSING SELECT
Local sensing (factory default configuration) is established by connecting terminals TB1-1
(+S) to TB1-2 (+OUT) and TB1-5 (–OUT) to TB1-6 (– S) (see Figure 2-4). The power supply is
shipped with these connections installed for local sensing.
Remote sensing is established by removing the links between TB1-1, TB1-2 and TB1-6, TB1-7.
The +S and –S lines must be connected at the load (see Figure 2-5).
2.7.5.2 FAST MODE/SLOW MODE SELECT
Fast mode is established when there is no connection between TB1-6 (–S) and TB1-7 (–OUT C)
(see Figure 2-5). Slow mode (factory default configuration) can be established by connecting
TB1-6 to TB1-7, thus connecting the internal output capacitor to the output (see Figure 2-4).
2.7.5.3 GROUNDING NETWORK CONFIGURATION
When the output is floating there is a tendency for large changes in output voltage to affect the
digital programming section, possibly resulting in an erroneous output. The parallel RC grounding network is designed to be connected to ground at the output when the output is floating to
ensure that the digital programming section is not adversely affected by the dynamic swing of
the output. The power supply is shipped with the grounding network connected: a connection
between terminals TB1-3 (GND NET) and TB1-2 (+OUT). To disconnect the grounding network
from the output, remove the connection across TB1-3 and TB1-2 (see Figure 2-4).
2.7.5.4 POSITIVE OUTPUT, NEGATIVE TERMINAL GROUNDED
To configure the BHK-MG as a positive output power supply (referenced to ground), connect the
negative output terminal to ground: connect TB1-4 (GND - CHASSIS) to TB1-5 (–OUT). To
avoid degraded load regulation in current mode it is necessary to remove the grounding network
from the circuit by removing the link between TB1-2 (+OUT) and TB1-3 (GND NET).
BHK-MG (OPR) 032816 2-11
FIGURE 2-4. LOCAL SENSING, SLOW MODE SELECTED, GROUNDING NETWORK CONNECTED,
FLOATING OUTPUT (FACTORY DEFAULT CONFIGURATION)
2.7.5.5 NEGATIVE OUTPUT, POSITIVE TERMINAL GROUNDED
To configure the BHK-MG as a negative output power supply (referenced to ground), connect
the positive output terminal to ground: use a 5-terminal link to connect TB1-4 (GND - CHASSIS)
to TB1-2 (+OUT). Note that when the positive output is grounded, the groun d network (TB1 -3) is
inoperative (see Figure 2-5).
FIGURE 2-5. REMOTE SENSING, FAST MODE SELECTED, POSITIVE OUTPUT GROUNDED
2-12 BHK-MG (OPR) 032816
2.8 OPERATING CONFIGURATION
The complete operating configuration is defined by jumper configuration of internal boards.
Table 2-9 lists the location of the internal jumpers and their function. This information is provided
for reference purposes only, to indicate the configuration options available. Do not attempt to
alter the jumper configuration. For assistance in changing any jumper-selected parameter contact Kepco Applications Engineering.
TABLE 2-9. INTERNAL JUMPER CONFIGURATION
LOCATION JUMPER
DEFAULT
STATUS
FUNCTION
A1
J6 Not Installed May be installed temporarily to force the unit to enter First Time Calibration during
J12 Installed Enables input circuit breaker to trip when input power loss detected.
J13 Installed Enables protection circuit to cut off pass element and to send a flag to digital con-
A7
J14 Installed Enables “share circuit” to act on protection circuit. The share circuit detects uneven
2.9 STATUS PORT
The status port opto-coupler can be configured for either active “high” (see Figure 2-6) or active
“low” (see Figure 2-7).
power-up sequence. This requires the operator to enter the model and perform a
full calibration of the unit.
trol.
voltage or current across the pass element.
FIGURE 2-6. STATUS PORT OPTO-COUPLER ACTIVE “HIGH” CONFIGURATION
FIGURE 2-7. STATUS PORT OPTO-COUPLER ACTIVE “LOW” CONFIGURATION
BHK-MG (OPR) 032816 2-13/(2-14 Blank)
SECTION 3 - OPERATION
3.1 GENERAL
This section explains how to oper ate the BHK-MG Power Supply. The power supply can b e
operated either in Local mode using the front panel keypad and LCD (PAR. 3.2), or in Remote
mode using either SCPI commands via the GPIB bus (PARs. 3.3, 3.5) or analog programming
via the rear panel terminals (PAR 3.6). Remote analog programming can be combined with
either local programming using the front panel keyboard or remote programming using SCPI
commands via the GPIB bus.
3.2 LOCAL MODE OPERATION
Local operation of the BHK-MG Power Supply is accomplished via the 24 key keypad on the
front panel. All indications are provided by the 2-line LCD. Local mode operation includes a
description of the interaction between the LCD and the front panel keypad. Each key of the front
panel is described, with a reference to a paragraph detailing the use of that key.
3.2.1 FRONT PANEL KEYPAD AND LCD. (SEE FIGURE 2-1)
The front panel keypad is comprised of 24 keys, 13 dedicated to command functions, five dedicated to data functions, and six keys that have both command and data functions. When the
power supply is in command entr y status th e com man d func tions are effective; whe n th e po wer
supply is in data entry status the data functions are effective.
3.2.1.1 COMMAND ENTRY STATUS
Indicated by blinking colon (:) on bottom line of LCD; the power supply is waiting for a command
to be entered. Valid command entry is accompanied by a brief audible beep; data will not be
accepted (accompanied by longer audible buzz). The LCD indicates the actual voltage and current at the output terminals. When the output is disabled (LCD bottom line reads Output OFF),
the power supply is in Command entry status even though the blinking colon is not visible.
NOTE: The blinking colon is indicated by (:_:_:) in this manual.
3.2.1.2 DATA ENTRY STATUS
Indicated by blinking equal sign (=); the power supply is waiting for data to be entered. Valid
data entry is accompanied by a brief audible beep; commands will not be accepted (accompanied by longer audible buzz). Enter new value (the key erases data entered). Press ENTER
to accept new setting, or CLEAR to exit without changing setting.
NOTE: The blinking equal sign is indicated by (=_=_=) in this manual.
3.2.1.3 DISPLAY (LCD)
The LCD is a 2-line display with a capacity of 16 characters per line. The info rmation is gener ally
arranged as shown in Table 3-1 (information that does not follow this format is self-explanatory).
BHK-MG (OPR) 032816 3-1
TABLE 3-1. LCD MESSAGES
LOCATION MESSAGE DESCRIPTION
Top left Loc/Rem Digital control status: either Remote or Local
top right CV/CC Constant voltage mode/constant current mode
Bottom
left:
Top or Bottom middle: (=_=_=) Data entry status
Bottom
right:
in command entry n.nV Actual output voltage
In data entry (parameter) e.g. OVset if OV SET key was pressed.
Bottom middle: (:_:_:) Command entry status
in command entry n.n mA Actual output current.
In data entry n.n V or n.n mA Present programmed value of parameter, replaced by data entered.
3.2.1.4 KEYPAD FUNCTIONS
Keypad functions are listed in Table 3-2. Six keys have dual functions, depending on whether
the power supply is in command entry status (waiting for a command to be entered), or data
entry status (waiting for a number to be entered). Command entry status is indicated by a blinking colon (:_:_:) and data entry status is indicated by a blinking equal sign (=_=_=).
NOTE: Keys with dual functions are labeled with both a command and a number. The com-
mand label is referred to when the unit is in (:_:_:) command entry status; the number is referred to when the unit is in (=_=_=) data entry status.
KEY
OUTPUT
ON/OFF
V SET Command Entry
I SET Command Entry
LOCAL Command Entry
RESET Command Entry
POWER SUPPL Y
STATUS ACTIVE
Command Entry
TABLE 3-2. KEY FUNCTIONS
DESCRIPTION
If top line of LCD reads Digital is OFF, press to enable the output. If output is on,
press to disable the output controlled by digital means (keypad or GPIB setting).
If analog control used, analog input must be turned off separately to disable the
output.
Press to set output voltage. After V SET is pressed, previous setting is displayed. Data entry required to enter new value of output voltage; press ENTER
to accept displayed value.
Press to set output current. After I SET is pressed, previous setting is displayed.
Data entry required to enter new value of output current; press ENTER to accept
displayed value.
If the power supply is in remote mode, keypad is disabled except for LOCAL
key. Press to enable keypad. If LCD reads KEYPAD LOCKED, the LOCAL key
is also disabled and can only be unlocked by remote operation.
Press to restore the power on default values: CV mode, output voltage = 0, output current value chosen from the POWER-UP OR RESET CURRENT submenu, overvoltage and overcurrent values per Table 1-2.
REFERENCE
PARAGRAPH
3.2.7
3.2.9
3.2.9
3.2.4, B.84
3.2.8
3-2 BHK-MG (OPR) 032816
TABLE 3-2. KEY FUNCTIONS (CONTINUED)
KEY
MENU Command Entry
OV SET
7
OC SET
8
CALIB
9
POWER SUPPL Y
STATUS ACTIVE
Command Entry
Data Entry
Command Entry
Data Entry
Command Entry
Data Entry
DESCRIPTION
Press to enter Menu commands: press repeatedly to scroll through Menu functions: (1) set LCD contrast, (2) GPIB address, (3) Baud Rate, (4) Loop Back
Test, (5) DCL control, (6) Power-Up Digital DC Output on/off, (7) speaker on/off,
(8) change calibration password, (9) restore previous calibration values,
(10) restore factory calibration values, (11) view firmware version number,
(12) set Power-up and RESET current, (13) set maximum voltage, (14) set maximum current, (15) current scale. Press ENTER, RESET or CLEAR to exit
Menu.
Press to set overvoltage protection value. Data entry required to enter the overvoltage protection value; press ENTER to accept displayed value.
Press to enter number 7. 3.2.1.2
Press to set overcurrent protection value. Data entry required to enter new overcurrent protection value; press ENTER to accept displayed value.
Press to enter number 8. 3.2.1.2
Press to enter Calibration status. Requires password entry; instructions appear
on LCD.
Press to enter number 9. 3.2.1.2
REFERENCE
PARAGRAPH
(1) 3.2.5,
(2) 3.3.3,
(3) 3.4.1
(4) 3.4.4
(5) 3.3.2
(6) 3.2.7.4
(7,)3.2.6,
(8) 4.5,
(9) 4.6,
(10) 4.7
(11) 3.2.15
(12) 3.2.8.1
(13, 14) 3.2.12,
(15) 3.2.10
3.2.11
3.2.11
4.3
STORE Command Entry
EDIT
PROG
STEP
4
TIME
5
RUN
6
RECALL Command Entry
CLEAR Data Entry
1 Data Entry
Command Entry
Command Entry
Data Entry
Command Entry
Data Entry
Command Entry
Data Entry
Press to store present values of output voltage and current and overvoltage and
overcurrent protection. Data entry required to select memory location where values are to be stored
Press to select the starting memory location to be edited. Then use or to
view or modify the parameters of a specific memory location or to create a new
program.
Press to select starting address of program to be executed one step at a time.
Address is updated each time STEP is pressed.
Press to enter number 4. 3.2.1.2
Press to edit time value for specific memory location. Select memory location
(data entry), then enter time value, 0.01 to 655.35 seconds (data entry).
Press to enter number 5. 3.2.1.2
Press to run a program. Requires data entry to select starting location. Press
ENTER to accept displayed value.
Press to enter number 6. 3.2.1.2
Press to recall previously stored values of output voltage and current, and overvoltage and overcurrent protection. The previously stored output state (enabled
or disabled) will also be recalled. Data entry required to select memory location
containing values to be recalled; press ENTER to accept displayed value.
Press to exit Data Entry status; any numbers entered are lost. Restores Command Entry status
Press to enter number 1. 3.2.1.2
3.2.13
3.2.16.1
3.2.16.3
3.2.16.1.1
3.2.16.2
3.2.14
3.2.9
BHK-MG (OPR) 032816 3-3
TABLE 3-2. KEY FUNCTIONS (CONTINUED)
KEY
2Data Entry
3Data Entry
ENTER Data Entry
0Data Entry
( . ) Data Entry
POWER SUPPL Y
STATUS ACTIVE
Command Entry
Data Entry
Command Entry
Data Entry
DESCRIPTION
Press to enter number 2. 3.2.1.2
Press to enter number 3. 3.2.1.2
Press to accept data entered and return to Command Entry status. 3.2.9
— In CV (constant voltage), press to decrease output voltage by increment
equal to voltage resolution (0.025% of EOmax).
— In CC (constant current), press to decrease output current by increment
equal to current resolution (0.025% of IOmax).
— In EDIT PROG status, changes the parameter displayed on LCD for a specific memory location and decrements memory location displayed on LCD.
Erases number to left, or decreases value shown (e.g. Display Contrast setting). 3.2.9
Press to enter number 0. 3.2.1.2
Press to enter decimal point 3.2.1.2
— In CV (constant voltage), press to increase output voltage by increment equal
to voltage resolution (0.025% of EOmax).
— In CC (constant current), press to increase output current by increment equal
to current resolution (0.025% of IOmax).
— In EDIT PROG status, changes the parameter displayed on LCD for a specific memory location and increments memory location displayed on LCD
Increase value shown. 3.2.5
REFERENCE
PARAGRAPH
3.2.9, 3.2.16.1
3.2.9, 3.2.16.1
3.2.2 TURNING THE POWER SUPPLY ON
CAUTION: DO NOT REPEATEDLY TOGGLE THE CIRCUIT BREAKER/SWITCH AS THIS
MAY CAUSE UNIT TO FAULT. ALLOW THE UNIT TO BE OFF FOR AT LEAST
THREE (3) SECONDS BEFORE TURNING THE UNIT BACK ON TO GIVE THE
POWER LOSS CIRCUIT TIME TO RESET.
Set Power ON/OFF circuit breaker/switch on front panel to the up position to turn the power supply on. If actuator does not lock when released, wait a few seconds before trying again. The circuit breaker is “trip-free” design; if overload exists or the protection is activated, contacts cannot
be held closed by actuator. Setting the circuity breaker/switch to the down position shuts the
power supply off.
When the power supply is turned on, the LCD briefly displays self test messages, then displays
the power supply type on the top line (e.g., Kepco BHK 500) and GPIB addr. = nn on the
bottom line, where BHK 500 is model BHK 500-0.4MG and nn is the GPIB address (factory
default GPIB address = 6). After a few seconds, the bottom line of the LCD displays the voltage
and current at the BHK-MG output. The top line displays either OFF or the current status of the
unit as shown in Figure 3-1. The status of the unit upon power-up can be changed using the
MENU key as detailed in PAR. 3.2.7.4. Power on defaults also include setting maximum values
for overcurrent and overvoltage protection (PAR. 1.4.4), but are not displayed. If the unit fails a
self-test, the LCD shows the last successful operatio n, an d the unit be eps continua lly.
If the unit fails self-test during power-up, error messages are shown on the LCD. The failure will
usually cause the test to be repeated, and if the unit passes the second test, power-up continues and the error message disappears . Refe r to PAR. 3.2.3 for details.
3-4 BHK-MG (OPR) 032816
3.2.3 ERROR CONDITIONS
Loc OFF
0.000A0.000V (:_:_:)
NOTE: (:_:_:) indicates blinking colon (:), Command Entry status
(=_=_=) indicates blinking equal sign (=), Data Entry status
**** indicates previously set current scale. High indicates high range, Low indicates low range.
Loc CV
0.000A0.000V (:_:_:)
(a) Default Display State for OUT OFF
@ Pwr-Up Selection (PAR. 3.2.7.4)
(b) Default Display State for OUT ON
at Pwr-Up Selection (PAR. 3.2.7.4)
I****
I****
Refer to Table 3-3 for how to proceed if any of the error conditions listed appear on the LCD for
more than 90 seconds. For some errors the firm ware repe ats the action, and if the ne w attemp t
is successful, the error message will be deleted and normal operation will proceed.
LCD DISPLAY SHOWS ACTION
When the microprocessor is not able to complete its power up
sequence, it is possible that uncontrolled high output voltage may be
present at the output. Turn off power supply immediately and disconnect any load. Measure the output using a voltmeter set to measure
the maximum voltage that can be delivered by the power supply.
PROM FAILS CHECK Refer unit for service by authorized personnel.
RAM FAILS CHECK Refer unit for service by authorized personnel.
NvRAM & Dpot Err Restore Factory Calibration as described in PAR. 4.7, then verify that the
NVRAM STATUS ERROR Restore Factory Calibration as described in PAR. 4.7, then verify that the
PAGE FAILS CHECK Refer unit for service by authorized personnel.
CNFG FAILS CHECK Restore Factory Calibration as described in PAR. 4.7, then verify that the
Completely blank, or a blinking
underline in the upper left corner
FIGURE 3-1. LCD POWER ON DEFAULTS
TABLE 3-3. ERROR CONDITIONS
WARNING
programmed voltage output is accurate. If problem continues, refer unit for
service by authorized personnel.
programmed voltage output is accurate. If problem continues, refer unit for
service by authorized personnel.
programmed voltage output is accurate. If problem continues, refer unit for
service by authorized personnel.
Refer unit for service by authorized personnel.
3.2.4 SETTING LOCAL MODE
When the power supply is turned on, it is automatically set to Local mode. If remote commands
are accepted over the GPIB bus, the power supply will automatically go into Remote mode (Rem
at the upper left of the LCD). Pressing the LOCAL key will restore Local mode. When in Remote
mode, all keys except LOCAL are disabled.
BHK-MG (OPR) 032816 3-5
The BHK-MG incorporates a “keypad lockout” command which allows the LOCAL key to be disabled during remote operation, preventing inadvertent setting of the power supply to Local
mode. When the keypad is locked, the LCD displays RwL in place of LOC. If the keypad is
locked, it must be unlocked either by a remote command (see Appendix B, PAR. B.84), or
cycling the power supply off then on.
3.2.5 ADJUSTING LCD CONTRAST
With the power supply in command entry status (:_:_:), press MENU key until LCD displays
CONTRAST. Press or key to increase or decrease contrast for optimum viewing. The con-
trast can also be set directly by entering a number from 0 to 9. Press ENTER or CLEAR to exit
menu.
3.2.6 ENABLING/DISABLING AUDIBLE BEEPS
With the power supply in command entry status (:_:_:), press MENU key until LCD displays
SPEAKER. The top line indicates if the speaker is on or off (the factory default setting is speaker
on). Enter 1 to enable the speaker, or 0 to disable the speaker. Press ENTER or CLEAR to exit
menu. Audible beeps associated with safety or failure messages are always enabled and can
not be disabled.
3.2.7 ENABLING/DISABLING DC OUTPUT POWER
When the power supply is turned on, the output is automatically disabled or enabled depending
on OUT on or off @Pwr-Up (see PAR. 3.2.7.4), and the bottom line of the LCD gives voltage
and current measurements at the output.
3.2.7.1 DISABLING DC OUTPUT WHEN USING DIGITAL INPUTS ONLY (KEYPAD AND/OR GPIB)
To disable the output, press the red OUTPUT ON/OFF key; the top line of the LCD reads: OFF
and the bottom line displays output voltage and current (zero). When the output is disabled, voltage and current are programmed to zero; the power supply remains in Command Entry status.
Pressing the OUTPUT ON/OFF key again enables the output: the previously programmed values of voltage and current are restored and the LCD displays the mode (CV or CC) and actual
values of output voltage and current.
3.2.7.2 DISABLING DC OUTPUT WHEN USING ANALOG CONTROL.
If analog control is used without digital programming, simply set the analog input to a value that
brings the output voltage and current to zero without pressing the OUTPUT ON/OFF key.
To disable the output if both analog and digital (keypad and/or GPIB) control are used, first
press the red OUTPUT ON/OFF key; the top line of the LCD reads: OFF and the bottom line displays output voltage and current controlled by analog means. Set the analog input to a value
that brings the output current and voltage to zero. Pressing the OUTPUT ON/OFF key again
enables the output: the previously programmed values of voltage and current (from the keypad
or GPIB) are restored and the LCD displays the mode (CV or CC) and actual values of output
voltage and current. Analog inputs must be restor ed sep arate ly to return to the ou tput settings in
effect when the output was disabled.
After disabling the output by pressing the OUTPUT ON/OFF key, if the analog input is causing
more than approximately 8Vd-c to appear at the output terminals, or if cu rrent is be ing supp lied
to the load exceeds approximately 0.3% of full scale for the selected range, the unit will beep
and enter a controlled shutdown for safety purposes. Shutdown can be avoided by setting the
analog input to a value that brings the BHK-MG output below 8Vd-c and output current to less
3-6 BHK-MG (OPR) 032816
than 0.3% of full scale for the selected range within 25 seconds. For 15 seconds, the top line of
the LCD alternately flashes the messages DIGITAL IS OFF and SET ANALOG OFF, while the
bottom line of the LCD shows the actual output voltage and current. After 15 seconds, the bottom line will alternate a message showing the time remaining before shutdown (e.g POWER OFF
9 SEC) with the message SET ANALOG OFF . After the 10 second countdown the front panel circuit breaker will trip. (If (due to a defective protection circuit or faulty circuit breaker) the unit
does not shut down, the LCD displays **BHK** **FAILURE ** and beeps constantly.)
3.2.7.3 REMOTE SHUTDOWN USING EXTERNAL TRIGGER PORT
A temporary short between pin 2 and pin 1 of the External Trigger port (or if pin 2 is at TTL logic
1, applying a temporary logic 0 to pin 2 referenced to pin 1) produces a shutdown signal which
immediately shuts down the power supply output, and voltage and current are set to zero (0
LSB for voltage, and power up and reset value (see PAR. 3.2.8.1) for current). The DCL Control
setting (see PAR. 3.3.2) determines the output settings when the output is reenabled: either
restored to the voltage/current settings in effect at the time shutdown was initiated (“output
unchanged”) or voltage and current still programmed to zero (“output = 0”).
NOTE: Turn off power to the unit or disable the output before inserting the plug in the External
Trigger port to avoid unintentionally initiating shutdown or trigger.
3.2.7.4 POWER UP DC OUTPUT CONTROL
The output of the power supply can be programmed to be either enabled or disabled upon
power-up. With the power supply in comma nd entry status (:_:_:), pres s the MENU key until
LCD displays Out off @Pwr-Up or Out on @Pwr-Up. indicating whether the Digital DC Output will be on (enabled) or off (disabled) upon power-up. Press 1 to enable the Digital DC Outp ut
upon power up. This sets the output to zero volt and current to the Power-up and Reset current
value. Press 0 to disable the output upon power up. Press CLEAR or RESET to exit menu and
return to command entry status.
3.2.8 RESET OPERATION
RESET overrides all other local commands to reset the power supply to the power on defaults:
output voltage set to zero, output current set to the value specified as the power-up and reset
current (see PAR. 3.2.8.1), overcurrent and overvoltage protection set to the maximum values
per PAR. 1.4.4. The output is either enabled or disabled, as determined by the front panel DCL
Control setting (enabled for “output = 0,” disabled for “output unchanged”) see PAR. 3.3.2 for
details. The default configuration is for RESET to disable the output (output OFF). The power
supply remains in command entry status. The current scale remains unchanged.
3.2.8.1 SETTING POWER-UP & RESET CURRENT
The factory setting of the power-u p and reset current is 1.28% of Io max. This ins ures that the
power supply is in voltage mode when the unit is initially turned on or a reset occurs. The user
can change this value to be from 0 to 10% of the unit’s rated current. To change this setting,
ensure the unit is in command entry status (:_:_:) and press the MENU key until the top line
of the display presents the message PWR-UP & RESET and the bottom line shows ISET =
n.n ma, where n.n is the present value of power-up and reset current. Press
leave the value unchanged. Press number keys followed by the ENTER key to validate a new
value (the key erases data just entered) or CLEAR to exit without changing the setting.
If the value entered is higher than 10% of the rated current for the power supply, the bottom line
of the LCD flashes Iset MAX = xx where xx = Iomax/10 (e.g., for BHK500-0.4MG, xx =
40.0mA). The unit remains in data entry status (=_=_=) waiting for a value equal to or less than
the 10% of rated current.
MENU key to
BHK-MG (OPR) 032816 3-7
3.2.9 SETTING OUTPUT VOLTAGE OR CURRENT
V SET and I SET set output voltage and current limit, respectively, when the unit is in constant
voltage (CV) mode and set voltage limit and output current, re spectively, when the unit is in constant current (CC) mode. The mode (CV or CC) is determined by the load together with the programmed settings. As long as the voltage across the load produces a current that is less than
the I SET value, the unit operates in CV m ode (volt age programme d to V SET value, current limited by I SET value). If the load changes to the point that current through the load reaches the I
SET value, the unit automatically enters CC mode (current programmed to I SET value, voltage
limited by V SET value).
With the power supply in command entry status (:_:_:), press V SET (voltage) or I SET (current) key to put the power supply in data entry status (=_=_=). The lower right side of the LCD
shows the programmed setting in effect when the key is pressed. Press ENTER or CLEAR to
exit without changing setting. Enter new value (the key erases data just entered) and press
ENTER to accept new setting or CLEAR to exit without changing setting.
NOTE: Although the LCD can display up to five decimal places, only two decimal places are
actually used for voltage and current settings (except that only one decimal place is
used for setting voltage on Models BHK 1000-0.2MG and BHK 2000-0.1MG, and three
decimal places are used for setting current on all models when current scale is set to
Low range.).
With the power supply in command entry status (:_:_:), an alternative is to use key
(increase) or key (decrease) to change the output by the minimum increment (0.025% of
E
max for voltage, 0.025% of IOmax for current). In CC mode, these keys control output cur-
O
rent; in CV mode they control output voltage. When the unit switches fr om const ant curren t (CC)
to constant voltage (CV) mode, or from CV to CC mode the and keys are reassigned to
the active parameter. Once the transition point is reached, each press of the key increases
voltage, then current, changing the mode, from CV to CC or from CC to CV. The key has no
effect after the maximum (or programmed limit) has been reached. If the value entered exceeds
the maximum setting, the LCD bottom line flashes VsetMAX=n.n V or IsetMAX=n.n mA
where n.n is the maximum setting (see PAR.3.2.12). The unit returns to {=_=_=) waiting for a
value that does not exceed the maximum.
3.2.10 CHANGING CURRENT SCALE
The full scale output current can be changed from the maximum current rating (factory default)
of the power supply (I
max) to a value ten times less (IOmax/10): e.g., for the BHK 500-0.4MG
O
power supply the full scale current can be eithe r 400mA or 40mA. The relative accuracy and
resolution are the same for both current programming scales because the power supply has two
independent sensing resistors and the calibration is done separately; relative readback accuracy and resolution are ten times better for I
The current scale setting is stored in non-volatile memory and retained when the unit is turned
off. When the unit is turned on, the stored current scale setting is in effect.
When the current scale is changed, the output is automatically turned off to avoid transients at
the output. After the scale has bee n cha nged, p ress OUTPUT ON/OFF key to en ab le the ou tp ut
and restore the settings of the new current scale. Reprogram output voltage and current if the
RESET key was pressed,
3-8 BHK-MG (OPR) 032816
max/10 scale.
O
With the power supply in command entry status (:_:_:), press MENU until the top line of the
display presents the message FS CURRENT (=_=_=) <n> mA, where <n> represent the
actual full scale of the current (I
ENTER or CLEAR to exit menu without chang ing s et ting . Pr ess 1 key to toggle between I
and I
max/10; press ENTER to accept new full scale current and exit menu or CLEAR to exit
O
max or IOmax/10); the bottom line reads 1=TOGGLE. Press
O
O
max
without change.
When the full scale current is changed from High (I
• programmed current value remains unchanged if it is less than or equal to the Low
maximum current, otherwise it is automatically limited to the Low maximum value.
• programmed overcurrent protection value remains unchang ed if it is le ss t han or eq u al
to 1.1 x Low maximum current, otherwise it is automatically limited to (1.1 x Low maximum).
• maximum current value (PAR. 3.2.12) is restored.
• voltage and overvoltage protection settings are unchanged.
• the 40 nonvolatile memory locations for Low range are active.
• Trigger, power up and reset current are divided by 10.
When the full scale current is changed from Low (I
• programmed current value remains unchanged if it is less than or equal to the High
maximum current, otherwise it is automatically limited to the High maximum value.
• programmed overcurrent protection value remains unchang ed if it is le ss t han or eq u al
to 1.1 x High maximum current, otherwise it is automatically limited to (1.1 x High maximum).
• maximum current value (PAR 3.2.12) is restored from saved value
• voltage and overvoltage protection settings are unchanged.
• the 40 nonvolatile memory locations for High range are active.
• Trigger, power up and reset current are multiplied by 10.
max) to Low (IOmax/10):
O
max/10) to High (IOmax):
O
NOTES: 1. When changing from High to Low or Low to High range, even though the settings
for current and overcurrent are theoretically unchanged, they may actually be in
error by up to 0.15% of full scale current due to rounding errors. To improve accuracy it is recommended that current and overcurrent be set using the keypad after
changing range.
2. Changing current scale is not permitted when running a program (see PAR. 3.2.16).
All steps must use the same current scale.
3.2.11 SETTING OVERVOLTAGE OR OVERCURRENT PROTECTION
With the power supply in command entry status (:_:_:), press OV SET (overvoltage) or OC
SET (overcurrent) to put the power supply in data entry status (=_=_=). The lower ri ght side of
the LCD shows the programmed setting in effect when the key is pressed. Press ENTER or
CLEAR to exit without changing setting. Enter new value and press ENTER to accept new set-
ting (the key erases data just entered), or CLEAR to exit without changing setting.
BHK-MG (OPR) 032816 3-9
The value for overvoltage protection can be set within the range of 0 to 1.1 x EOmax; overcurrent can be set within the range of 0 to 1.1 x I
for overvoltage protection and 1.1 x I
max for overcurrent protection.
O
max. The factory default values are 1.1 x EOmax
O
NOTE: Although the LCD can display up to five decimal places, only two decimal places are
actually used for voltage and current settings (except that only one decimal place is
used for setting voltage on Models BHK 1000-0.2MG and BHK 2000-0.1MG, and three
decimal places are used for setting current on all models when current scale is set to
Low range.).
3.2.12 CHANGING MAXIMUM VOLTAGE OR CURRENT VALUE
The default maximum values of voltage and current are determined by the model, e.g., 500V
and 400mA for the BHK 500-0.4MG. These values can be lowered by the user to prevent inadvertent damage to a specific circuit under test by establishing software limits through the use of
the MENU key. Lowering the maximum values of the BHK 500-0.4MG to 100V and 200mA,
effectively makes the unit a 100V/200mA power supply.
Maximum values for current are independent for Low Range and High Range (see PAR.
3.2.10). With the power supply in co mmand entry status (:_:_:), press MENU key until the
LCD reads New MAXIMUM Vset (or Iset) (=_=_=) n.n where n.n is the maximum value
setting to be changed (V for voltage, mA for current). Press CLEAR to exit menu without changing setting. Press ENTER to validate displayed value or press number keys to enter new value
and press ENTER to accept new setting (the key erases data just entered), or CLEAR to exit
without changing setting.
NOTE: Although the LCD can display up to five decimal places, only two decimal places are
actually used for voltage and current settings (except that only one decimal place is
used for setting voltage on Models BHK 1000-0.2MG and BHK 2000-0.1MG, and three
decimal places are used for setting current on all models when current scale is set to
Low range.).
If a value is entered that is higher than the rated maximum for the power supply, the bottom line
of the LCD flashes Vset or Iset MAX = <Eomax or Iomax> where E
rated maximum of the power supply. The unit remains in data entry status (=_=_=) waiting for
a value equal to or less than the maximum value. Press CLEAR to exit without changing the
value.
Once the maximum value has been changed, if a value higher than the new maximum is
attempted to be programmed, the LCD flashes Vset (or Iset) MAX = n.n where n.n is the
programmed maximum (V for voltage, mA for curren t).
NOTE: If the programmed output value is higher than the new maximum value established
with the MENU key, the output will be automatically limited to the new maximum value.
3.2.13 STORING POWER SUPPLY OUTPUT SETTINGS
The programmed settings of voltage, current, overvoltage protection and overcurrent protection
can be stored in one of the 40 memory locations available for local programming (see PAR.
3.2.16). To accommodate the two current scales, there are actually 40 locations for High range
max or IOmax is the
O
3-10 BHK-MG (OPR) 032816
and 40 locations for Low range which are swapped each time the rang e i s chang ed, so that only
one set of 40 locations is active, depending on the current scale selected.
With the power supply in command entry status (:_:_:), press STORE key. The LCD reads
STORE mem (=_=_=) nn where nn is the memory location where the settings are to be
stored. Press CLEAR to exit without changing setting. Press ENTER to validate the existing
location. Enter memory location (from 1 to 40) and press ENTER. The programmed voltage,
current, overvoltage protection and overcurrent protection settings in effect when ENTER is
pressed are stored in the selected memory location. To recall stored settin gs, see PAR. 3.2.14.
The default value at power-up for the Store command is 01. During normal operation, the location last used is displayed.
3.2.14 RECALLING STORED OUTPUT SETTINGS
With the power supply in command entry status (:_:_:), press RECALL. The LCD reads
RECALL mem (=_=_=) nn where nn is the memory location holding the settings to be
retrieved. Note that the location retrieved will correspond to the active current scale. The 40
memory locations are different for High and Low range (see PAR. 3.2.13). Press CLEAR to exit
without changing setting. Press ENTER to validate the existing location. Enter memory location
(from 1 to 40) and press ENTER. The stored settings for voltage, current, overvoltage protection
and overcurrent protection replace the current values, and the unit returns to (:_:_:) command entry status. The default value at power-up for the Recall command is 01. During normal
operation, the location last used is displayed.
3.2.15 FIRMWARE VERSION
To display the firmware version of the power supply, the power supply must be in command
entry status (:_:_:). Press the MENU k ey until the LCD displays BHK XXXX,SSSSSS mm-
dd-yyyy,V.zz where XXXX indicates the power supply model (e.g. XXXX = 1000 for BHK
1000-0.2MG), SSSSSS indicates the serial number, mm-dd-yyyy indicates the factory calibration date and V. zz indicates the firmware version. Press ENTER or CLEAR to exit menu and
return to command entry status.
3.2.16 LOCAL MODE PROGRAMMING OF THE POWER SUPPLY.
Local mode programming offers the user 40 memory locations that can be used to program the
power supply. Each location defines values for output voltage, output current, overcurrent protection, overvoltage protection, time duration (between 0.01 and 655.35 seconds) for the programmed settings, and the address of the next memory location in the program. The factory
default values for all memory locations is: 0 Volt s, 0 Amperes, overvolt age and overcu rrent is set
to Eomax+10% and Iomax+10%, respectively, time duration is set to 0.01 Sec, and next step is
set to 0.
3.2.16.1 CREATING OR MODIFYING A PROGRAM (PROGRAM EDIT MODE)
Creating a program and modifying an existing program are identica l except th at a program modification requires only selected parameters to be changed rather than all new parameter values.
With the power supply in command entry status (:_:_:), press EDIT PROG key. The top line
indicates the STARTaddr.(=_=_=)nn, where nn is one of 40 memory location. To select a different address, enter new value and press ENTER.
BHK-MG (OPR) 032816 3-11
The top line of the LCD indicates the active memory location, e.g. ViewVAL Mem <n> where n
WARNING
is the memory location previously chosen. The bottom line of the LCD indicates the parameter
on the left (Iset, Vset, OVset, OCset, TIMEval, NEXT STEP), the parameter’s value on the
right, and data entry status (=_=_=) in the middle. To modify time values see PAR.3.2.16.1.1.
Press ENTER to accept displayed value, or enter new value and press ENTER to accept new
setting (the LCD displays the next parameter). Press CLEAR to exit Program Edit mode without
changing value. Use or key to scroll forward or backward to view next or previous parameter or memory location. For a program to run once, then stop, see PAR. 3.2.16.6; to cyc le a
program continuously, see 3.2.16.4. After all program values have been set, press CLEAR or
ENTER to exit Program Edit mode. Setting up a program can be made easier by copying the
Memory Location Worksheet (Table 3-5) and filling in the values before programming the power
supply.
3.2.16.1.1 MODIFYING PROGRAMMED TIME INTERVAL
The TIME key offers a quick an d easy way to change th e time for any memory locatio n. With the
power supply in command entry status (:_:_:), press TIME key. The LCD displays TIME@nn
(=_=_=) where nn is the current memory location of the TIME function. Press CLEAR to exit
without changing setting. Press ENTER to validate the existing location or enter the new location and then press ENTER. The display now shows TIMEval = n.n s where n.n is the time
value set for the selected location. The default time interval for all 40 steps is 0.01 second. Enter
new value (between 0.01 and 655.35 seconds) and press ENTER to accept new value or press
CLEAR to exit without changing value. The unit returns to command entry status (:_:_:).
3.2.16.1.2 TIME INTERVAL ACCURACY
The accuracy of the time interval is ±1% through the entire time interval range.
3.2.16.2 RUNNING A PROGRAM
With the power supply in command entry status (:_:_:), press RUN key. The LCD bottom line
indicates the start address of the program. Press ENTER key to run the program starting with
that address. To change the starting address, enter new value and press ENTER to run the program. Press CLEAR to exit without running the program.
When the program is running, the LCD displays th e actual volt age a nd curren t, however if all th e
steps are programmed for 0.01 second, the LCD reads *** RUNNING PROGRAM***.
3.2.16.3 STEPPING THROUGH A PROGRAM
Programmed voltage is present at th e output as steps are executed.
The STEP function is useful for examining a program that has just been created or edited before
running it in real-time. With the power supply in command entry status (:_:_:), press STEP
key. The LCD bottom line indicates the start address of the program; press ENTER to begin
stepping at that address. To change the starting address, enter new value and press ENTER to
begin stepping at the new address, press CLEAR to exit withou t ste ppin g thro ugh the prog ra m.
3-12 BHK-MG (OPR) 032816
TABLE 3-4. MEMORY LOCATION WORKSHEET
MEMORY
LOCATION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
I SET
(Current)
(mA)
V SET
(Voltage)
(V)
OCset
(Overcurrent
Protection)
(mA)
OV set
(Overvoltage
Protection)
(V)
TIMEval
(0. to 655.35)
(Sec)
NEXT STEP
(Next location
to execute)
BHK-MG (OPR) 032816 3-13
The LCD top line shows LOC to indicate local mode, aa bb where aa is the me mory loca tion
just executed, bb is the NEXT STEP location, and shows CV (constant voltage) or CC (constant
current) to indicate the actual operating mode. The LCD bottom line shows the output voltage
and current measurements for the location just executed, and (:_:_:) indicates command st a-
tus. Press STEP to execute location bb. The LCD will again display the location just executed,
voltage and current measurements, and the NEXT STEP location. Continue to press STEP to
execute the program one step at a time. The OUTPUT ON/OFF key can be used to turn the output on or off when in step mode.
Press CLEAR, or RESET to exit Step function: CLEAR keeps the output at the values established by that step (as permitted by the load). RESET restores the power on defaults (Figure 3-
1).
3.2.16.4 CYCLING A PROGRAM
To cycle a program, modify the program (see PAR. 3.2.16.1) and go to the last memory location
to be executed and set the NEXT STEP addre ss to the Starting address, causing the program to
loop and repeat indefinitely. For example, if the last location is 14, and the starting location is 05,
press EDIT PROG, enter 14, then press ENTER. Press until LCD reads ViewVAL Mem14
NEXT STEP (=_=_=). Enter 5 and press ENTER. When the program runs, it will start at loca-
tion 05, continue to 14, then loop back to the location 05, and repeat indefinitely.
3.2.16.5 RUNNING A PROGRAM ONCE
To set up a program to stop after running once , mod ify the pr ogr am (s ee PAR. 3.2.16.1) and go
to the last memory location to be executed and set the NEXT STEP address to 0. For example,
with the power supply in command entry status (:_:_:), press EDIT PROG. Enter the last
memory location you want executed (e.g. 14), then press ENTER. Press key until LCD reads
ViewVAL Mem14 NEXT STEP (=_=_=). Enter 0 and press ENTER. The program will now
stop after memory location 14 is executed. When the program stops, the power supply will continue to provide the output specified by the last location (in the above example, location 14).
3.2.16.6 STOPPING A RUNNING PROGRAM
There are three ways to stop a program that is running:
• Pre ss CLEAR key: the progra m stops after finishing the step (location) tha t was being
executed when the key was pressed. The power supply output remains at the values
specified by that step.
• Press RESET key: The program stops immediately and power on defaults are restored
(see PAR. 3.2.8).
• Press OUTPUT ON/OFF key: the output is disabled (programmed to zero) and the program immediately stops at the step (location) that was being executed when the key
was pressed. Pressing the OUTPUT ON/OFF key again restores the output to the values specified by the step in effect when the program was stopped.
3.2.16.7 SAMPLE PROGRAM
Table 3-5 shows a sample program designed to cycle continuously; if the NEXT STEP value for
location 3 is set to 00, the program will run once and stop.
3-14 BHK-MG (OPR) 032816
TABLE 3-5. SAMPLE PROGRAM (MODEL BHK-MG 500-0.4MG)
MEMORY
LOCATION
1 400 420 440 550 1.5 02
2 400 500 440 550 1.8 03
3 400 250 440 550 1.0 01
NOTE: For each cell of a program OC set and OV set must be at least 2% above the maximum values of voltage and cur-
rent expected at the load. The limit parameter (I set for voltage mode, or V set for current mode) must be at least 1%
above the maximum load current (for I set) or load voltage (for V set).
I SET
(Current)
(mA)
V SET
(Voltage)
(V)
OC set
(Overcurrent
Protection)
(mA)
OV set
(Overvoltage
Protection)
(V)
TIMEval
(0.01 to 655.35)
(Sec)
NEXT STEP
(Next location
to execute)
3.2.17 CALIBRATION
See Section 4.
3.3 REMOTE MODE PROGRAMMING USING SCPI COMMANDS VIA IEEE 488 (GPIB). BUS
BHK-MG Power Supplies may be programmed over a control bus using SCPI (Standard Commands for Programmable Instruments). SCPI provides a common lang uage conformin g to IEEE
488.2 for instruments used in an automatic test system. The control bus used must be the IEEE
488 standard communication bus (General Purpo se Interface Bus, GPIB). Refer to Table 2-1 for
input/output signal allocations.) Most powe r supply functions available from the keypad can be
programmed via remote commands, in addition to some that are not available from the keypad
(e.g. triggering, and local lockout).
This section includes a discussion of GPIB bus protocols (PAR. 3.3.1), instructions for changing
the GPIB address (PAR. 3.3.3), a discussion of the VISA (Virtual Instrumentation Software
Architecture) driver supplied with the unit (PAR. 3.3.5), followed by a detailed explanat ion of
SCPI programming (PAR. 3.5)
3.3.1 IEEE 488 (GPIB) BUS PROTOCOL
Table 3-6 defines the interface capabilities of the BHK-MG power supply (Talker/Listener) relative to the IEEE 488 (GPIB) bus (reference document ANSI/IEEE Std 488: IEEE Standard Digital
Interface for Programmable Instrumentation) communicating with a Host Computer—Controller
(Talker/Listener). Tables 3-7 and 3-8 define the messages sent to the BHK-MG, or received by
the BHK-MG, via the IEEE 488 bus in IEEE 488 command mode and IEEE 488 data mode,
respectively. These messages are enabled during the “handshake” cycle, with the BHK-MG
power supply operating as either a Talker or a Listener.
TABLE 3-6. IEEE 488 (GPIB) BUS INTERFACE FUNCTIONS
FUNCTION
Source Handshake SH1 Complete Capability (Interface can receive multiline messages)
Acceptor Handshake AH1 Complete Capability (Interface can receive multiline messages)
Talker T6
SUBSET
SYMBOL
Basic talker, serial poll, unaddress if MLA (My Listen Address) (one-byte
address)
COMMENTS
BHK-MG (OPR) 032816 3-15
TABLE 3-6. IEEE 488 (GPIB) BUS INTERFACE FUNCTIONS (CONTINUED)
FUNCTION
Listener L4 Basic listener, unaddress if MTA (My Talk Address) (one-byte address).
Service Request SR1
Remote/Local RL1
Parallel Poll PP0 No Capability
Device Clear DC1
Device Trigger DT1 Respond to *TRG and <GET> trigger functions.
Controller C0 No Capability
SUBSET
SYMBOL
Complete Capability. The interface sets the SRQ line true if there is an
enabled service request condition.
Complete capability. Interface selects either local or remote information. In
local mode the BHK-MG executes front panel commands, but can be set to
remote mode via IEEE 488 bus. When in Remote mode all front panel keys
are disabled except LOCAL. LOCAL key can be disabled using keypad
lockout command (see Appendix B, PAR. B.84) so that only the controller
or a power on condition can restore Local mode.
Complete Capability. BHK-MG accepts DCL (Device Clear) and SDC
(Selected Device Clear).
COMMENTS
TABLE 3-7. IEEE 488 (GPIB) BUS COMMAND MODE MESSAGES
MNEMONIC
MESSAGE
DESCRIPTION
COMMENTS
DCL Device Clear Received
GET Group Execute Trigger Received
GTL Go To Local Received
IFC Interface Clear Received
LLO Local Lockout Received
MLA My Listen Address Received
MTA My Talk Address Received
OTA Other Talk Address Received (Not Used)
RFD Ready for Data Received or Sent
SDC Selected Device Clear Received
SPD Serial Poll Disable Received
SPE Serial Poll Enable Received
SRQ Service Request Sent
UNL Unlisten Received
UNT Untalk Received
3-16 BHK-MG (OPR) 032816
TABLE 3-8. IEEE 488 (GPIB) BUS DATA MODE MESSAGES
MNEMONIC MESSAGE DESCRIPTION COMMENTS
DAB
END
EOS
RQS
STB
3.3.2 DCL CONTROL
The device clear (DCL) and select ed device clear can be set to operate in tw o modes. In the
“output = 0” mode, when the device clear is received the output is disabled; when the output is
enabled, the output of the power supply is set to zero volts and current is set to the power-up
and reset current value (see PAR. 3.2.8.1). In the “output unchanged” mode sending DCL or
selected DCL disables the output, but has no ef fect on ou tput volt age and cur rent as required by
IEEE specification 488.2 so that when the output is enabled, the settings in effect when DCL
was issued are restored. Note that the DCL se tting also affects the operation of RESET (see
PAR. 3.2.8). The factory default value is “output=0” mode.
To change the DCL mode the unit must be in command entry mode (:_:_:), then depress the
MENU key until the top line of the display shows the current setting: either DCL OUTP = 0 or
DCL = OUTP UNCHNG. Depress 1 for “output unchanged” mode where the output is unaffected
by DCL; depress 0 for “output = 0V” mode where DCL sets the output to 0 volts and current is
set to the power-up and reset current value (see PAR. 3.2.8.1).
Data Byte Received or Sent
End Received or Sent
End of String Received or Sent
Request Service Sent
Status Byte Sent
3.3.3 CHANGING THE GPIB ADDRESS
When the power supply is in command entry status (:_:_:), press MENU key until the top line
of the LCD indicates the current GPIB address. Enter new value and press ENTER to accept
new setting, or CLEAR to exit without changing setting. The GPIB address default value is set
to 6.
3.3.4 EXTERNAL TRIGGER
The External Trigger Port can be used to restore the power supply output to settings previously
defined using SCPI commands. This can be done by applying a temporary short between pin 4
and pin 1 of the External Trigger Port, (or if pin 4 is at TTL logic 1, applying a temporary logic 0
to pin 4 referenced to pin 1).
NOTE: Turn off power to the unit or disable the output before inserting the plug in the External
Trigger port to avoid unintentionally initiating shutdown or trigger.
The following remote SCPI commands must be sent before the external trigger at pin 4 activated:
• The values to be set upon receiving the external trigger at pin 4 must be programmed
using VOLT:TRIG (PAR B.58) and CURR:TRIG (PAR B.48) commands.
BHK-MG (OPR) 032816 3-17
• Choose external trigger source by sending TRIG:SOUR EXT (PAR. B.92)
• Choose continuous action (by sending INIT:CONT ON (PAR B.12).
NOTE: The output must be enabled prior to activating the external tr igger at pin 4 of the External
Trigger port in order for the external trigger to work properly.
3.3.5 BHK-MG VISA INSTRUMENT DRIVER
The VISA instrument driver simplifies programming with a VISA compatible GPIB controller. and
Includes 1) source code (C) for all VISA functions, and 2) a complete programming reference
manual which can be used to program one or more BHK-MG power su pplies using a virtual front
panel observed on a computer monitor.
Download the latest VISA driver from the Kepco website at
http://www.kepcopower.com/drivers.htm
Although the software drivers supplied by Kepco are VISA compliant, they also require the
installation of the proper 32-bit VISA driv er fro m your GP IB car d supplier. Many vendors supply
this software with the hardware; National Instru me nts (http://www.natinst.com) has the driver for
their cards available on the internet at a file transfer site (ftp://ftp.natinst.com — find the folder
for support and VISA drivers). The driver to be installed is the win16 driver, even if your system
is running under Windows 95 or Windows NT.
3.3.6 PROGRAMMING TECHNIQUES TO OPTIMIZE PERFORMANCE
3.3.6.1 PROGRAMMING VOLTAGE/CURRENT LIMIT AND CURRENT/VOLTAGE LIMIT
Kepco's auto-crossover digital supplies can operate in either voltage mode with current limit, or
current mode with voltage limit. The operating mode is determined by the voltage and current
commands received, as well as the load. Each time voltage and current commands are
received, the unit must evaluate the commands and the load conditions to determine the proper
operating mode. Reducing the number of times this evaluation must be made is desirable
because Kepco's digital auto-crossover supplies employ two separate feedback loops. Each
time there is a potential mode change, there is always an uncontrolled period of a few milliseconds while the two feedback loops compete for control of the output. By changing only the
active parameter (e.g., voltage for voltage mode), there is no doubt as to what the operating
mode will be, so the unit is never uncontrolled, response is quick and no transients are possible.
Recommended programming techniques are:
1. Minimize programmed mode (voltage or curre nt) change s. Unle ss ab solutely re quir ed by the
test parameters, allow the power supply to automatically switch modes as determined by the
load. This will improve response time and reduce undesirable transients. For those power
supplies that employ relays (Kepco's MBT with “R” option, MAT and MST) this will also
increase the life of the relay.
2. Once the mode (voltage or current) is pr ogrammed, program the active parameter to zero
and the complementary limit parameter to the maximum anticipated for application. Then
program only the active parameter. The active parameter is the parameter that controls the
output, e.g., voltage controls the output in voltage mode.
3-18 BHK-MG (OPR) 032816
3. Never program both the active and co mple mentary limit parameter to zero. This can result in
long response times. Set the active parameter to zero and the complementary limit parameter to a minimum, e.g., 10% of maximum, to ensure that the active mode is defined.
3.3.6.2 MAKING SURE THE PREVIOUS COMMAND IS COMPLETE
Some SCPI commands require a flash memory update and can take an indeterminate amount
on time to complete. These commands are:
•*SAV
•CAL:SAVE
• SOUR:CURR :LIM
• SOUR:VOLT:LIM
• SYST:COMM:GPIB:ADDR
• SYST:COMM:SER:BAUD
• SYST:COMM:SER:ECHO
• SYST:COMM:SER:PACE
• SYST:COMM:SER:PROMpt
• SYST:PASS:NEW
• SYST:SEC:IMM
When sending these via the GPIB, these commands require a query to be added to the command string to verify the previous command is complete. When the command is complete, the
unit updates the status byte and indicates MAV (Messa ge Available, bit 4 - see Table A-3) is
true. MAV indicates that there is a response to be received by the computer, so when it
becomes set, the unit is ready for its next command after reading back the data from the query
that was added to the command string.
When sending the above commands via the RS 232 bus, data flow control must be enabled
(XON) using the SYST:COMM:SER:PACE command (see PAR. B.77) must be enabled for the
unit to properly update flash memory.
The *OPC? query is ideal to check if the previous command is complete since it returns either a
1 or 0. It is important that it be sent as a part of the same string as the command that causes a
flash update. As an example, sending CAL:SAVE 12/31/2005;:*opc? or *opc?;:CAL:SAVE
12/31/2005 are valid command strings. Sensing the commands separately will not verify that the
previous command is complete. Figure 3-2 is a program written in C, incorporating these techniques.
Failure to provide an adequate delay can result in:
• Commands that are not processed,
• The following command may be received in error, causing an error in the transmission,
• Unit lock-up requiring power cycling of the unit. If working via the GPIB bus, sending
Interface Clear and Device Clear followed by *RST will unlock the unit.
BHK-MG (OPR) 032816 3-19
#include <formatio.h>
#include <utility.h>
#include <gpib.h>
#include <ansi_c.h>
/*Overhead for the use of a NATIONAL INSTRUMENTS gpib interface */
int unit_desc; // handle for the national instruments controller
int GPIbus=0; // GPIB card 0
int adr=6; // Power Supply address
char status_byte; // status byte from the power supply
#define MAV 0x10 /* bit 4 of the status byte is the Message AVailable bit by 488.2 specification */
/* Function Send_with_wait
INPUT: string to be sent to power supply
Description: adds the *OPC? query and performs serial polls to wait for the command to be completed.
*/
int Send_with_wait(char *command);
char snd[501]; // data to be sent to the power supply
char rcv [10]; // data from power supply
int j;
sprintf(snd,”%s;:*OPC?,command); // Add *OPC? to the command
// so there is a response from the
// power supply
Send(GPIbus, adr, snd, strlen(snd), 2); // Send the data to the power supply
for (j=0;j<500;j++)( // loop until ready (5 seconds max)
Delay(.05); // Wait for command to complete
ibrsp(unit_desc,&status_byte); // get status byte
if ((status_byte& 0x10) ==0x10) break;) // by looking for data in string
Receive (GPIbus, adr, rev, rev_buf_size,10); // so the error queue will not receive a 410 error
}
main( // test code to show operation of function.
unit_desc=ibdev(GPIbus,adr,adr/256,T100ms,1,0x40a);Delay(.005);
Send (GPIbus,adr,”VOLT 10;curr .01”,sizeof(“VOLT 10;curr .01”),NLEND;
Send_with_wait(“*SAV 10”);
}
3.4 RS232-C OPERATION
3-20 BHK-MG (OPR) 032816
FIGURE 3-2. PROGRAMMING EXAMPLE TO VERIFY PREVIOUS COMMAND HAS COMPLETED
The BHK-MG may be operated via an RS232-C terminal, or from a PC using a terminal emulation program. The default settings are as fo llows:
• Baud rate: 9600
• Parity: None
•Data Bits8
• Stop Bits 1
• Echo ON
•XON OFF
To change baud rate refer to PAR’s. B.73 and B.74. To select prompt refer to PAR’s. B.79 and
B.80. To select echo refer to PAR’s. B.75 and B.76. To select XON/XOFF, refer to PAR’s. B.77,
B.78.
3.4.1 SETTING RS 232 BAUD RATE
When the power supply is in local mode, command entry status , press MENU key until LCD
displays BAUD RATE =. The top line of the LCD indicates the current RS 232 baud rate (default
= 9600). Use and keys to scroll through the available baud rate settings (19200, 9600,
4800 or 2400). Press ENTER to accept new setting (new baud rate is effective immediately), or
CLEAR to exit without changing setting.
3.4.2 SERIAL INTERFACE
The serial interface behaves like the GPIB interface in that the command is parsed after receiving a control character of either a Line Feed or Carriage Retur n. The serial interfa ce support s six
special control characters. The three special control characters are:
Backspace (08
) Causes the last character in the input buffer to be removed from the
H
input buffer queue.
Carriage Return (0D
Line Feed (0A
H
) Causes the input buffer to be parsed by the BHK-MG.
H
) Causes the inp u t bu ffer to be parsed by the BHK-MG.
3.4.3 RS 232 IMPLEMENTATION
The following paragraphs are provided to help the user understand how the RS 232 serial interface is implemented in the BHK-MG. Since the RS 232 protocol does not use a parity bit, the
echo mode is the default method used to ensure reliable communication between the command
originator (computer) and the BHK-MG power supply, thus avoiding a more complex “handshake” protocol.
When the BHK-MG is in the RS 232 echo mode it returns all data sent to the host controller. The
BHK-MG provides two additional options that allow handshake communication: the Prompt
method and the XON XOFF method. In stand ar d e cho mode the contro ller mu st ver ify th at ea ch
character is echoed back by the BHK-MG. As shown in Figure 3-3, there are times when the
BHK-MG does not echo back the character from the controller, requiring that the controller
resend the character. By using the handshake options (prompt and XON XOFF) the host controller can ensure that serial data interrupts occurring after parsing of the incoming message do
not result in lost data.
Figure 3-3 illustrates the default echo mode, the prompt method and the XON XOFF method
described in the following paragraphs.
BHK-MG (OPR) 032816 3-21
FIGURE 3-3. RS 232 IMPLEMENTATION
Only three control characters (characters between 00H and 1FH) are acknowledged by the
power supply:
• Carriage Return (CR, 0D
• Line Feed (LF, 0A
• Back Space (BS, 08
BS deletes the last character entered, with the exception of CR or LF characters. Either the CR
or LF character acts as the line terminator, initiating parsing of the ASCII data sent to the BHKMG by the command originator. When the line is parsed, the BHK-MG sends the line terminator
sequence CR LF to the command originator.
All non-control characters are sent via the serial port of the command originator. The control
character BS is echoed as BS Space BS. Only the first control character is returned in response
to either a CR LF or LF CR character sequence (see Figure 3-3).
3.4.3.1 ECHO MODE
In echo mode each byte (character) is echoed back to the sender where it is verified as the
same character that was just sent.
All non-control characters are sent via the serial port of the command originator. The control
character BS is echoed as BS Space BS. Only the first control character is returned in response
to either a CR LF or LF CR character sequence (see Figure 3-3).
3.4.3.2 PROMPT METHOD
)
H
)
H
)
H
The command originator sends a message line (command) to the BHK-MG and waits until the
prompt sequence CR LF > (3E
CR LF > to the command originator indicating the power supply is ready to receive the next
command and data will not be lost.
3.4.3.3 XON XOFF METHOD
The XON XOFF method allows the BHK-MG to control when the command originator is allowed
to send data. The command originator can only send data af ter the XON (transmission on) character (011
) has been received; the command originator stops sending data after receiving the
H
XOFF (transmission off) character (013
sending additional data.
3-22 BHK-MG (OPR) 032816
, 6210) is received. The BHK-MG sends the prompt sequence
H
), and waits until the XON character is received before
H
Control characters, either CR or LF, are returned as XOFF CR if echo mode is on, and as XOFF
if echo mode is off. XOFF stops data from the command originator and the BHK-MG returns the
normal sequence of CR LF (if echo mode is enabled).
3.4.4 ISOLATING RS 232 COMMUNICATION PROBLEMS
A Loop Back test can be run from the front panel to aid in isolating RS 232 communication problems. The unit is designed to pass the test only with the Loop Back test connector (part of Kit
219-0436, see Table 1-5) installed.
1. With the power supply in local mode, command entry s tatus , pres s MENU key until LCD
reads LOOP BACK TEST UNTESTED 1=RUN.
2. Press the 1 key to run the test with the Loop Back Test connector NOT installed and verify
the LCD reads FAILED. If the LCD reads PASSED, the power supply is defective and
requires repair.
3. Install the loop back test connector into RS 232 port and press the 1 key to rerun the test. If
the LCD reads PASSED, the power supply is operating properly. If the LCD reads FAILED,
the unit requires repair.
4. To test the integrity of the cable assembly connecting the power supply RS 232 port to the
computer, remove the Loop Back test connector from the power supply RS 232 port and
connect the cable in its place. With the DB9 adapter installed on the opposite end of the
cable, connect a short jumper wire between pins 2 and 3 of the adapter connector and
repeat the test of (3) above. If the LCD display re ads FAILED, the cord is either the improper
type (not null modem) or is defective. If the LCD display reads PASSED, the cable is correct;
remove the jumper and reconnect the cable to the computer.
If each of the above steps is completed successfully, the problem lies in the computer hardware and/or software. Refer to the Product Support area of the Kepco website for additional
information regarding RS 232 communications problems: www.kepcopower.com/support.
3.5 SCPI PROGRAMMING
SCPI (Standard Commands for Programmable Instruments) is a programming language conforming to the protocols and standards established by IEEE 488.2 (reference document
ANSI/IEEE Std 488.2, IEEE Standard Codes, Formats, Protocols , and Common Commands). SCPI commands are sent to the BHK-MG Power Supply as ASCII output strings within the selected programming language (PASCAL, BASIC, etc.) in accordance with the manufacturer’s
requirements for the particular GPIB controller card used.
Different programming languages (e.g., BASIC, C, PASCAL, etc.) have different ways of representing data that is to be put on the IEEE 488 bus. It is up to the programmer to determine how
to output the character sequence required for the programmi ng language used. Address inf ormation (GPIB address) must be included before the command sequence. (See PAR.3.3.3 to
establish the BHK-MG Power Supply GPIB address.)
3.5.1 SCPI MESSAGES
There are two kinds of SCPI messages: program messages from controller to power supply,
and response messages from the power supply to the controller. Program messages consist of
one or more properly formatted commands/queries and instruct the power supply to perform an
action; the controller may send a program message at any time. Response messages consist of
BHK-MG (OPR) 032816 3-23
formatted data; the data can contain information regarding operating parameters, power supply
state, status, or error conditions.
3.5.2 COMMON COMMANDS/QUERIES
Common commands and queries are defined by the IEEE 488.2 standard to perform overall
power supply functions (such as ide ntification, status, or synchronization) unrelated to specific
power supply operation (such as setting voltage/current). Common commands and queries are
preceded by an asterisk (*) and are defined and explained in Appendix A (see Table 4-4). Refer
also to syntax considerations (PARs 3.4.3 through 3.4.6).
3.5.3 SCPI SUBSYSTEM COMMAND/QUERY STRUCTURE
Subsystem commands/queries ar e related to specific power supply functions (such as s etting
output voltage, current limit, etc.) Figure 3-5 is a tree diagram illustrating the structure of SCPI
subsystem commands used in the BHK-MG Pow er Supply with the “root” at the left side, and
specific commands forming the branches. The following paragraphs introduce the subsystems;
subsystem commands are defined and explained in Appendix B.
3.5.3.1 ABORT SUBSYSTEM
This subsystem allows pending trigger levels to be cancelled.
3.5.3.2 INITIATE SUBSYSTEM
This subsystem enables the trigger system. When a trigger is enabled, the triggering action will
occur upon receipt of a GPIB <GET>, *TRG or TRIGger command. If a trigger circuit is not
enabled, all trigger commands are ignored.
3.5.3.3 LIST SUBSYSTEM
The LIST subsystem is represente d by 250 memory locations (groups of settings) which are
stored in the volatile memory. Each setting contains values for: Current, Voltage, and Time. The
range for the first two values is the maximum available range for the specific power supply. The
Time setting is between 0.01 and 655.3 5 seconds.
3.5.3.4 MEASURE SUBSYSTEM
This query subsystem returns the voltage and current measured at the power supply's output
terminals.
3.5.3.5 OUTPUT SUBSYSTEM
This subsystem controls the power supply's voltage and current outputs
3.5.3.6 INSTRUMENT SUBSYSTEM
This subsystem controls the power supply's voltage and current outputs and allows compatibility
with other vendor’s products
3-24 BHK-MG (OPR) 032816
3.5.3.7 STATUS SUBSYSTEM
This subsystem programs the power supply status register. The power supply has two groups of
status registers: Operation and Questionable. Each group consist s of thr ee register s: Cond ition,
Enable, and Event.
3.5.3.8 SYSTEM SUBSYSTEM
This subsystem controls the RS 232 port, as well as system errors, passwords, security, language, beep, version and keyboard lockout
3.5.3.9 TRIGGER SUBSYSTEM
This subsystem controls the remote triggering of the power supply.
3.5.3.10 [SOURCE:]VOLTAGE AND [SOURCE:]CURRENT SUBSYSTEMS
These subsystems program the output voltage and current of the power supply.
3.5.3.11 CALIBRATE SUBSYSTEM
The BHK-MG series of power supplies suppor t sof tware calibration. A full calibration consist of a
voltage calibration and a current calibration. Both voltage and current calibrations consist of a
zero and a full scale calibration. There are two ways to perform the calibration: locally using the
front panel keys, or remotely sending command s through the GPIB bus. These two ways cannot
be combined.
In order to enter the calibration mode the correct calibration access code (password) must be
entered. If the password has been forgotten call the factory and a secret password (which has
been assigned to your power supply) will be provided. During the calibration, new calibration
data is computed which is than stored in the non volatile memory.
The equipment required for calibration is specified in PAR. 4.2.
Because the voltage measured will be used as reference for calibration, the DVM itself must be
calibrated accurately. During voltage calibration, the voltage, overvoltage and voltage readback
are calibrated and during current calibration the current, overcurrent and current readback are
calibrated. The normal procedure is to calibrate voltage first and then current. However, you do
not have to do a complete calibra tion each time . If required, you may calibrate only the voltage
or the current and then proceed to saving the calibration results. For voltage calibra tion all loads
must be disconnected and the sense terminals connected to the corresponding output terminals. The digital voltmeter will be connected to the output of the power supply. For current calibration after disconnecting all loads an appropriate shunt resistor will be connected across
output terminals and the digital voltmeter will be connected across the sense terminals of the
shunt resistor.
3.5.4 PROGRAM MESSAGE STRUCTURE
SCPI program messages (comma nds from controller to power supp ly) consist of one or more
message units ending in a message terminator (required by Kepco power modules). The message
terminator is not part of the syntax; it is defined by the way your programming language indicates the end of a line (“newline” character). The message unit is a keyword consisting of a single command or query word followed by a message terminator (e.g., CURR?<newline> or
TRIG<end-of-line>). The message unit may include a data parameter after the keyword sepa-
BHK-MG (OPR) 032816 3-25
rated by a space; the parameter is usually numeric (e.g., CURR 5<newline>), but may also be a
string (e.g., OUTP ON<newline>). Figure 3-4 illustrates the message structure, showing how
message units are combined. The following subparagraphs explain each component of the
message structure.
NOTE: An alternative to usin g the mess age stru cture for multiple messages defined in the fol-
lowing paragraphs is to send each command as a sep arate line. In this case each command must use the full syntax shown in Appendix B.
3.5.4.1 KEYWORD
Keywords are instructions recognized by a decoder within the BHK-MG, referred to as a
“parser.” Each keyword describes a command function; all keywords used by the BHK-MG are
listed in Figure 4-1.
Each keyword has a long form and a short form. For the long form the word is spelled out completely (e.g. STATUS, OUTPUT, VOLTAGE, and TRIGGER are long form keywords). For the
short form only the first three or four letters of the long form are used (e.g., STAT, VOLT, OUTP,
and TRIG). The rules governing short form keywords are presented in Table 4-5.
TABLE 3-9. RULES GOVERNING SHORTFORM KEYWORDS
IF NUMBER OF LETTERS IN
LONGFORM KEYWORD IS:
4 OR FEWER (DOES NOT MATTER) ALL LONG FORM LETTERS MODE
5 OR MORE
AND FOURTH LETTER
IS A VOWEL?
You must use the rules above when using keywords. Using an arbitrary short form such as
ENABL for ENAB (ENABLE) or IMME for IMM (IMMEDIATE) will result in an error. Regardless
of which form chosen, you must include all the letters required by that form.
To identify the short form and long form in this manual, keywords are written in upper case letters to represent the short form, followed by lower case letters indicating the long form (e.g.,
IMMediate, EVENt, and OUTPut). The parser, however, is not sensitive to case (e.g., outp,
OutP, OUTPUt, ouTPut, or OUTp are all valid).
3.5.4.2 KEYWORD SEPARATOR
If a command has two or more keywords, adjacent keywords must be separated by a colon (:)
which acts as the keyword separator (e.g., CURR:LEV:TRIG). The colon can also act as a root
specifier (paragraph 3.4.4.7).
3.5.4.3 QUERY INDICATOR
NO
YES
THEN SHORT FORM
CONSISTS OF:
THE FIRST FOUR
LONG FORM LETTERS
THE FIRST THREE
LONG FORM LETTERS
EXAMPLES
MEASure, OUTPut, EVENt
LEVel, IMMediate, ERRor
The question mark (?) following a keyword is a query indicator. This changes the command into
a query. If there is more than one keyword in the command, the query indicator follows the last
keyword. (e.g., VOLT? and MEAS:CURR?).
3-26 BHK-MG (OPR) 032816
FIGURE 3-4. MESSAGE STRUCTURE
CURR:LEV 3.5;:OUTP ON;:CURR?<NL>
MESSAGE TERMINATOR
KEYWORD
QUERY INDICATOR
ROOT SPECIFIER
MESSAGE UNIT SEPARATOR
DATA
KEYWORD
KEYWORD
KEYWORD SEPARATOR
KEYWORD
MESSAGE UNIT SEPARATOR
DATA
MESSAGE UNIT
DATA SEPARATOR
DATA SEPARATOR
ROOT SPECIFIER
3.5.4.4 DATA
Some commands require data to accompany the keyword either in the form of a numeric value
or character string. Data always follows the last keyword of a command or query (e.g.,
VOLT:LEV:TRIG 14 or SOUR:VOLT? MAX
3.5.4.5 DATA SEPARATOR
Data must be separated from the last keyword by a space (e.g., VOLT:LEV:TRIG 14 or
SOUR:VOLT? MAX
3.5.4.6 MESSAGE UNIT SEPARATOR
When two or more message units are combined in a program messag e, they must be sep arated
by a semicolon (;) (e.g., VOLT 15;MEAS:VOLT? and CURR 12; CURR:TRIG 12.5).
BHK-MG (OPR) 032816 3-27
ABORt subsystem
ABORt
INITiate subsystem
INITiate
[:IMMediate]
:CONTinuous bool
:CONTinuous?
CALibrate subsystem
CALibrate
:COPY
:DUMP
:CURRent
:LEVel (MIN | MAX | MAG | PROT)
[:DATA] val
:PASS
“RESTore
:SAVE
:VOLTage
:LEVel (MIN | MAX | PROT)
[:DATA] val
:ZERO
MEASure subsystem
MEASure
[:SCALar]:CURRent[:DC]?
[:SCALar]:[VOLTage][:DC]?
INSTRument subsystem
INSTrument
:STATe?
:STATe (ON | OFF)
OUTPut subsystem
OUTPut
[:STATe] ON or OFF
[:STATe]?
DISPlay subsystem
DISPlay
:CONTrast 0.0 to 0.9
:CONTrast ?
:MODE
:MODE?
:TEXT
:TEXT?
ROOT : (colon)
SYSTem subsystem
SYSTem
:BEEP
:COMM:GPIB:ADDR val
:COMM:GPIB:ADDR?
:COMM:SER
:BAUD val
:BAUD?
:ECHO
:ECHO? ON, OFF
:PACE
:PACE? NONE, XON
:PROMpt
:PROMpt? ON, OFF
:ERRor
?
:CODE?
:ALL?
:KLOCk <boolean>
:KLOCk?
:PASSword
[:CENAble] (code)
:CDISenable (code)
:NEW (OLD | NEW)
:STATe?
:SECUrity
:IMMediate
:VERSion?
LIST subsystem
LIST
:CLE
:COUNt val
:COUNt?
:COUNt:SKIP val
:COUNt:SKIP?
:CURRent
[:LEVel] val
[:LEVel]?
: :POINt?
:DWELl val
:DWELl?
:DIR val
:DIR?
:DWELl?
: :POINt?
:QUERy val
:QUERy?
:VOLTage
[:LEVel] val
[:LEVel]?
: :POINt?
[SOURce:] subsystem
[SOURce:]
CURRent
[:LEVel]
[:IMMediate]
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:TRIGgered
[:AMPLitude] val
[:AMPLitude]?
:LIMit
[:HIGH] val
[:HIGH]? MIN, MAX
:MODE (LIST | FIX)
:MODE? LIST, FIX
:PROTection val
:PROTection?
:RANGe (UPPer | LOWer)
:RANGe?
VOLTage
[:LEVel]
[:IMMediate]
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:TRIGgered
[:AMPLitude] val
[:AMPLitude]?
:LIMit
[:HIGH] val
[:HIGH]? MIN, MAX
:MODE (LIST | FIX)
:MODE? LIST, FIX
:PROTection val
:PROTection?
FUNCtion
:MODE?
STATus subsystem
STATus
:OPERation
:CONDition?
:ENABle val
:ENABle?
[:EVENt]?
:PRESet
:QUEStionable
:CONDition?
:ENABle val
:ENABle?
[:EVENt]?
TRIGGER subsystem
TRIGger
:SOURce
See PAR. 3.3.6.2 and Figure 3-2 for
special programming considerations.
FIGURE 3-5. TREE DIAGRAM OF SCPI COMMANDS USED WITH BHK-MG POWER SUPPLY
3-28 BHK-MG (OPR) 032816
3.5.4.7 ROOT SPECIFIER
The root specifier is a colon (:) that precedes the first keyword of a program message. This
places the parser at the root (top left, Figure 4-3) of the command tree. Note the difference
between using the colon as a keyword separator and a root specifier in the following examples:
VOLT:LEV:IMM 16 Both colons are keyword separators.
:CURR:LEV:IMM 4 The first colon is the root specifier, the other two are keyword separators.
VOLT:LEV 6;:CURR:LEV 15 The second colon is the root specifier, the first and third are key-
word separators
:INIT ON;:TRIG;:MEAS:CURR?;VOLT? The first three colons are root specifiers.
3.5.4.8 MESSAGE TERMINATOR
The message terminator defines the end of a message. One message terminator is permitted:
• new line (<NL>), ASCII 10 (decimal) or 0A (hex)
NOTE: Kepco power supplies require a message terminator at the en d of each program mes-
sage. The examples shown in this manual assume a message terminator will be added
at the end of each message. Where a message terminator is shown it is represented
as <NL> regardless of the actual terminator character.
3.5.5 UNDERSTANDING THE COMMAND STRUCTURE
Understanding the command structure requires an understanding of the subsystem command
tree illustrated in Figure 3-5. The “root” is located at the top left corner of the diagram. The
parser goes to the root if:
• a message terminator is recognized by the parser
• a root specifier is recognized by the parser
Optional keywords are enclosed in brackets [ ] for identification; optional keywords can be omitted and the power supply will respond as if they were included in the message. The root level
keyword [SOURce] is an optional keyword. Starting at the root, there are various branches or
paths corresponding to the subsystems. The root keywords for the BHK-MG Power Supply are
:ABORt, :CALibrate, :DISPlay, :INITiate, :LIST, :MEASure, :OUTPut, [:SOURce], :STATus,
:SYSTem and :TRIGger. Because the [SOURce] keyword is option al, the p a rser moves the p a th
to the next level, so that VOLTage, CURRent, and FUNCtion commands are at the root level.
Each time the parser encounters a keyword separator, the parser moves to the next indented
level of the tree diagram. As an example, the STATus branch is a root level branch that has
three sub-branches: OPERation, PRESet, and QUEStionable. The following illustrates how
SCPI code is interpreted by the parser:
STAT:PRES<NL>
The parser returns to the root due to the message terminator.
STAT:OPER?;PRES<NL>
The parser moves one level in from STAT. The next command is expected at the level defined
by the colon in front of OPER?. Thus you can combine the following message units
STAT:OPER? and STAT:PRES;
BHK-MG (OPR) 032816 3-29
STAT:OPER:COND?;ENAB 16<NL>
After the OPER:COND? message unit, the parser moves in one level from OPER, allowing the
abbreviated notation for STAT:OPER:ENAB.
3.5.6 PROGRAM MESSAGE SYNTAX SUMMARY
• Common commands begin with an asterisk (*).
• Queries end with a question mark (?).
• Program messages consist of a root keyword and, in some cases, one or more message units separated by a colon (:) followed by a message terminator. Several message units of a program message may be separated by a semicolon (;) without
repeating the root keyword.
• If a program message has more than one message unit, then a colon (:) must precede
the next keyword in order to set the parser back to the root (otherwise the next keywor d
will be taken as a subunit of the previous message unit).
e.g., the command meas:volt?;curr? will read output voltage and output current
since both volt? and curr? are interpreted as subunits of the meas command.
• Several commands may be sent as one message; a line feed terminates the message.
Commands sent together are separated by a semicolon (;). The first command in a
message starts at the root, therefor a colon (:) at the beginning is not mandatory.
e.g., the command meas:volt?;:curr? will read output voltage and programmed
current since the colon preceding curr? indicates that curr? is not part of the meas
command and starts at the root.
• UPPER case letters in mnemonics are mandatory (short form). Lower case letters may
either be omitted, or must be specified completely (long form)
e.g., INSTrument (long form) has the same effect as INST (short form).
• Commands/queries may be given in upper/lower case (long form)
e.g., SoUrCe is allowed.
• Text shown between brackets [ ] is optional.
e.g., :[SOUR]VOLT:[LEV] TRIG has the same effect as :VOLT TRIG
3.5.7 SCPI PROGRAM EXAMPLES
Refer to Appendix B, Figures B-1 through B-7 for examples illustrating the use of SCPI commands.
Figure 3-6 is an example of a progr am using SCPI commands to program the BHK-MG Power
Supply. The program illustrated is for a configuration using an IBM PC or compatible with a
National Instruments GPIB interface card. (It will be necessary to consult the manufacturer’s
data to achieve comparable functions with an interface card from a different manufacturer.) This
program sets output voltage (Voltage mode) or voltage limit (Current mode) to 5V, and current
limit (Voltage mode) or output current (Current mode) to 1A, then reads the measured (actual)
voltage and current, then prints the measurements.
3-30 BHK-MG (OPR) 032816
/**************************************************************************/
/* Sample Program For KEPCO power supply, using National Instruments */
/* GPIB interface card and IBM PC or compatible computer */
/**************************************************************************/
#include <stdio.h>
#include "decl.h"
char rd_str[80]; // Input buffer
char dat_str[80]; // Output buffer
int bd,adr;
main() {
adr = ibfind("DEV6"); // Open DEV6 (defined by IBCONF)
bd = ibfind ("GPIB0"); // Open GPIB card
ibsic (bd); // Send Interface Clear
ibsre(bd,1); // Set remote line true
strcpy(dat_str,"VOLT 5;CURR 1"); // Define a set command
strcat(dat_str,"\r\n"); // Append delimiter
ibwrt(adr,dat_str,strlen(dat_str)); // Send string to power supply
strcpy(dat_str,"MEAS:VOLT?;CURR?"); // Define a measure command
strcat(dat_str,"\r\n"); // Append delimiter
ibwrt(adr,dat_str,strlen(dat_str)); // Send string to power supply
strset(rd_str,'\0'); // Clear input buffer
ibrd(adr,rd_str,64); // Read result of measure
printf("received : %s\n",rd_str); // Print voltage and current
}
FIGURE 3-6. TYPICAL EXAMPLE OF BHK-MG POWER SUPPLY PROGRAM USING SCPI COMMANDS
3.6 REMOTE PROGRAMMING USING ANALOG PROGRAMMING TERMINALS
The BHK-MG power supply is designed with separate, but similar, circuits for analog voltage
programming (Figure 3-7) and analog current programming (Figure 3-8). The voltage programming circuit is used for programming output voltage if the unit is in voltage mode, or voltage limit
if the unit is in current mode. Similarly, the current programming circuit programs output current
in current mode, and current limit in voltage mode.
For each circuit, the digital programmi ng section provides a voltage (DP (V) for voltage, DP (C)
for current), between zero and -10V d-c, applied to the inpu t of a su mming and co rrection a mplifier. This amplifier drive s, in turn, the volt age e rror amplifier an d the p ass element to produce the
output. Each circuit also includes an uncommitted amplifier which can be configured to be
summed with the output of the digital programming section at the input of the summing and cor-
BHK-MG (OPR) 032816 3-31
rection amplifier. Configuration of the uncommitted amplifiers is accomplished at the ANALOG
PROGRAMMING TERMINALS at the rear panel: VOLTAGE PROG. terminal strip TB2 for voltage, CURRENT PROG. terminal strip TB3 for current.
FIGURE 3-7. ANALOG VOLTAGE PROGRAMMING, SIMPLIFIED DIAGRAM
FIGURE 3-8. ANALOG CURRENT PROGRAMMING, SIMPLIFIED DIAGRAM
3-32 BHK-MG (OPR) 032816
If digital programming is at zero, analog programming requires a voltage between zero and
10 Eout
dp
–
10
Eomax
----------------------
V–
10 I out
dp
–
10
Iomax
--------------------
V–
WARNING
–10V d-c to be applied to terminal 9 (TB2 for voltage, TB3 for current). If digital programming is combined with analog programming, the voltage range for the signal applied to terminal 9 is:
Voltage programming: TB2-9: 0 to
Current programming: TB3-9: 0 to
where:
Eout
Iout
= digitally programmed output voltage/voltage limit
dp
= digitally programmed output current/current limit
dp
The uncommitted amplifiers can be configured to produce the require d voltage fr om a number of
analog sources. Some basic analog configurations are presented in the following paragraphs:
• External resistance
• Low impedance voltage source
• Grounded voltage source
• High impedance voltage source
• Current source
Different analog sources can be used simultaneously; e.g., resistance can be sued to control
voltage programming while a grounded voltage source controls current programming. Analog
programming can also be combined with digital programming (either locally via the keypad or
remotely via the GPIB bus) since the two programming methods are summed together. For
example, for the BHK 500-0.4MG Power Supply, if the output is programmed digitally to 200V,
and an analog signal which would produce a 100V output is applied to the uncommitted amplified, the output would go to 300V (assuming the value of the load and the programmed value of
output current allow the power supply to remain in voltage mode).
NOTE: It is important to remember that BOTH voltage and current channels must be pro-
grammed (e.g., if analog programming of voltage mode is used, the current limit must
be programmed by either analog or digital programming).
The availability of the two uncommitted amplifiers, ±10V d-c reference voltages and the two
summing amplifiers, means that many configurations are possible for analog control of the
power supply.
3.6.1 ANALOG PROGRAMMING WARNINGS AND CAUTIONS
THE POWER SUPPLY PRODUCES DANGEROUS VOLTAGES WHICH CAN BE LETHAL.
ALWAYS OBSERVE THE FOLLOWING PRECAUTIONS.
a. Always connect the chassis of the power supply to a good AC ground (earth) con-
nected to OUTPUT TERMINALS terminal strip TB1, terminal 4.
NOTE: All connections must be tight, whether at the terminal strips of the power supply or at
external equipment.
BHK-MG (OPR) 032816 3-33
b. Use high voltage rated cables (at least 3kV) for all connections, even for programming
WARNING
WARNING
connections. Where required use twisted pair cable or shielded single or pair cable
(shield to chassis), rated for high voltage.
c. Even though the BHK-MG Power Supply will discharge the output capacitor at turn-off,
verify that the output is safe before making any attempt to connect or disconnect the
load.
d. Verify that the input circuit breaker is off and remove the line cord before connecting or
disconnecting the load or other external components to analog programming terminals.
e. If possible, connect one side of the output to ground (either side may be grounded).
The power supply can also operate with the output “floating” with respect to ground.
The following warnings and cautions apply to the output terminals:
• If the external equipment (e.g., Digital Voltmeter) has floating inputs and the power supply is operating with +OUT termina l connected to ground, connect the LOW input of the
external equipment to +OUT terminal of the power supply.
• If the external equipment (e.g., Digital Voltmeter) has floating inputs and the power supply is working with –OUT terminal connected to ground, connect the LOW input of the
external equipment to –OUT terminal of the power supply.
• If the power supply outputs should stay isolated from ground, any external equipment
connected to the output terminal should be connected to a-c source power using an isolating transformer, or should have floating inputs.
NOTE:Any isolating transformer used for connecting test equipment to a-c source power
should have the isolation rated to a value higher than the maximum output voltage of the power supply.
The following warnings and caut ions apply to the analog programming terminals because the
analog control circuitry operates at the +OUTPUT potential and the common of the analog control circuitry is connected to the +OUT terminal (TB1) through the sensing resistor (Rs) of the
power supply.
• If the power supply is operating with +OUT terminal connected to ground, do not connect
grounded inputs or outputs of any external equipment to power supply analog programming terminals. If this situation is un avoidable, connect the external equipment to a-c
source power using an isolating transformer. For external equipment with grounded output only, use the uncommitted amplifier of the power supply in differential configuration.
• If the power supply is operating with –OUT terminal connected to ground, the external
programming source must be isolated up to the maximum output voltage plus 1KV. The
programming source must be either battery powered or powered through an isolation
transformer and feature “fully insulate d co nt ro ls and cha ssis .”
3-34 BHK-MG (OPR) 032816
• If the power supply must operate isolate d fro m ground ( floating ), any exter nal equipme nt
connected to the ANALOG PROGRAMING TERM INALS must also be isolated (batt ery
operated or connected to a-c source power using an isolating transformer).
Safety Messages
The BHK-MG can be controlled by digital and/or analog inpu t s. When OUTPUT is set to o f f from
the keypad or the GPIB, an analog input will still produce an output from the BHK-MG which will
be indicated on the LCD. If the analog input is causing more than 8Vd-c to appear at the output
terminals, or if current being supplied to the load exceeds 1mA, the unit will beep and enter a
controlled shutdown for safety purposes unless the override jumper has been installed (see
Table 2-9).
3.6.2 PROGRAMMING WITH EXTERNAL RESISTANCE
Figures 3-9 and 3-10 are simplified diagrams of the BHK-MG showing the jumper configuration
and external connections required for analog programming using an external resistance. Figures 3-9 shows programming of either output voltage when the unit is in voltage mode, or voltage limit when the unit is in current mode. Figure 3-10 is a similar diagram for programming
either output current when the u nit is in cu rr en t mode, or current limit when the unit is in v oltage
mode.
FIGURE 3-9. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE)
OR VOLTAGE LIMIT (CURRENT MODE) USING RESISTANCE
BHK-MG (OPR) 032816 3-35
FIGURE 3-10. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE)
OR CURRENT LIMIT (VOLTAGE MODE) USING RESISTANCE
For either voltage programming or current programming, the external resistor R
connected
EXT
across terminals 6 and 8 of VOLTAGE PROG terminal strip TB2 or CURRENT PROG. terminal
strip TB3 functions as a feedback resistor for the internal uncommitted amplifier dedicated to
voltage or current programming. This uncommitted amplifier is configured to amplify and invert
the +10V reference applied via terminals 4 and 6 of TB2 or TB3. The output of the uncommitted
amplifier is applied via terminals 8 and 9 of TB2 or TB3 to a summing ne two rk at the inpu t of the
summing and correction amplifier. For voltage programming, the other input to the summin g and
correction amplifier, DP (V), is from the voltage portion of the digital programming circuitry
(either from the keypad or the GPIB bus). For curren t program ming, the ot her input to the su mming and correction amplifier, DP (C), is from the current portion of the digital programming circuitry (either from the keypad or the GPIB bus).
TABLE 3-10. FEEDBACK RESISTOR AND CURRENT SENSING RESISTOR VALUES
RESISTOR SCALE BHK 500-0.4MG BHK 1000-0.2MG BHK 2000-0.1MB
Voltage Feedback Resistor R 500K* 1000K* 2000K*
Current Sensing Resistor Rs HIGH CURRENT 0.0025K* 0.005K* 0.010K*
LOW CURRENT 0.025K* 0.05K* 0.10K*
* All resistors are 1% tolerance.
3-36 BHK-MG (OPR) 032816
3.6.2.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-9) and the digitally programmed output
voltage at zero, varying the external resistor from 0 to 10K causes the output voltage of the
power supply to vary linearly fro m 0 to Eomax wit h a slope of (0.0001 x E omax) volts per ohm .
The following equation gives the output voltage as determined by external re sistance R
EXT
.
Eo = (–1) (10V) x (R
= (–1) (0.1 x R) x R
= –0.1R x R
where
R
= External resistance (K-ohms), variable from 0 to 10K ohms. This resistance can take
EXT
the form of a rheostat, a fixed resistor, or a group of resistors which are step-switched
by mechanical, electrical or electronic means (step-switching must be “make before
break”). Use only high quality r esistor(s) having a temperature coefficient of 20 parts
per million or better and a wattage rating of 0.5W minimum.
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
NOTE: Output voltage is referenced to +OUT and output current is negative le aving +OUT te r-
minal. This convention applies to voltage and current programming calculations of
PAR. 3.6.
3.6.2.2 CURRENT MODE
With the power supply in current mode (see Figure 3-10) and the digitally programmed output
voltage at zero, varying the external resistor from 0 to 10K causes the output current of the
power supply to vary linearly from 0 to Iomax with a slope of (0.0001 x Iomax) mA pe r ohm. The
following equation gives the output current as determined by external resistance R
EXT
/10K) x (–1) (10K/10K) x (–1) (R/10K)
EXT
EXT
(V d-c)
EXT
.
Io = [ (–1) (10V) x (R
= (–1) (0.1/ Rs) x R
= (–0.1/Rs) x R
/10K) x (–1) (1K/10K) x (–1) (1K/1K) ]/Rs
EXT
EXT
(mA d-c)
EXT
where
Rs = Internal shunt resistance (K-ohms), determined by Model (see Table 3-10).
(See above for definition of R
BHK-MG (OPR) 032816 3-37
EXT
.)
3.6.3 PROGRAMMING WITH EXTERNAL VOLTAGE USING A LOW IMPEDANCE VOLTAGE
SOURCE
Figures 3-11 through 3-14 are simplified diagrams of the BHK-MG showing the jumper configuration and external connections required for analog programming using a low impedance voltage source. Figure 3-11 shows an isolated voltage source, Figure 3-12 shows a grounded
voltage source for programming of either output voltage when the unit is in voltage mode, or
voltage limit when the unit is in current mode . Figures 3-13 (isolated voltage sou rce) and 3-14
(grounded voltage source) are similar diagrams for programming either output current when the
unit is in current mode, or current limit when the unit is in voltage mode.
FIGURE 3-11. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VO LTAGE LIMIT
(CURRENT MODE) USING ISOLATED (FLOATING) LOW IMPEDANCE VOLTAGE SOURCE (VS)
3-38 BHK-MG (OPR) 032816
FIGURE 3-12. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING GROUNDED LOW IMPEDANCE VOLTAGE SOURCE (VS)
BHK-MG (OPR) 032816 3-39
FIGURE 3-13. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT LIMIT
(VOLTAGE MODE) USING ISOLATED (FLOATING) LOW IMPEDANCE VOLTAGE SOURCE (VS)
3-40 BHK-MG (OPR) 032816
FIGURE 3-14. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT
LIMIT (VOLTAGE MODE) USING GROUNDED LOW IMPEDANCE VOLTAGE SOURCE (VS)
The external voltage source is applied to the input of the uncommitted amplifier which is configured either as an inverting repeater (Figures 3-11 and 3-13) for isolated voltage sources or a differential amplifier having a gain of –1 (Figures 3-12 and 3-14) for grounded voltage sources.
The positive voltage is applied to the inverting input of the uncommitted amplifier referenced to
internal signal ground. The voltage source impedance should be low compared to the 10K input
impedance into the programming terminals of the power supply.
Observe the following to avoid damage to the power supply. For isolated voltage sources
(Figures 3-11 and 3-13), the external voltage source output must be isolated from ground (floating output), or be powered from an a-c source that is isolated from ground to avoid short-circuiting the internal sensing resistor,. If neither of these options are practical, use the grounded
voltage source configurations shown in Figures 3-12 and 3-14.
BHK-MG (OPR) 032816 3-41
CAUTION
3.6.3.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-11 or 3-12) and the digitally programmed
output voltage at zero, varying the low impedance voltage source from 0 to +10V causes the
output voltage of the power supply to vary linearly from 0 to Eomax with a slope of (0.1 x
Eomax) volts per volt. The following equations give the output voltage as determined by a low
impedance voltage source V
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (–1) (V
EXT
= (–1) (0.1 x R) x V
= –0.1R x V
where
R = Internal feedback resistance (K-ohms), determined by Model (see Table 3-10).
V
= External low impedance voltage source. This so urce can be either a d-c source deliver-
EXT
ing a positive output voltage, or a function generator with an internal po sitive bias. If the
bias is not available from the function generator, use the digital programming feature of
the BHK-MG to provide proper bias to av oid clipping the waveform at the output of the
power supply.
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Eo = –(0.1 x R x V
.
EXT
) x (10K/10K) x (–1) (10K/10K) x (–1) (R/10K)
EXT
(V d-c)
EXT
) – EoutDP (V d-c)
EXT
where
Eout
= Output voltage programmed digitally (fr om either local keypad or remote GPIB bus)
DP
(See above for definitions of R and V
EXT
.)
3-42 BHK-MG (OPR) 032816
3.6.3.2 CURRENT MODE
With the power supply in current mode (see Figure 3-13 or 3-14) and the digitally programmed
output voltage at zero, varying the low impedance voltage source from 0 to +10V causes the
output current of the power supply to vary linearly from 0 to Iomax with a slope of (0.1 x Iomax)
mA per volt. The following equations give the output current as determined by the low impedance voltage source V
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Io = [ (–1) (V
= (–1) (0.1/ Rs) x V
= –(0.1/Rs) x V
where
Rs =Internal shunt resistance (K-ohms), determined by Model (see Table 3-10).
(See above for definition of V
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Io = –(0.1/Rs) x V
where
Iout
= Output current programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of Rs and V
.
EXT
) x (10K/10K) x (–1) (1K/10K) x (–1) (1K/1K) ]/Rs
EXT
EXT
EXT
(mA d-c)
EXT
(mA d-c)
.)
EXT
– IoutDP (mA d-c)
.)
EXT
3.6.4 PROGRAMMING WITH EXTERNAL VOLTAGE USING A HIGH IMPEDANCE, LOW LEVEL
(1V) VOLTAGE SOURCE
Figures 3-15 and 3-16 are simplified diagrams of the BHK-MG showing the jumper configur ation
and external connections required for analog programming using a high impedance, low level
(1V), voltage source. Figure 3-15 shows the configuration for programming of either output voltage when the unit is in voltage mode, or voltage limit when the unit is in current mode. Figure 316 is a similar diagrams for programming either output current when the unit is in current mode,
or current limit when the unit is in voltage mode
CAUTION
Observe the following to avoid damage to the power supply. The external voltage source
output must be isolated from ground (floating output), or be powered from an a-c source that is
isolated from ground to avoid short-ci rcuiting the internal sensing resistor.
BHK-MG (OPR) 032816 3-43
FIGURE 3-15. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING HIGH IMPEDANCE, LOW LEVEL (1V) VOLTAGE SOURCE (VS)
3-44 BHK-MG (OPR) 032816
FIGURE 3-16. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT
LIMIT (VOLTAGE MODE) USING HIGH IMPEDANCE, LOW LEVEL (1V) VOLTAGE SOURCE (VS)
The external voltage source is applied to the input of the uncommitted amplifier which is configured as a noninverting amplifier having a gain of 10.
BHK-MG (OPR) 032816 3-45
3.6.4.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-15) and the digitally programmed output
voltage at zero, varying the high impedance voltage source from 0 to –1V causes the output
voltage of the power supply to vary linearly from 0 to Eomax with a slope of (Eomax) volts per
volt. The following equations give the output voltage as determined by a high impedance voltage source V
EXT
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (V
) x (11.1K/1.1K) x (–1) (10K/10K) x (–1) (R/10K)
EXT
= –(R) x |V
where
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
V
= External low impedance voltage source. This so urce can be either a d-c source deliver-
EXT
ing a negative output voltage, or a function generator with an internal negative bias. If
the bias is not available from the function generator, use the digital programming feature of the BHK-MG to provide proper bias to avoid clipping the waveform at the output
of the power supply.
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Eo = –(R x |V
EXT
.
| (V d-c)
EXT
|) – EoutDP (V d-c)
where
Eout
= Output voltage programmed digitally (fr om either local keypad or remote GPIB bus)
DP
(See above for definitions of R and V
3.6.4.2 CURRENT MODE
With the power supply in current mode (see Figure 3-16) and the digitally programmed output
voltage at zero, varying the high impedance voltage source fr om 0 to –1V causes th e output current of the power supply to vary linearly from 0 to Iomax with a slope o f (Iomax) mA per volt. The
following equations give the output current as determined by the low impedance voltage source
V
.
EXT
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Io = [ (V
) x (11.1K/1.1K) x (–1 ) (1K/10K) x (–1) (1K/1K) ]/Rs
EXT
= –(1/Rs) x |V
where
Rs =Internal shunt resistance (kOhms), determined by Model (see Table 3-10).
(See above for definition of V
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Io = –(1/Rs) x |V
| (mA d-c)
EXT
.)
EXT
| – IoutDP (mA d-c)
EXT
EXT
.)
where
3-46 BHK-MG (OPR) 032816
Iout
= Output current programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of Rs and V
EXT
.)
3.6.5 PROGRAMMING WITH EXTERNAL CURRENT SOURCE (1 mA)
Figures 3-17 and 3-18 are simplified diagrams of the BHK-MG showing the jumper configur ation
and external connections required for analog programming using a current source (1mA). Figure 3-17 shows the configuration for programming of either output voltage when the unit is in
voltage mode, or voltage limit when the unit is in cur rent mode. Figure 3-18 is a similar diagrams
for programming either output current when the unit is in current mode, or current limit when the
unit is in voltage mode
CAUTION
Observe the following to avoid damage to the power supply. The ex ternal current source
output must be isolated from ground (floating output), or be powered from an a-c source that is
isolated from ground to avoid short-ci rcuiting the internal sensing resistor.
FIGURE 3-17. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING CURRENT SOURCE (1mA) (CS)
BHK-MG (OPR) 032816 3-47
FIGURE 3-18. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT
LIMIT (VOLTAGE MODE) USING CURRENT SOURCE (1mA) (CS)
The external current source is applied to the inverting input of the uncommitted amplifier which
is configured as a current-voltage converter.
Observe the following to avoid damage to the power supply. The ex ternal current source
output must be isolated from ground (floating output), or be powered from an a-c source that is
isolated from ground to avoid short-circuiting the internal sensing resistor.
3-48 BHK-MG (OPR) 032816
CAUTION
3.6.5.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-17) and the digitally programmed output
voltage at zero, varying the external current source from 0 to 1mA causes the output voltage of
the power supply to vary linearly from 0 to Eomax with a slope of (Eomax) volts per mA. The following equations give the output voltage as determined by the external current source I
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (–1)I
= –(R) x I
EXT
EXT
where
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
I
= External current source. This source can be either a d-c source or a function generator
EXT
with an internal bias delivering a constant current. If the bias is not available from the
function generator, use the digital programming feature of the BHK-MG to provide
proper bias to avoid clipping waveform at the output of the power supply.
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Eo = –(R x I
) – EoutDP (V d-c)
EXT
where
x (10K) x (–1) (10K/10K) x (–1) (R/10K)
(V d-c)
EXT
.
Eout
= Output voltage programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of R and V
3.6.5.2 CURRENT MODE
With the power supply in current mode (see Figure 3-18) and the digitally programmed output
voltage at zero, varying the external current source from 0 to 1mA causes the output current of
the power supply to vary linearly from 0 to Iomax with a slope of (I omax) mA per m A. The follo wing equations give the output current as determined by the external current source I
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Io = [ (–1) I
EXT
= –(1/Rs) x I
where
Rs =Internal shunt resistance (K-ohms), determined by Model (see Table 3-10).
(See above for definition of V
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Io = –(1/Rs) x I
where
Iout
= Output current programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of Rs and I
.)
EXT
x (10K) x (–1) (1K/10K) x (–1) (1K/1K) ]/Rs
(mA d-c)
EXT
.)
EXT
– IoutDP (mA d-c)
EXT
.)
EXT
EXT
.
BHK-MG (OPR) 032816 3-49
3.7 OPERATING MODES
This section describes the following operating modes for the BHK-MG power supply
• Slow/Fast Mode
• Series Operation
• Automatic Series Operation
• Master-Slave Series Operation
• Parallel Operation
• Automatic Parallel Operation
• Master-Slave Parallel Operation
3.7.1 SLOW/FAST MODE OF OPERATION
In slow mode of operation the internal output capacitor C
is connected across the sensing
OUT
terminals via TB1, terminal 7 (-OUT.C) and terminal 6 (-S). This effectively increases the main
feedback capacitance by adding the internal feedback capacitor for slow mode C
mode capacitor C
(see Figure 3-19). When internal output capacitor C
FF
is across the out-
OUT
. to the fast
FS
put, output noise is reduced, and, in voltage mode, the amplitude of transients caused by
dynamic load changes is also reduced. Th e disadvantage of slow mode is that programming
time is increased. Therefore, slow mode is recommended for voltage mode applications where
low noise and low amplitude recovery transients due to dynamic load changes are important.
In fast mode of operation the internal output capacitor is disconnected from the sensing terminals, by removing the link between TB1, terminal 7 (-OUT.C) and terminal 6 (-S). This also effe ctively reduces the main feedback capacitance by removing the internal capacitor for slow mode,
C
from the circuit. This configuration reduces the programming time in voltage mode and, in
FS
current mode, reduces the duration of transients caused by dynamic load changes; the disad vantage is that output noise is increased. Therefore, the fast mode of operation is recommended for voltage mode applications when a quick response to programming is important
(e.g., when the power supply is effectively operating as a power amplifier), and for current mod e
applications when quick recovery time at load changes is desired.
3-50 BHK-MG (OPR) 032816
FIGURE 3-19. SLOW MODE/FAST MODE OPERATION
If desired, an external output capacitor can also to be used; the following instructions apply
when using an external output capacitor:
a. Use a capacitor rated to more than the maximum output voltage of the power supply. If
a series combination of polarized type capacitors is used, potential equalizer resistors
in parallel with each capacitor should be installed and attention should be paid to the
polarity of the capacitors: the “plus” terminal of each capacitor is connected to the
“minus” terminal of the next capacitor, if present, or to +OUT terminal of the power supply (see Figure 3-19).
b. If precise control of the voltage across the external capacitor is desired, use remote
sensing: connect the sensing leads and power leads across the external outpu t cap a citor and connect the load to the external capacitor.
c. If the external capacitor has a value much smaller than internal output capacitor C
(see Table 1-2), then it is not necessary to connect the internal capacitor at the output
using the link between terminals TB1-6 and TB1-7. If the external capacitor is compar a-
BHK-MG (OPR) 032816 3-51
OUT
ble or larger than the internal C
WARNING
the output by installing the link between terminals TB1-6 and TB1-7, in order to
increase the main feedback capacitance.
Isolate all external circuitry connected to the ungrounded (“live”) output terminal of the power
supply; isolation should be rated to more than maximum output voltage.
3.7.2 SERIES OPERATION
Kepco BHK-MG power supplies can be series-connected to increase output voltage if the precautions outlined below are followed. Two basic series-connection methods are generally used:
automatic (PAR. 3.7.2.1) and master-slave (PAR. 3.7.2.2).
HANDLING HIGH VOLTAGE, LOW IMPEDANCE EQUIPMENT IS DANGEROUS, AND
POTENTIALLY LETHAL. OBSERVE ALL PRECAUTIONS LISTED IN PAR. 3.6.1., AS WELL
AS THE PRECAUTIONS LISTED BELOW.
a. Do not exceed the specified isolation voltage limit (see Table 1-2). If the isolation volt-
age might be exceeded, limit the excursion of one power supply output: e.g., if two
BHK 2000-0.1MG models are to be series-connected, the output of one must be
restricted to 0.5 kV (limiting the series combination to a maximum of 2.5kV), because
the isolation voltage for this model is 2kV + 0.5kV (see Ta ble 1-2).
, it is advisable to connect the internal C
OUT
CAUTION
OUT
across
b. Connect the chassis ground terminal, TB1-4, of all series-connected power supplies to
a good a-c ground (earth ground).
c. If necessary, the grounding network can be used for each one of the series-connected
power supplies within the limits of the maximum isolation voltage (see Table 1-2) of the
Model BHK-MG Series (refer to PAR. 2.7.5.3 for additional informati on re ga rding use of
the grounding network).
d. The series combination of BHK-MG power supplies can operate either isolated from
ground (floating) or with either of the two output terminals of the series combination
grounded. When analog programming is used, however, it is recommended that the
positive output terminal of the series comb ina tio n be gr ou nd ed to avo id po te nt ially hazardous conditions requiring the use of fully insulated external equipment (see precautions of PAR. 3.6.1).
If the negative output terminal is grounded, special precautions are required when using
external programming sources: THE PROGRAMMING SOURCE MUST BE ISOLATED AND
INSULATED for the sum of the voltages of the series combination. The programming source
must be either battery powered or powered through an isolation transformer and have “fully
insulated controls and chassis” features (see also PAR. 3.6.1).
e. Each BHK-MG power supply contains an internal, reverse-biased diode across the out-
put which protects the power supply by limiting the opposite polarity voltage at the output. This diode is rated for the nominal output voltage of each model (see Table 1-1).
When BHK-MG power supplies are series-connected, this diode will protect each sup-
3-52 BHK-MG (OPR) 032816
ply against a short circuit at the load, with one exception. The current rating of the
reverse-biased diode used on model BHK 2000-0.1MG is 0.2A. When this unit is connected in series with a model BHK 500-0.4MG, which has a maximum current rating of
0.4A, it is necessary to connect an external (reverse-biased) diode across the output of
the 2000V unit which is rated for 3kV reversed voltage and 0.4A direct current.
NOTE: The simplified schematic diagrams (Figures 3-20 through 3-22) illustrating the associ-
ated interconnections show the power supplies configured in either slow mode for units
operating in voltage mode or fast mode for units operating in current mode, however
other combinations are also possible. Due to the low current involved, the units are
shown using local sensing since the drop across the power leads is usually negligible
compared to the output voltage. However, when very precise control of output voltage
applied to the load is desired, remote sensing should be used. Contact Kepco Applications Engineering when special configurations are indicated.
3.7.2.1 AUTOMATIC SERIES OPERATION
This operating configuration (see Figure 3-20) is characterized by the fact that each power supply is independent and must be controlled (pr ogrammed) ind ividually, either remotely—via either
the GPIB bus or by analog means—or locally via the keypad. Practical considerations suggest
that the units operate in voltage mode - current limit, controlled from the local keypad. The output voltage and current of the series combination are giv en by the follo wing eq ua tio n s:
Eo = Eo
Io = Eo / R
+Eo
A
LOAD
B
where
Eo, Io are output values of the series combination (in Volts and milliamperes, respectively)
Eo
, EoB are the individual output voltages for two series-connected power supplies (in
A
Volts)
R
is the load value (in K-ohms).
LOAD
The maximum current delivered by the series combination is dictated by the power supply with
the lowest nominal current and correspondingly, the highest nominal output voltage. For the current limit to operate properly, set the desired value of current limit (for the series combination) at
the power supply with the highest nominal output volt age; set the cu rrent limit of the other power
supply to a larger value (1% larger or more).
RECOMMENDED PROCEDURE. The following steps are recommended to ensure the combination of power supplies configured for automatic series operation (power assembly) is prope rly
connected and set up properly.
1. With the units turned off, perform all external wiring (see Figure 3-20). If possible, use a
properly rated switch between the power supply and the load.
2. Apply power to the units:
a. If a load switch is used, open the switch. Set POWER switch of both units to up position
to turn power on.
b. If load switch is not used, set POWER switch of both units to up position to turn power
on, then press OUTPUT ON/OFF key once on eac h unit to disable the output.
3. Program Unit A as follows:
BHK-MG (OPR) 032816 3-53
NOTE: If using two different BHK models, e.g., 500-0.4MG and 1000-0.2MG, unit A must be
Vset Eo
EomaxA
EomaxA EomaxB+
--------------------------------------------------------------- -
=
the one with the lower current capacity: 1000-0.2MG
a. Program IsetA to the current limit for the power assembly.
b. Program VsetA to: (to nearest volt) where:
• Eo is the output voltage of the power assembly,
• EomaxA is the rated maximum output voltage for unit A (e.g. 500 for the BHK 500-
0.4MG),
• EomaxB is the rated maximum output voltage for unit B.
c. Program overcurrent value of unit A (IocsetA) to 1.1 x current limit for power assembly
(step 3a).
d. Program overvoltage value of unit A (VovsetA) to 1.1 x VsetA (step 3b).
4. Program unit B as follows:.
a. Program IsetB to approximate ly 1.01 to 1.02 x Iset A (step 3a). This maximum current
limit is never used except in the unlikely event that the current limit of Unit A is not work-
ing.
b. Program VsetB to (Eo – VsetA) (VsetA is set in step 3b).
c. Program overcurrent value of unit B (IocsetB) to 1.1 x IsetB (step 4a).
d. Program overvoltage value of unit B (VovsetB) to 1.1 x VsetB (step 4b).
5. To apply power to the load:
a. If load switch used, close the switch.
b. If load switch not used, press POWER ON/OFF key (once) on unit B, then unit A.
6. To disable power to the load:
a. If load switch used, open the switch.
b. If load switch not used, press POWER ON/OFF key once: first on unit A, then on unit B.
c. Alternative: Turn both units off by setting POWER switch to off (down) position, first on
unit A, then on unit B.
3-54 BHK-MG (OPR) 032816
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