KEPCO®
THE POWER SUPPLIER™
OPERATOR’S MANUAL
SERIES BHK-MG
40 WATT POWER SUPPLY
1/2 RACK VOLTAGE/CURRENT-STABILIZED DC SOURCE
KEPCO INC.
An ISO 9001 Company.
BHK-MG 40 WATT
POWER SUPPLY
ORDER NO. REV. NO.
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.
MODEL
©2016, KEPCO, INC
P/N 243-0970-r6
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
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)
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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 Cl. 6, Cl. 7, Cl.8, Cl. 9 and EN610101 annex F)
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, and as such depends upon proper connection to protective earth for safety from electric shock. (EN61010-1 Cl. 6.5.4)
4. This power supply 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 Cl.
6.5.4 and Cl.6.10.1)
5. This power supply has secondary output circuits that are considered hazardous, and which reach 40
VA at a potential of 300V or more.
6. The output wiring terminals of this power supply have not been evaluated for field wiring and, therefore, must be properly configured by the end product manufacturer prior to use.
7. 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 Cl.
9.6.2)
8. 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-XXXX COND/CONFORM 030916
SAFETY INSTRUCTIONS
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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) 030916 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.......................................................................................................................................... 1-2
1.4 Features.................................................................................................................................................. 1-9
1.4.1 Local Control...................................................................................................................................... 1-9
1.4.2 Remote Control.................................................................................................................................. 1-9
1.4.2.1 Digital Programming .................................................................................................................... 1-9
1.4.2.2 Analog Programming................................................................................................................... 1-9
1.4.2.3 Analog Readback......................................................................................................................... 1-9
1.4.3 Digital Calibration............................................................................................................................... 1-9
1.4.4 Overvoltage/Overcurrent Protection.................................................................................................. 1-10
1.4.5 User-defined Voltage/Current Limits.................................................................................................. 1-10
1.4.6 Nonvolatile Storage of Programmed Sequences or Active Settings.................................................. 1-10
1.4.7 Current Measurement Scale.............................................................................................................. 1-11
1.4.8 Fast Mode/Slow Mode Selection....................................................................................................... 1-11
1.4.9 Built-in Protection............................................................................................................................... 1-11
1.4.10 Analog Readback and Flag Signals Available for Customer Use...................................................... 1-12
1.4.11 External Trigger Port.......................................................................................................................... 1-12
1.4.12 Current Sink Capability...................................................................................................................... 1-13
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................................................................................................................ 2-7
2.6 Installation............................................................................................................................................... 2-8
2.6.1 Bench Top Use.................................................................................................................................. 2-8
2.6.2 Rack Mounting................................................................................................................................... 2-9
2.7 Wiring Instructions................................................................................................................................... 2-9
2.7.1 Safety Grounding............................................................................................................................... 2-9
2.7.2 Source Power Connections............................................................................................................... 2-9
2.7.3 D-C Output Grounding....................................................................................................................... 2-9
2.7.4 Power Supply/Load Interface............................................................................................................. 2-10
2.7.4.1 Cable Recommendations............................................................................................................. 2-11
2.7.5 Load Connection - General................................................................................................................ 2-11
2.7.5.1 Local Sensing/Remote Sensing Select........................................................................................ 2-12
2.7.5.2 Fast Mode/Slow Mode Select...................................................................................................... 2-12
2.7.5.3 Grounding Network Configuration................................................................................................ 2-12
2.7.5.4 Positive Output, Negative Terminal Grounded ............................................................................ 2-13
2.7.5.5 Negative Output, Positive Terminal Grounded ............................................................................ 2-13
2.8 Operating Configuration.......................................................................................................................... 2-13
2.9 Status Port............................................................................................................................................... 2-14
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 ................................................................................................................... 3-6
3.2.7.2 Disabling DC Output Using Remote On/Off Port ........................................................................ 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 Setting Overvoltage or Overcurrent Protection................................................................................. 3-8
3.2.11 Changing Maximum Voltage or Current Value ................................................................................. 3-9
3.2.12 Storing Power Supply Output Settings.............................................................................................. 3-9
3.2.13 Recalling Stored Output Settings...................................................................................................... 3-10
3.2.14 Firmware Version.............................................................................................................................. 3-10
3.2.15 Local Mode Programming of the Power Supply................................................................................ 3-10
3.2.15.1 Creating or Modifying a Program (Program Edit Mode).............................................................. 3-10
3.2.15.1.1 Modifying Programmed Time Interval..................................................................................... 3-12
3.2.15.1.2 Time Interval Accuracy...........................................................................................................3-12
3.2.15.2 Running a Program..................................................................................................................... 3-12
3.2.15.3 Stepping Through a Program...................................................................................................... 3-12
3.2.15.4 Cycling a Program....................................................................................................................... 3-13
3.2.15.5 Running a Program Once ........................................................................................................... 3-13
3.2.15.6 Stopping a Running Program............................................. ... ...................................................... 3-13
3.2.15.7 Sample Program......................................................................................................................... 3-13
3.2.16 Calibration......................................................................................................................................... 3-13
3.3 Remote Mode Programming Using SCPI commands via IEEE 488 (GPIB). Bus .................................. 3-14
3.3.1 IEEE 488 (GPIB) Bus Protocol .............................................................................................
3.3.2 DCL Control...................................................................................................................................... 3-15
3.3.3 Changing the GPIB Address............................................................................................................. 3-16
3.3.4 External Trigger ................................................................................................................................ 3-16
3.3.5 Programming Techniques to Optimize performance ........................................................................ 3-16
3.3.5.1 Programming Voltage/Current Limit and Current/Voltage Limit.................................................. 3-16
3.3.5.2 Making Sure the Previous Command is Complete ..................................................................... 3-17
3.4 BHK-MG VISA Instrument driver........................................................................................... .. ............... 3-18
3.5 RS232-C Operation................................................................................................................................ 3-19
3.5.1 Setting RS 232 Baud Rate................................................................................................................ 3-19
3.5.2 Serial INterface................................................................................................................................. 3-19
3.5.3 RS 232 Implementation .................................................................................................................... 3-19
3.5.3.1 Echo Mode.................................................................................................................................. 3-20
3.5.3.2 Prompt Method............................................................................................................................ 3-21
3.5.3.3 XON XOFF Method..................................................................................................................... 3-21
3.5.4 Isolating RS 232 Communication Problems ..................................................................................... 3-21
3.6 Programming Techniques to Optimize performance.............................................................................. 3-22
3.6.1 Example of Proper Programming...................................................................................................... 3-22
3.6.2 Explanation of Programming Techniques......................................................................................... 3-22
3.7 SCPI Programming................................................................... .............................................................. 3-22
3.7.1 SCPI Messages ................................................................................................................................ 3-23
3.7.2 Common Commands/Queries .......................................................................................................... 3-23
3.7.3 SCPI Subsystem Command/Query Structure................................................................................... 3-23
3.7.3.1 ABORt Subsystem...................................................................................................................... 3-23
3.7.3.2 INITiate Subsystem.....................................................................................................
3.7.3.3 LIST Subsystem.......................................................................................................................... 3-23
3.7.3.4 MEASure Subsystem.................................................................................................................. 3-23
3.7.3.5 OUTPut Subsystem .................................................................................................................... 3-23
............ 3-14
................ 3-23
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3.7.3.6 Instrument Subsystem................................................................................................................. 3-24
3.7.3.7 STATus Subsystem..................................................................................................................... 3-24
3.7.3.8 System Subsystem...................................................................................................................... 3-24
3.7.3.9 TRIGger subsystem..................................................................................................................... 3-24
3.7.3.10 [SOURce:]VOLTage and [SOURce:]CURRent Subsystems....................................................... 3-24
3.7.3.11 CALibrate Subsystem.................................................................................................................. 3-24
3.7.4 Program Message Structure.............................................................................................................. 3-26
3.7.4.1 Keyword....................................................................................................................................... 3-26
3.7.4.2 Keyword Separator...................................................................................................................... 3-27
3.7.4.3 Query Indicator............................................................................................................................ 3-27
3.7.4.4 Data ............................................................................................................................................. 3-27
3.7.4.5 Data Separator............................................................................................................................. 3-27
3.7.4.6 Message Unit Separator.............................................................................................................. 3-27
3.7.4.7 Root Specifier .............................................................................................................................. 3-27
3.7.4.8 Message Terminator.................................................................................................................... 3-28
3.7.5 Understanding The Command Structure........................................................................................... 3-28
3.7.6 Program Message Syntax Summary................................................................................................. 3-29
3.7.7 SCPI Program Examples................................................................................................................... 3-29
3.8 Remote Programming Using Analog Programming Terminals................................................................ 3-30
3.8.1 Analog Programming Warnings and Cautions................................................................................... 3-33
3.8.2 Programming with external resistance............................................................................................... 3-34
3.8.2.1 Voltage Mode............................................................................................................................... 3-36
3.8.2.2 Current Mode............................................................................................................................... 3-37
3.8.3 Programming with external voltage using a low impedance Voltage source..................................... 3-37
3.8.3.1 Voltage Mode............................................................................................................................... 3-41
3.8.3.2 Current Mode............................................................................................................................... 3-42
3.8.4 Programming with external voltage using a high impedance, low level (1V) Voltage source............ 3-42
3.8.4.1 Voltage Mode............................................................................................................................... 3-45
3.8.4.2 Current Mode............................................................................................................................... 3-45
3.8.5 Programming with external current source (1 mA) ............................................................................ 3-46
3.8.5.1 Voltage Mode............................................................................................................................... 3-48
3.8.5.2 Current Mode............................................................................................................................... 3-48
3.9 Operating Modes..................................................................................................................................... 3-49
3.9.1 Slow/Fast mode of operation............................................................................................................. 3-49
3.9.2 Series operation................................................................................................................................. 3-51
3.9.2.1 Automatic series operation.......................................................................................................... 3-52
3.9.2.2 Master-slave series operation (Automatic Tracking).................................................................... 3-55
3.9.2.2.1 Voltage Mode Operation.........................................................................................................3-55
3.9.2.2.2 Current Mode Operation .........................................................................................................3-58
3.9.3 Parallel operation............................................................................................................................... 3-60
3.9.3.1 Automatic parallel operation ........................................................................................................ 3-61
3.9.3.2 Master-slave parallel operation.................................................................................................... 3-63
3.9.3.2.1 Voltage Mode Operation.........................................................................................................3-64
3.9.3.2.2 Current Mode Operation .........................................................................................................3-66
SECTION 4 - CALIBRATION
4.1 General.................................................................................................................................................... 4-1
4.2 Equipment Required................................................................................................................................ 4-1
4.3 Calibration Description............................................................................................................................ 4-1
4.4 Calibration Using Front Panel Keys ........................................................................................................ 4-2
4.4.1 Voltage Calibration ............................................................................................................................ 4-2
4.4.2 Current Calibration............................................................................................................................. 4-3
4.5 Calibration Using IVI Driver..................................................................................................................... 4-4
4.5.1 Setup ................................................................................................................................................. 4-4
4.5.2 Main Control Panel............................................................................................................................ 4-5
4.5.3 Calibration Controls........................................................................................................................... 4-6
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4.5.4 Calibration Procedure....................................................................................................................... 4-7
4.6 Changing the Calibration Password ....................................................................................................... 4-9
4.7 Restoring Previous Calibration Values................................................................................................... 4-9
4.8 Restoring Factory Calibration Values..................................................................................................... 4-9
4.9 Calibration Storage................................................................................................................................. 4-10
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:CONT inuous? Query................................................................................................................. B-5
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-6
B.21 [SOURce:]LIST:CURRent Command..................................................................................................... B-6
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-7
B.28 [SOURce:]LIST:DWELl:POINts? Query................................................. ... ..................................... .. ... ... B-7
B.29 [SOURce:]LIST:QUERy Command.................................... ... ... .................................................. ............ B-7
B.30 [SOURce:]LIST:QUERy? Query.................................................. .. ......................................................... B-7
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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-10
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-11
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:[:LEVel]TRIGgered[:AMPlitude] Command........................................................... B-11
B.47 [SOURce:]CURRent:[:LEVel]TRIGgered[:AMPlitude] ? Query............................................................... B-11
B.48 [SOURce:]VOLTage[:LEVel][:IMMediate][:AMPlitude]
B.49 [SOURce:]VOLTage[:LEVel][:IMMediate][:AMPlitude]? Query............................................................... B-12
B.50 [SOURce:]VOLTage:LIMit[:HIGH] Command......................................................................................... B-12
B.51 [SOURce:]VOLTage:LIMit[:HIGH]? Query............................................................................... ............... B-12
B.52 [SOURce:]VOLTage:MODE Command.................................................................................................. B-13
B.53 [SOURce:]VOLTage:MODE? Query....................................................................................................... B-13
B.54 [SOURce:]VOLTage:PROTection[:LEVel] Command............................................................................. B-13
B.55 [SOURce:]VOLTage:PROTection[:LEVel]? Query.................................................................................. B-13
B.56 [SOURce:]VOLTage:[:LEVel]TRIGgered[:AMPlitude] Command........................................................... B-13
B.57 [SOURce:]VOLTage:[:LEVel]TRIGgered[:AMPlitude]? Query............................................... .. ... ............ B-13
B.58 [SOURce:]FUNCtion:MODE? Query...................................................................................................... B-14
B.59 STATus:OPERation:CONDition? Query................................................................................................. B-14
B.60 STATus:OPERation:ENABle Command................................................................................................ B-14
B.61 STATus:OPERation:ENABle? Query ..................................................................................................... B-15
B.62 STATus:OPERation[:EVENt] Query....................................................................................................... B-15
B.63 STATus:PRESet Command................................................................................................................... B-15
B.64 STATus:QUEStionable[:EVENt]? Query ................................................................................................ B-16
B.65 STATus:QUEStionable:CONDition? Query............................................................................................ B-16
B.66 STATus:QUEStionable:ENABle Command............................................................................................ B-16
B.67 STATus:QUEStionable:ENABle? Query................................................................................................. B-16
B.68 SYSTem:BEEP Command..................................................................................................................... B-16
B.69 SYSTem:COMMunication:GPIB:ADDRess
B.70 SYSTem:COMMunication:GPIB:ADDRess? Query................................................................................ B-17
B.71 SYSTem:COMMunication:SERial:BAUD Command.............................................................................. B-17
B.72 SYSTem:COMMunication:SERial:BAUD? Query................................................................................... B-17
B.73 SYSTem:COMMunication:SERial:ECHO
B.74 SYSTem:COMMunication:SERial:ECHO? Query................................................................................... B-17
B.75 SYSTem:COMMunication:SERial:PACE Command.............................................................................. B-17
B.76 SYSTem:COMMunication:SERial:PACE? Query................................................................................... B-17
B.77 SYSTem:COMMunication:SERial:PROMpt
B.78 SYSTem:COMMunication:SERial:PROMpt?
B.79 SYSTem:ERRor? Query................................................................................................................ ... ... ... B-18
B.80 SYSTem:ERRor:CODE? Query ............................................................................................................. B-18
Command ..................................................... ... ................. B-17
Command ..................................................... ... .................... B-17
Command..................................................... .................... B-18
QUERY........................................................................... B-18
Command.................................................... ... ... B-12
BHK 1/2 RACK 020498 v
TABLE OF CONTENTS
SECTION PAGE
B.81 SYSTem:ERRor:CODE:ALL? Query ...................................................................................................... B-18
B.82 SYSTem:KLOCk Command.................................................................................................................... B-18
B.83 SYSTem:KLOCk? Query ......................................................................................................... ... ... ......... B-19
B.84 SYSTem:PASSword:CENable Command .............................................................................................. B-19
B.85 SYSTem:PASSword:CDISable Command ............................................................................................. B-19
B.86 SYSTem:PASSword:NEW Command .................................................................................................... B-19
B.87 SYSTem:PASSword:STATe? Query....................................................................................................... B-19
B.88 SYSTem:SECurity:IMMediate Command............................................................................................... B-19
B.89 SYSTem:VERSion? Query ...................................................................................................... ............... B-20
B.90 TRIGger:SOURce Command..................................... .................................................. .......................... B-20
vi BHK 1/2 RACK 030916
LIST OF FIGURES
FIGURE TITLE PAGE
1-1 BHK-MG 40W Series Programmable Power Supply.................................................................................... xii
1-2 BHK 40W Series Power Supply, Mechanical Outline Drawing .................................................................. 1-6
1-3 RA 24 Rack Adapter with two 1/2 Rack BHK-MG 40W Units .................................................................... 1-8
1-4 Connector A2J5 Location........................................................................................................................... 1-10
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 ........................................................... 2-13
2-6 Status Port Opto-coupler Active “LOW” Configuration............................................................................... 2-14
2-7 Status Port Opto-coupler Active “HIGH” Configuration.............................................................................. 2-14
3-1 LCD Power On States................................................................................................................................ 3-5
3-2 Programming Example to Verify Previous Command has Completed....................................................... 3-18
3-3 RS 232 Implementation.................................... .................................................. ........................................ 3-20
3-4 Tree Diagram of SCPI Commands Used with BHK-MG 40W Power Supply............................................. 3-25
3-5 Message Structure..................................................................................................................................... 3-26
3-6 Typical Example Of BHK-MG 40W Power Supply Program Using SCPI Commands ............................... 3-30
3-7 Analog Voltage Programming, Simplified Diagram .................................................................................... 3-31
3-8 Analog Current Programming, Simplified Diagram .................................................................................... 3-31
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).............................. 3-43
3-16 Analog Programming of Output Current (Current Mode) or Current
Limit (Voltage Mode) using High Impedance, Low Level (1V) Voltage Source (VS).............................. 3-44
3-17 Analog Programming of Output Voltage (Voltage Mode) or Voltage
Limit (Current Mode) using Current Source (1mA) (CS) ........................................................................ 3-46
3-18 Analog Programming of Output Current (Current Mode) or Current
Limit (Voltage Mode) using Current Source (1mA) (CS) ........................................................................ 3-47
3-19 Slow Mode/Fast Mode Operation............................................................................................................... 3-50
3-20 Series Automatic Configuration.................................................................................................................. 3-54
3-21 Series Master-Slave (Voltage Mode) Configuration................................................................................... 3-57
3-22 Series Master-Slave (Current Mode) Configuration................................................................................... 3-58
3-23 Parallel Automatic Configuration............................................... ... ... ........................................................... 3-62
3-24 Parallel Master-Slave (Voltage Mode) Configuration ................................................................................. 3-64
3-25 Parallel Master-Slave (Current Mode) Configuration ................................................................................. 3-67
4-1 Input VISA Resource Descriptor ................................................................................................................ 4-5
4-2 Main Control Panel, Typical ....................................................................................................................... 4-5
4-3 Calibration Controls.................................................................................................................................... 4-6
4-4 Password Entry..................................... .. ................................................ ... ................................................ 4-7
4-5 Voltage Calibration..................................................................................................................................... 4-7
4-6 Current Magnifier Window.......................................................................................................................... 4-8
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 1/2 RACK 030916
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 1/2 RACK 030916
LIST OF TABLES
TABLE TITLE PAGE
1-1 Model Parameters .......................................................................................................................................1-2
1-2 BHK-MG 40W Specifications ......................................................................................................................1-2
1-3 Connector A2J5 Signal Descriptions ..........................................................................................................1-12
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 IEEE 488 Port Connector Pin Assignments ................................................................................................2-4
2-3 Status and Remote On/Off Port Connector Pin Assignments .....................................................................2-4
2-4 RS 232C PORT Input/Output Pin Assignments ..........................................................................................2-5
2-5 External Trigger Port Pin Assignments .......................................................................................................2-5
2-6 Rear Output Terminal Strip A6TB1, Terminal Assignments .................................................. ... ...................2-5
2-7 Voltage Programming Terminal Strip A6TB2, Terminal Assignments ........................................................2-5
2-8 Current Programming Terminal Strip A6TB3, Terminal Assignments .........................................................2-6
2-9 Internal Jumper Configuration .....................................................................................................................2-14
3-1 LCD Messages ...........................................................................................................................................3-2
3-2 Key Functions .............................................................................................................................................3-2
3-3 Error Conditions ..........................................................................................................................................3-5
3-4 Memory Location Worksheet ......................................................................................................................3-11
3-5 Sample Program (Model BHK-MG 500-80MG) ...........................................................................................3-13
3-6 IEEE 488 (GPIB) Bus Interface Functions ..................................................................................................3-14
3-7 IEEE 488 (GPIB) Bus Command Mode Messages .....................................................................................3-15
3-8 IEEE 488 (GPIB) Bus Data Mode Messages ....................................................................................
3-9 Rules Governing Shortform Keywords ........................................................................................................3-27
3-10 Feedback Resistor and Current Sensing Resistor Values ..........................................................................3-35
4-1 VISA Resource String Corresponding to Interface .....................................................................................4-4
4-2 Calibration Panel Functions ........................................................................................................................4-6
4-3 Factory Default Calibration Passwords .......................................................................................................4-9
4-4 Calibration Storage .....................................................................................................................................4-10
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
..........3-15
BHK 1/2 RACK 03916 ix/(viii Blank)
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 no operator serviceable components or
adjustments inside the unit. High voltage components 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 the output is disabled, whether by
the OUTPUT ON/OFF key, SCPI command via GPIB or RS 232 interface, or via the Status and Remote
On/Off Port, an internal solid-state switch sets the voltage/current references to zero, resulting in zero output from the power supply. In the case of the OUTPUT ON/OFF key or SCPI command, if the solid state
switch fails, and the output is higher than 8V, and the current is higher than two LSBs, a shutdown
sequence begins: the unit beeps and flashes the message Power Down in XX sec for 10 seconds as
XX counts down from 10 to 0. After 10 seconds the input circuit breaker trips OFF. If the circuit breaker
does not trip OFF, BHK Failure is displayed on the LCD.
There are no operator serviceable p art s 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.
BHK-MG 030916 xi
FIGURE 1-1. BHK-MG 40W SERIES PROGRAMMABLE POWER SUPPLY
xii BHK-MG030916
1.1 SCOPE OF MANUAL
WARNING
This manual contains instructions for the installation, operation and service of the Half Rack
BHK-MG 40W series of 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 40W 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 as listed in Table1-1.
Although designed as a stand-alone bench top unit, the half-rack cross section permits mounting two units side by side in a standard 19-inch wide rack using Kepco’s RA 24 Rack Adapter
(see Figure 1-3). Connections can be made at both rear output terminals (recommended for
rack mounted configurations) and front output terminals (recommended for bench applications).
Rear connections are made from a drawer-type access panel that is pulled out for installation of
connections, and then inserted and secured during operation. 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 40W Power Supplies of fer 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 40W 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 the IEEE 488.2 (GPIB) communication bus. 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.
BHK-1/2-MG (OPR) 030916 1-1
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.
TABLE 1-1. MODEL PARAMETERS
OUTPUT
MODEL
NUMBER
BHK 300-130MG 0 - 300 0 - 130 39 0.115 See Note 15.4 See Note
BHK 500-80MG 0 - 500 0 - 80 40 0.313 See Note 41.7 See Note
BHK 1000-40MG 0 - 1000 0 - 40 40 4.25 See Note 166.7 See Note
BHK 2000-20MG 0 - 2000 0 - 20 40 5.0 See Note 666.7 See Note
NOTE: Contact Kepco for assistance.
VOLTAGE
RANGE
(VOLTS)
OUTPUT
CURRENT
RANGE
(mA)
MAXIMUM
OUTPUT
POWER
(WATTS)
OUTPUT EQUIVALENT IMPEDANCE (FAST MODE)
VOLTAGE MODE
(SERIES R–L)
R
(Ohms)
d-c
L (mH)
CURRENT MODE
(PARALLEL R–C)
R
(MOhms)
d-c
C (F)
TABLE 1-2. BHK-MG 40W SPECIFICATIONS
SPECIFICATION RATING/DESCRIPTION CONDITION
INPUT CHARACTERISTICS
a-c Voltage nominal (switch select-
range (switch selectable) 105-125/210-250V a-c
Frequency nominal 50/60Hz
Current 115V a-c 1.1A a-c Nominal power at output
230V a-c 0.6A a-c
115/230V a-c Single phase
able)
range 47-63Hz
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, tolerance 80% to 100% of rating; it flows until the output reaches the lower voltage.
Type of Stabilizer Linear with automatic cross-
over
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
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 Current measurement requires calibrated
Voltage 0.05% of rating
Current 0.05% of rating 10-100% of rating
0.01% of rating <10% of rating (automatic 10X magnifier)
max Input voltage
O
Current 0.002% I
O
max
Voltage/Current
about analog programming and readback.
shunt
shunt
105-125/210-250V a-c
1-2 BHK-1/2-MG (OPR) 030916
TABLE 1-2. BHK-MG 40W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
OUTPUT CHARACTERISTICS (CONTINUED)
Load effect Voltage 0.005% EO max no load - full load
Current 0.015% I
Temperature effect
(per degree C)
Voltage 0.01% E
Current 0.02% I
Time effect Voltage 0.01% E
Current 0.02% I
Ripple (rms/p-p)
(Slow Mode)
Voltage: 0.004% / 0.04% E
Current: 0.02% / 0.2% I
max short - full load
O
max Ambient temperature
O
max
O
max 0.5-8.5 hours
O
max
O
max Minus output terminal connected to GND.
O
max
O
0 to 50° C
Ambient temperature: 25° C
Voltage: Nominal load
Current: Short with calibrated shunt.
Programming
rise time (R)/fall time (F)
Voltage Fast Mode:
Slow Mode:
s (R)/180s (F)
180
60ms (R)/75ms (F)
(1)
E
Load
Vout between zero and E
max/IO max,
O
sured between 10% and 90% of E
Current Fast Mode:
Slow Mode:
s (R)/200s (F)
200
60ms (R)/75ms (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 5% E
Slow Mode 0.5% E
Source Current Fast Mode 50% I
Voltage 2.5 KHz Load = E
max/100 sec Vout=400 Vdc and load switched
O
max/1 msec
O
max/100 sec Iout = IO max
O
between infinity and 400/I
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
max and back to zero.
O
response to a square waveform between
zero and I
max and back to zero.
O
Overshoot None Turn ON/Turn OFF
Output Impedance See Table 1-1.
Remote Sensing Range
(default = local sensing)
D-C Isolation voltage BHK 300-130MG,
BHK 500-80MG,
0.5 V d-c per lead Provisions for 4-terminal (Kelvin) connection to load
1KV d-c or p-p plus max.
output voltage
Between either output terminal and
ground
BHK 1000-40MG
BHK 2000-20MG 0.5KV d-c or p-p plus max.
output voltage
(1) Programming rise time (R)/fall time (F) for BHK 2000-20MG (Voltage, Fast Mode): 275
Between either output terminal and
ground
s (R)/275s (F)
max, mea-
O
O
max, measured
O
max
O
max
O
max/EO max (from
O
max
BHK-1/2-MG (OPR) 030916 1-3
TABLE 1-2. BHK-MG 40W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
OUTPUT CHARACTERISTICS (CONTINUED)
Withstand voltage (All models) 1350V a-c/1 min Between shorted inputs and chassis
BHK 300-130MG 1950V d-c/1 min Between shorted outputs and chassis.
BHK 500-80MG 2250V d-c/1 min
BHK 1000-40MG
BHK 2000-20MG
Chassis connection to ground
resistance
Leakage Current 25
Enable/Disable Output Power Local Front panel Keypad: disable both digital and analog programming sig-
Remote - IEEE 488 (GPIB) port
Output Display Two decimal places are used for voltage settings and three decimal
Protection Overtemperature: See PAR. 1.4.9a
Overvoltage/Overcurrent: 0 to 1.1 x EOmax
Uneven voltage
in pass element:
AC line failure: See PAR. 1.4.9e
Interruption between sens-
ing and power terminals:
Overload of main or
auxiliary power trans-
former:
Internal Output Capacitor
(Default state = internal output
capacitor connected.)
Reference Voltages for analog programming:
Status & Remote On/Off Port
Status: (Output Signal) Type Output transistor (open collector) from an optocoupler
Output Ratings Ic = 8mA d-c, Vceo = 40V d-c, Pd = 150mW@25° C
Remote
on/off:
(input
signals)
BHK 300-130MG 6.6
BHK 500-80MG 3.0
BHK 1000-40MG
BHK 2000-20MG
NO Relay contact Max R
NC Relay contact Min R
2800V d-c/1 min
0.1 Ohm 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.
Disables both digital and analog pro-
- RS 232 port
- Status & Remote On/Off
port
- TTL signal
- NO relay contact
- NC relay contact type.
- Trigger port (shutdown line)
places for current settings (except that only one decimal place is used
for setting voltage on Models BHK 1000-40MG and BHK 2000-20MG).
0 to 1.1 x IOmax
gramming signals. Shutdown line is for
disable only - removing the signal does
not reenable the output.
See PAR. 1.4.4
See PAR. 1.4.9c
See PAR. 1.4.9f
See PAR. 1.4.9g
F ±10%
F ±10%
F±10%
0.94
F±10%
0.21
+10 ±-0.2V d-c
–10 ±-0.2V d-c
Logic Saturated transistor when AC line is present
TTL FAN - in = 1
= 100 ohms
CLOSE
= 100 Kohms
OPEN
All internal output capacitors are
non-polarized type.
max.10 mA d-c
NOTE: Enabled/disabled by on-board
jumper.
1-4 BHK-1/2-MG (OPR) 030916
TABLE 1-2. BHK-MG 40W SPECIFICATIONS (Continued)
SPECIFICATION RATING/DESCRIPTION CONDITION
OUTPUT CHARACTERISTICS (CONTINUED)
Series Connection Automatic or Master-Slave
Operation, limited by the d-c
isolation limit voltage
Parallel Connection Automatic or Master-Slave
Operation
For slave unit, use analog programming
only.
For slave unit, use analog programming
only.
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 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 26 lbs. Unpacked
Metric 12 Kg
a-c source connections Front Circuit Breaker, 2-pole
Rear Detachable IEC 3-wire type
connector
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 connector).
Digital display
front panel
Analog control using two rear panel terminal strips (10 positions) for voltage and current
Voltage, current, mode, settings, menu, program, etc.
±Output, ±Sense, Ground, Internal
Capacitor (–), Grounding Network
2 x 16 character alphanumeric LCD with
LED backlight
BHK-1/2-MG (OPR) 030916 1-5
FIGURE 1-2. BHK 40W SERIES POWER SUPPLY, MECHANICAL OUTLINE DRAWING (SHEET 1 OF 2)
1-6 BHK-1/2-MG (OPR) 030916
FIGURE 1-2. BHK 40W SERIES POWER SUPPLY, MECHANICAL OUTLINE DRAWING (SHEET 2 OF 2)
BHK-1/2-MG (OPR) 030916 1-7
FIGURE 1-3. RA 24 RACK ADAPTER WITH TWO 1/2 RACK BHK-MG 40W UNITS
1-8 BHK-1/2-MG (OPR) 030916
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. Calibr ation
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 40W Power Supply can be accomplished either through digital
or analog programming.
1.4.2.1 DIGITAL PROGRAMMING
Digital control is available directly via the IEEE 488.2 (GPIB) 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 3.7 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 –10
Vdc 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.
3.8 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 (uncalibrated), 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 Tabl e 1- 5 to ob tain th e A 2J5 m a tin g con n ec to r.
See Figure 1-4 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 40W Power Supply contains no internal adjustments. Calibration is done entirely
via the front panel keypad and LCD, using a calibrated DVM and a corresponding precision
shunt resistor. Calibration instructions appear on the front panel LCD after a password is
entered.
Calibration constants for programming a nd read -back act ivities are calculated by the m icrocontroller and stored in the non-volatile memory. No internal adjustments are necessary The previous calibration is saved and can be restored if desired. T he original factory ca libration ca n also
be restored. Refer to Section 4 for more information.
BHK-1/2-MG (OPR) 030916 1-9
FIGURE 1-4. 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
max, 0 to 1.1 x IOmax. If the output volt-
O
age/current is maintained at or above the overvoltage/overcurrent protection value for more
than 9ms, the protection circuit cuts the pass eleme nt off, discharges the outp ut 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 overcurrent
O
protection. Refer to PAR. 3.2.10 for more information.
1.4.5 USER-DEFINED VOLTAGE/CURRENT LIMITS
The BHK-MG 40W Power Supply can be programmed not to exceed user-defined values that
can be lower than the maximum values. For example, the BHK 500-80MG, which has maximum
output values of 500V d-c, 0.08A d-c, can be limited to 100V d-c, 0.04A d-c for working with circuitry that might be damaged by higher levels. Once the limits are set, the power supply
becomes, in effect a 100V d-c, 0.04A d-c supply and values exceeding the limit values will not
be accepted. Refer to PAR. 3.2.11 for more information.
1.4.6 NONVOLATILE STORAGE OF PROGRAMMED SEQUENCES OR ACTIVE SETTINGS
The BHK-MG 40W Power Supply contains 40 memory locations that can be used either to preprogram a sequence 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. V alue s are stored in the nonvolatile memory, and are retained when the unit is turned
off. Refer to PAR. 3.2.15 for more information.
1-10 BHK-1/2-MG (OPR) 030916
The same 40 memory locations are also available to save the active pr ogr amm ed settings ( vol tage, current, overvoltage, overcurrent). The saved setting can be recalled by specifying the
memory location. Refer to PAR’s. 3.2.12 and 3.2.13 for more information.
1.4.7 CURRENT MEASUREMENT SCALE
Measurement of a decreasing output current of the power supply that falls below 8.98% ±0.1%
of the rated value is automatically measured with increased resolution/accuracy by a factor of
10 until the current rises above 9.69% ±0.1% of rated value.
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 response to step or dynamic 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. 3.9.1 for more information.
1.4.9 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 2.5ms, the following actions ar e initiated: th e
pass element is cut off, the output capacitor is discharged, and the unit is turned off by tripping the circuit breaker. A flag is sent to the host computer via a dedicated line of the Status
and Remote On/Off port.
b. Overvoltage/overcurrent at the output. See PAR. 1.4.4
c. Uneven voltage in the pass and sink elements . Voltage is monitored across different tran-
sistors of the pass and sink elements. If uneven voltage continues for more than 20ms, the
pass element is cut 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 and
Remote On/Off Port connector)
d. Input Voltage Selector set incorrectly. If the selector is set to 115V a-c and the input volt-
age is 230V a-c, the input circuit breaker will be tripped without delay. A flag is sent to the
host computer on a dedicated line (Status and Remote On/Off Port).
e. AC line failure. If AC line is missing for more than 50 ms, a flag is sent to the host computer
on a dedicated line (Status Port connector). In addition, if the jumper at A3-JP2 is installed
(default state), the pass element is cut off, the output capacitor is discharged, and the
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.
BHK-1/2-MG (OPR) 030916 1-11
g. Overload of the main or auxiliary power transformer. If input current of the main trans-
former exceeds 1.1A a-c @ 115V a-c or 0.6A a-c @ 230V a-c, the input POWER circuit
breaker is tripped to OFF, the pass element is cut off, the output ca p a citor is di schar ged, an d
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 current, to a maximum of
100 seconds for 25% above nominal current.
If input current of the auxiliary power transformer exceeds a predetermined value, the PTC
(Positive Thermal Coefficient) thermistor (in series with the primaries of the auxiliary transformers) resistance will increase, thus reducing the voltage across the primary of the corresponding transformer. If this occurs, the pass element will be cut off. In some circumstances,
depending upon which transformer is involved and whether an overcurrent condition is
detected during or after power-up, the input circ uit breaker may trip OFF.
h. Current Limit. The current through the p ass and sink eleme nts is m onitored. If this current is
1.5 times larger than the nominal value for more than 20ms , the pass element is cut off, the
output capacitor is discharged, and the POWER circuit breaker is tripped to OFF. A flag is
sent to the host computer via the Status and Remote On/Off Port.
1.4.10 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.
1.4.11 EXTERNAL TRIGGER PORT
The External Trigger Port provides two functions: a shutdown input can be used to immediately
shut down the power supply output (see PAR. 3.2.7.3) and a trigger input can be used to restore
the output to previously defined settings (see PAR. 3.3.4).
TABLE 1-3. CONNECTOR A2J5 SIGNAL DESCRIPTIONS
SIGNAL PIN. NO. VALUE TYPE
Step Down Flag 2
V-C Mode Flag 3
Source-sink Flag 4
Power GND 5 N/A
Current Monitor
(not calibrated)
Signal GND 7 N/A
Voltage Monitor
(not calibrated)
6
8
< –11V for steady or step-up output
> +11V for step-down output, or when protection circuit has functioned.
< –11V for CV (Constant Voltage) mode
> +11V for CC (Constant Current) mode
–11V for sink
> +11V for source
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)
Output of open loop Op Amp
(A2U2C) through 1K resistance.*
Output of open loop Op Amp
(A2U2A) through 1K resistance.*
Output of open loop Op Amp (A2U9)
through 1K resistance.*
Recommended to be used as Return
for signal at pin 2.
Output of closed loop Op Amp
(A2U14B) *
Recommended to be used as Return
for signals at pins 6 and 8.
Output of closed loop Op Amp
(A2U1B) *
* Recommended load equal to or greater than 10K ohms.
1-12 BHK-1/2-MG (OPR) 030916
1.4.12 CURRENT SINK CAPABILITY
BHK-MG 40W Series power supplies are able to sink up to 5% of the nominal curr ent when in
voltage mode and greater than 75% 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%. When the
BHK-MG 40W is in sink mode, the unit displays the word “Sink” an d the sink cur ren t va lue (n egative) on the front panel display. 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 curr ent 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 b e calc ulated directly by measuring T and either using
the above formula and the appropriate tolerance for I, or by comparing T to that of a known
capacitor value.
1.5 EQUIPMENT SUPPLIED
Equipment supplied with the unit is listed in Table 1-4.
TABLE 1-4. EQUIPMENT SUPPLIED
ITEM
Power Cord 118-0557 1
Plug housing for front panel output jack 142-0489 1
Contact (crimp, snap-in)) for plug housing 107-0361 2
Status and Remote On/Off Port mating connector 142-0488 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-1/2-MG (OPR) 030916 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 Connects BHK-MG 40W Power Supply to GPIB bus. SNC 488-1
IEEE 488 (GPIB) Cable, 2m long Connects BHK-MG 40W Power Supply to GPIB bus. SNC 488-2
IEEE 488 (GPIB) Cable, 4m long Connects BHK-MG 40W Power Supply to GPIB bus. SNC 488-4
Rack Adapter Allows rack mounting of two units side by side (see Figure 1-3). RA 24
Slide (2) Allows rack-mounted units to slide in and out. CS-01, -02, -03
External Trigger Port mating
connector
RS 232 Port Adapter Cable Kit Contains RJ 45 Patch cord, two RS 232 adapters (one with male
Mating connector for A2J5 (Analog Readback and Flags)
Allows access to external trigger function 142-0486 (Kepco)
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).
Allow user access to analog readback and flag signal; see T able 1-3
for details.
PART NUMBER
(Kepco)
110-QD-20-2, 22-2,
22-4 (Jonathan)
MDP-023 (Power
Dynamics)
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-1/2-MG (OPR) 030916
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-1/2-MG SERIES 030916 2-1
TABLE 2-1. CONTROLS, INDICATORS, AND CONNECTORS
CONTROL, INDICATOR,
CONNECTOR
FRONT PANEL (See Figure 2-1.)
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.
Output jack 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 2-2 for pin
STATUS AND REMOTE ON/OFF PORT Notifies host computer either that a-c input is not present or a major failure of
RS 232 PORT 8-pin connector telephone jack type used to connect to RS 232 bus. Adapter
EXTERNAL TRIGGER PORT 4-pin connector used to restore previously stored settings or to shut down the
OUTPUT TERMINALS barrier strip TB1
(See NOTE 1.)
V PROG terminal strip TB2
(See NOTE 1.)
mode, settings, menu, program, etc.
details.
REAR PANEL (See Figure 2-2.)
assignments).
power supply has occurred and allows remote on/off control of the unit (see
Table 2-3 for pin assignments).
cable kit (see Table 1-5) converts to 9-pin jack (see Table 2-4 for 9-pin assignments).
output (see Table 2-5 for pin assignments). NOTE: Mating connector is a 3-pin
plug.
Provides Power Supply output connection points. (See Table 2-6 for terminal
assignments)
Provides input/output signals for analog programming of output voltage or voltage limit. (See Table 2-7 for terminal assignments.)
I PROG terminal strip TB3
(See NOTE 1.)
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.
Terminal Drawer Closed detector
(see NOTE 2.)
NOTES 1. Accessible by loosening two captive screws and pulling out terminal drawer, and removing protective insulator (see
Figure 2-2).
2. The Terminal Drawer detector (located on PC board A3) and the a-c circuit beaker function as an interlock switch.
Provides input/output signals for analog programming of output current or current limit. (See Table 2-8 for terminal assignments.)
Provides protection when Terminal Drawer is open by tripping the a-c circuit
breaker to off.
2-2 BHK-1/2-MG SERIES 030916
FIGURE 2-2. BHK-MG SERIES, REAR PANEL CONTROLS AND CONNECTIONS
BHK-1/2-MG SERIES 030916 2-3
TABLE 2-2. 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
TABLE 2-3. STATUS AND REMOTE ON/OFF PORT CONNECTOR PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
1 Armature Relay control armature contact.
N-open Normally open relay control input: pins 1 - 2 open for output
STATUS AND
REMOTE ON/OFF
PORT
CONNECTOR A3J14
2
N-closed Normally closed relay control input: pins 1 - 3 closed for out-
3
4 5V Return Return for TTL control
5 Not Used.
6 TTL TTL control input: Logic 0 for unit ON, logic 1 for unit OFF.
Collector Collector of LED-transistor optocoupler. Notifies host com-
7
Emitter Emitter of LED-transistor optocoupler. Notifies host computer
8
ON, pins 1 - 2 closed for output OFF (Jumper A3JP1 should
be in the factory default position, between pins 1 and 2).
put ON, pins 1 - 3 open for output OFF (Jumper A3JP1
should be inserted between pins 2 and 3).
puter of absence of a-c input or a major power supply failure,
active “high” (see PAR 1.4.9), requires pin 8 to be connected
to the “–“ of the host computer d-c supply as described in
PAR.2.9.
of absence of a-c input or a major power supply failure, active
“low” (see PAR 1.4.9), requires pin 7 to be connected to the
“+“ of the host computer d-c supply as described in PAR. 2.9.
2-4 BHK-1/2-MG SERIES 030916
TABLE 2-4. RS 232C PORT INPUT/OUTPUT PIN ASSIGNMENTS
CONNECTOR PIN SIGNAL NAME FUNCTION
1 RTN Return 1 Signal Ground
2 Not Used Not Used 2 Receive Da ta
3 TXD Transmit Data 3 Transmit Data
RS 232
PORT
(connector A1J5)
4 RXD Receive Data 4 Data Terminal Ready (protocol not used)
5 RTN Return 5 Signal Ground
6 Not Used Not Used 6 Data Set Ready (protocol not used)
7 RTN Return 7 Request To Send (protocol not used)
8 RTN Return 8 Clear To Send (protocol not used)
PIN FUNCTION
Adapter Cable (P/N KIT 219-0436)
9 Signal Ground
TABLE 2-5. EXTERNAL 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.90.)
TABLE 2-6. REAR OUTPUT TERMINAL STRIP A6TB1, TERMINAL ASSIGNMENTS
TERMINAL SIGNAL NAME FUNCTION
1 – OUT C Connection to the internal output capacitor
2 – OUT Negative d-c output connection
3 –S Negative sense connection
4 GND Ground (chassis) connection
5 GND NET Grounding network connection
6 +S Positive sense connection
7 + OUT Positive d-c output connection
TABLE 2-7. VOLTAGE PROGRAMMING TERMINAL STRIP A6TB2, TERMINAL ASSIGNMENTS
TERMINAL SIGNAL NAME FUNCTION
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 programs 0 to 100% of EOmax.
10 SGND Signal common
BHK-1/2-MG SERIES 030916 2-5
TABLE 2-8. CURRENT PROGRAMMING TERMINAL STRIP A6TB3, TER MINAL ASSIGNMENTS
WARNING
TERMINAL SIGNAL NAME FUNCTION
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 programs 0 to
10 SGND Signal common
100% of IOmax.
2.3 SOURCE POWER REQU IREMEN TS
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 maximum AC current absorbed by the BHK-MG 40W Power Supply from the power source
is 1.1A a-c @115V a-c and 0.6A a-c @230V a-c; the power source must be able to deliver the
maximum current as well as surge current ten times larger than maximum.
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 two internal (d-c type) cooling
fans.
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).
2-6 BHK-1/2-MG SERIES 030916
2.5 PRELIMINARY OPERATIONAL CHECK
WARNING
Loc CV
0.000A0.000V (:_:_:)
NOTE: (:_:_:) indicates blinking colon (:), Command Entry status
(=_=_=) indicates blinking equal sign (=), Data Entry status
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 PA NEL (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.
The alphanumeric display (LCD) indicates the model and GPIB address. After a few seconds, the display presents the power supply default values: Local mode (LOC), Output On/
Off (Off), output voltage and current (0.000V 0.000A) and command entry status (see
Figure 2-3.). Overvoltage and overcurr ent protection are set to the maximum valu es (PAR.
1.4.4), but are not displayed. To enable the output of the BHK-MG, press the OUTPUT ON/
OFF key on the front pane l
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 output jack 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 500-80MG, 500V is the nominal output
voltage) and press ENTER. Output voltage will be displayed at bottom left of LCD. Verify
the LCD reads CV (constant voltage mode).
BHK-1/2-MG SERIES 030916 2-7
FIGURE 2-3. LCD POWER ON DEFAULTS
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 betwee n 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 outp ut by pressing OUTPUT ON/OFF key; verify LCD reads 0.0V and 0.0mA
within 0.05% of the nominal voltage of the unit.
10. Disconnect DVM and connect precision shunt (see PAR. 4.2) across front panel output terminals; connect DVM across shunt (sensing ter min a ls).
11. Using VSET key, set output voltage to 30V.
12. Similarly, using ISET key , program output cur rent to the nominal output current of the power
supply (e.g., for BHK 500-80MG, 80mA is the nominal output current).
13. Press OUTPUT ON/OFF key to enable the output of the unit. Verify the LCD reads
(constant current mode) and a small value for output voltage (RS x I
where R
= resistance of shunt in ohms and I
S
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
x 0.001) in volts,
= the actual value for current pro-
o (prog)
) and calculate the output current using the formula IO =V
DVM
o (prog)
DVM
CC
x
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.
2-8 BHK-1/2-MG SERIES 030916
2.6.2 RACK MOUNTING
Using a Kepco RA 24 Rack Adapter, two 1/2 rack BHK-MG 40W units can be mounted in a 19inch wide rack, after the bench-type feet are removed (see Figure 1-3). Optional slides for the
rack adapter (see Table 1-5) can be used to improve access to the unit.
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.
To access to the output and analog programming terminal strips it is necessary to pull out the
terminal drawer as follows:
1. Loosen two captive screws securing the terminal drawer to the rear panel.
2. Use the handle provided to pull out the terminal drawer.
3. Remove two scr ews attaching the protective insulato r to the terminal strip PC board, then
snap out the insulator and remove it.
4. Thread wires through wire-entry bushing before connecting to terminal strip.
5. After all connections have been completed, snap the insulator in place and secure with two
screws. Then insert the terminal drawer into the rear panel (taking care that the bottom of
the PC board/insulator engage the internal guides) and secure with two captive screws.
NOTE: The unit will not operate unless the terminal drawer is securely inserted in the rear
panel.
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 p art 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 recommended wiring, it is the customer's responsibility
to ensure that all applicable electric codes for safety grounding requirements are met.
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.
BHK-1/2-MG SERIES 030916 2-9
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 judgem ent and some amoun t of
empirical testing. If there is a choice in selecting either the positive or negative output of the
power supply for the d-c ground point, both sides should be tried, and preference 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; when r emote er ror 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 established 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. Care must be taken in measuring the ripple and noise
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.
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
2-10 BHK-1/2-MG SERIES 030916
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 500-80MG). 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 pair or twisted pair cables are recommended.
It is recommended that cable length not exceed 50 feet; for longer cable lengths, cont act Kepco.
2.7.5 LOAD CONNECTION - GENERAL
Load connections to the BHK-MG 40W Power Supply are achieved via the rear output terminal
strip (TB1); (+) and (-) outputs are also available at the jack 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 40W Power Supply is shipped from the factory configured as follows (factory
default configuration): local sensing, grounding network connected, slow mode, output isolated
from ground (floating). Th is 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 (TB1-6) MUST BE CONNECTED TO EITHER +OUT (TB1-7) (LOCAL) OR +LOAD (REMOTE), AND THE - S
TERMINAL (TB1-3) MUST BE CONNECTED TO EITHER –OUT (TB1-2) (LOCAL) OR
–LOAD (REMOTE).
Figures 2-4 and 2-5 are typical load connection diagrams illustrating the configurations
explained in the following paragraphs.
BHK-1/2-MG SERIES 030916 2-11
FIGURE 2-4. LOCAL SENSING, SLOW MODE SELECTED, GROUNDING NETWORK CONNECTED,
FLOATING OUTPUT (FACTORY DEFAULT CONFIGURATION)
2.7.5.1 LOCAL SENSING/REMOTE SENSING SELECT
Local sensing (factory default configuration) is established by connecting terminals TB1-6
(+S) to TB1-7 (+OUT) and TB1-2 (–OUT) to TB1-3 (–S) (see Fig ure 2 -4). T he po wer sup ply is
shipped with these connections installed for local sensing.
Remote sensing is established by removing the links between TB1-6, TB1-7 and TB1-2, TB1-3.
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 TB1-2 (–OUT) and TB1-1
(–OUT C) (see Figure 2-5). Slow mode (factory default configuration) can be established by
connecting TB1-2 to TB1-1, 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
2-12 BHK-1/2-MG SERIES 030916
between terminals TB1-5 (GND NET) and TB1-6 (+S). To disconnect the grounding network
from the output, remove the connection across TB1-5 and TB1-6 (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 TB1-3 (–S). To avoid
degraded load regulation in current mode it is necessary to remove the grounding network from
the circuit by removing the link between TB1-6 (+S) and TB1-5 (GND NET).
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 TB1-6 (+S). Note that when the positive output is grounded, the ground network (TB1-5) is
inoperative (see Figure 2-5).
FIGURE 2-5. REMOTE SENSING, FAST MODE SELECTED, POSITIVE OUTPUT GROUNDED
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.
BHK-1/2-MG SERIES 030916 2-13
LOCATION JUMPER
TABLE 2-9. INTERNAL JUMPER CONFIGURATION
DEFAULT
STATUS
FUNCTION
A1 J6 Not Installed For Service Personnel only. When installed (short circuit) a first time calibration
A2 JP1 Installed Enables input circuit breaker to trip when arcing at the output is detected.
A3 JP1 Installed
between pin
1 and 2
JP2 Installed Enables input circuit breaker to trip when input power loss is detected.
will be initiated. Use this jumper only when necessary, then remove the jumper
after calibration is initiated.
Jumper installed between pins 1 and 2: Prepares unit to receive a Relay N. (normally) Open Contact between pins 1 and 2 of the Status and Remote On/Off Port.
When contact is open unit is turned ON; when contact is closed, unit is turned
OFF.
Jumper installed between pins 2 and 3: Prepares unit to receive a Relay N. (normally) Closed Contact between pins 1 and 3 of the Status and Remote On/Off
Port. When contact is closed unit is turned ON; when contact is open, unit is
turned OFF.
2.9 STATUS PORT
The status port opto-coupler can be configured for either active “low” (see Figure 2-6) or active
“high” (see Figure 2-7).
FIGURE 2-6. STATUS PORT OPTO-COUPLER ACTIVE “LOW” CONFIGURATION
FIGURE 2-7. STATUS PORT OPTO-COUPLER ACTIVE “HIGH” CONFIGURATION
2-14 BHK-1/2-MG SERIES 030916
SECTION 3 - OPERATION
3.1 GENERAL
This section explains how to operate the BHK-MG 40W Power Supply. The power supply can be
operated either in Local mode using the front panel keypad and LCD (PAR. 3.2), or in Remote
mode using SCPI commands via either the GPIB bus (PARs. 3.3, 3.7) or RS 232 bus (PAR. 3.5)
or using analog programming via the rear panel terminals (PAR 3.8). Remote analog programming can be combined with either local programming using the front panel keyboard or remote
programming using SCPI commands via either the GPIB or RS 232 bus.
3.2 LOCAL MODE OPERATION
Local operation of the BHK-MG 40W 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-1/2-MG 030916 3-1
TABLE 3-1. LCD MESSAGES
LOCATION MESSAGE DESCRIPTION
Top left Loc/Rem Digital control status: either Remote or Local
Top middle SINK
top right OFF/CV/CC Off/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 (=_=_=).
Shows that the unit is in sink mode and is absorbing energy either
from the load or the internal output capacitor. The sink current is
model-dependent and appears on the second line of the display preceded by a minus (–) sign.
Minus sign Indicates current absorbed either from the load or discharge of the internal output capacitor.
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 SUPPLY
STATUS ACTIVE
Command Entry
TABLE 3-2. KEY FUNCTIONS
DESCRIPTION
If top line of LCD reads OFF, press to enable the output. If output is on,
press to disable the output controlled.
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 to 1.1 x nominal value.
REFERENCE
PARAGRAPH
3.2.7
3.2.9
3.2.9
3.2.4, B.82
3.2.8
3-2 BHK-1/2-MG 030916
TABLE 3-2. KEY FUNCTIONS (CONTINUED)
KEY
MENU Command Entry
OV SET
7
OC SET
8
CALIB
9
STORE Command Entry
EDIT
PROG
STEP
4
POWER SUPPLY
STATUS ACTIVE
Command Entry
Data Entry
Command Entry
Data Entry
Command Entry
Data Entry
Command 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) Go to Previous calibration, (10) Go to Factory Calibration, (11) view firmware version number ,
(12) set Power-up and RESET current, (13) set maximum voltage, (14)
set maximum current. 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
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
REFERENCE
PARAGRAPH
(1) 3.2.5, (2) 3.3.3
(3) 3.5.1, (4) 3.5.4
(5) 3.3.2,
(6) 3.2.7.4
(7,)3.2.6, (8) 4.6,
(9) 4.7, (10) 4.8
(11) 3.2.14
(10) 3.2.8.1
(11, 12) 3.2.11
3.2.10
3.2.10
4.3
3.2.12
3.2.15.1
3.2.15.3
TIME
5
RUN
6
RECALL Command Entry
CLEAR Data Entry
1 D ata Entry
2 D ata Entry
3 D ata Entry
ENTER Data Entry
BHK-1/2-MG 030916 3-3
Command Entry
Data Entry
Command Entry
Data Entry
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. 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
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
3.2.15.1.1
3.2.15.2
3.2.13
3.2.9
TABLE 3-2. KEY FUNCTIONS (CONTINUED)
KEY
0 Data Entry
( . ) Data Entry
POWER SUPPLY
STATUS ACTIVE
Command Entry
Data Entry
Command Entry
Data Entry
— 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).
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
Increases value shown (e.g. Display Contrast setting). 3.2.9
3.2.2 TURNING THE POWER SUPPLY ON
DESCRIPTION
REFERENCE
PARAGRAPH
3.2.9, 3.2.15.1
3.2.9
3.2.9, 3.2.15.1
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 circuit 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 500-80MG 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-1/2-MG 030916
3.2.3 ERROR CONDITIONS
Loc OFF
0.000A0.000V (:_:_:)
NOTE: (:_:_:) indicates blinking colon (:), Command Entry status
(=_=_=) indicates blinking equal sign (=), Data Entry status
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)
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 STATES
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-1/2-MG 030916 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.82), 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 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
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 references are disabled; 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.
NOTE: After disabling the o utput by pressing the OUTPUT ON/OFF key, if the analog input is
causing more than 8Vd-c to appear at the output terminals, or if current exceeds two
LSBs, the unit will beep and enter a controlled shutdown for safety purposes. The bottom line will flash a message showing the time remaining before shutdown (e.g POWER
OFF 9 SEC). After the 10 second countdown the front panel circuit breaker will trip. (If
the unit does not shut down due to a defective protection circuit or faulty circuit breaker,
the LCD displays **BHK** **FAILURE ** and beeps constantly.) This feature is not
available if the output is disabled via the Status and Remote On/Off Port.
3.2.7.2 DISABLING DC OUTPUT USING REMOTE ON/OFF PORT
The output can also be Enabled and Disabled by using the inputs available at the Status and
Remote On/Off port at the rear panel. Output on/off control can be obtained using either a normally-open relay contact, a normally-closed relay contact, or a TTL type signal. Controlling the
output through the Status and Remote On/Off Port is similar to using the OUTPUT ON/OFF
or the SCPI OUTPut ON and OUTPut OFF commands. Refer to Table 1-2 for characteristics of
Status and Remote On/Off Port signals and to Table 2-3 for pin assignments and functional
description.
key
3-6 BHK-1/2-MG 030916
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 o utput: output is disa bled and volt age and cu rrent are
set to zero (1 LSB maximum for voltage, 20 LSBs maximum for current). The DCL Control setting (see PAR. 3.3.2) determines the output settings when the output is enabled: either restored
to the voltage/current settings in effect at the time shut do wn wa s initiated , or volt ag e and current
still programmed to zero
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.
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 MENU key to
leave the value unchanged. Press number keys and the decimal key 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 = I
8.0mA). The unit remains in data entry status (=_=_=) waiting for a value equal to or less than
the 10% of rated current.
max/10 (e.g., for BHK500-80MG, xx =
O
BHK-1/2-MG 030916 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: Two decimal places are used for voltage settings and three decimal places for current
settings (except that only one decimal place is used for setting voltage on Models BHK
1000-40MG and BHK 2000-20MG).
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.3.2.11). Press CLEAR and
enter a value that does not exceed the maximum setting.
3.2.10 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 pr essed. 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.
The value for overvoltage protection can be set within the range of 0 to 1.1 x E
rent 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: Two decimal places are used for voltage settings and three decimal places for current
settings (except that only one decimal place is used for setting voltage on Models BHK
1000-40MG and BHK 2000-20MG).
max; overcur-
O
3-8 BHK-1/2-MG 030916
3.2.11 CHANGING MAXIMUM VOLTAGE OR CURRENT VALUE
The default maximum values of voltage and current are determined by the model, e.g., 500V
and 80mA for the BHK 500-80MG. 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 . Lowe ring the maximum va lues of the BHK 5 00-80MG to 100 V and 40mA, effectively
makes the unit a 100V/40mA power supply.
With the power supply in command 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 or
press ENTER to validate existing value. 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: Two decimal places are used for voltage settings and three decimal places for current
settings (except that only one decimal place is used for setting voltage on Models BHK
1000-40MG and BHK 2000-20MG).
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.
max or IOmax is the
O
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 current).
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.
3.2.12 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.
3.2.15).
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 existing location or 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. 3.2.13.
The default value at power-up for the Store command is 01. During normal operation, the location last used is displayed.
BHK-1/2-MG 030916 3-9
3.2.13 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. Press CLEAR to exit without changing setting. Press ENTER to validate existing location, or 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 v alue at power-up for the Recall
command is 01. During normal operation, the location last used is displayed.
3.2.14 FIRMWARE VERSION
To display the firmware version of the power supply, the power supply must be in command
entry status (:_:_:). Press the MENU key 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
1000-40MG), 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 an d return
to command entry status.
3.2.15 LOCAL MODE PROGRAMMING OF THE POWER SUPPLY.
Local mode programming offers the user 4 0 memory loc ation s that can b e used to pr ogram 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.
3.2.15.1 CREATING OR MODIFYING A PROGRAM (PROGRAM EDIT MODE)
Creating a program and modifying an existing program are identica l except that a pr ogram 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.
The factory default values for all memory locations is: 0 V olt s, 0 Amperes, Over voltag e set to 1.1
x E
max, Overcurrent set to 1.1 x IOmax, time duration set to 0.01 Sec and Next Step is set to
O
0.
The top line of the LCD indicates the active memory location, e.g. ViewVAL Mem <n> where n
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.3.2.15.1.1.
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. 3.2.15.5; to cyc le a
program continuously, see 3.2.15.4. 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 3-4) and filling in the values before programming the power
supply.
3-10 BHK-1/2-MG 030916
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-1/2-MG 030916 3-11
3.2.15.1.1 MODIFYING PROGRAMMED TIME INTERVAL
WARNING
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 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 (:_:_:).
Refer to PAR. 3.2.15.1.2 if accuracy of time values is important.
3.2.15.1.2 TIME INTERVAL ACCURACY
The accuracy of the time interval is ±1% through the entire time interval range.
3.2.15.2 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***.
3.2.15.3 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.
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).
3-12 BHK-1/2-MG 030916
3.2.15.4 CYCLING A PROGRAM
To cycle a program, modify the program (see PAR. 3.2.15.1) and go to the last memory location
to be executed and set the NEXT STEP address 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.
3.2.15.5 RUNNING A PROGRAM ONCE
To set up a program to stop after running once, modify the program (see PAR. 3.2.15.1) 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).
3.2.15.6 STOPPING A RUNNING PROGRAM
There are three ways to stop a program that is running:
• Press CLEAR key: the program stops after finishing the step (location) that 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.
3.2.15.7 SAMPLE PROGRAM
Ta ble 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.
TABLE 3-5. SAMPLE PROGRAM (MODEL BHK-MG 500-80MG)
MEMORY
LOCATION
1 40 420 44 550 1.5 02
2 40 500 44 550 1.8 03
3 40 250 44 550 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)
3.2.16 CALIBRATION
See Section 4.
BHK-1/2-MG 030916 3-13
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 provide s a common languag e conforming to IEEE
488.2 for instruments used in an automatic test system. The control bus used must be either the
IEEE 488 standard communication bus (General Purpose Interface Bus, GPIB). or the RS 232
Serial Bus described in PAR. 3.5. Refer to Table 2-1 for input/output signal allocations.) Most
power supply functions available from the keyp ad can be programmed vi a remote command s, 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. 3.4), followed by a detailed explanation of SCPI
programming (PAR. 3.7)
3.3.1 IEEE 488 (GPIB) BUS PROTOCOL
Table 3-6 defines the interface capabilities of the BHK-MG 40W Power Supply (Talker/Listener)
relative to the IEEE 488 (GPIB) bus (reference document ANSI/IEEE Std 488: IEEE S t andard Digi-
tal 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
40W 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
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.
SUBSET
SYMBOL
Basic talker, serial poll, unaddress if MLA (My Listen Address) (one-byte
address)
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.82) 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
Controller C0 No Capability
3-14 BHK-1/2-MG 030916
TABLE 3-7. IEEE 488 (GPIB) BUS COMMAND MODE MESSAGES
MNEMONIC
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
MESSAGE
DESCRIPTION
COMMENTS
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.
Data Byte Received or Sent
End Received or Sent
End of String Received or Sent
Request Service Sent
Status Byte Sent
BHK-1/2-MG 030916 3-15
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 1 again for “output = 0” mode where DCL sets the output to 0 volt s and curre nt
is set to the power-up and reset current value (see PAR. 3.2.8.1).
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 displays GPIB addr. = nn where nn 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, applyin g a tem porary 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.56) and CURR:TRIG (PAR B.46) commands.
• Choose external trigger source by sending TRIG:SOUR EXT (PAR. B.90)
• 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 PROGRAMMING TECHNIQUES TO OPTIMIZE PERFORMANCE
3.3.5.1 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 enters the mode of operation, constant voltage (CV) or constant current (CC)
determined by the power supply settings and load value. Reducing the number of times that the
unit changes mode from CV to CC or from CC to CV is desirable because Kepco's digital autocrossover supplies employ two separate fee dback loops. Each time there is a potential mode
change, there is always an uncontrolled period of time while the two feedback loops compete for
control of the output. By changing only the active parameter (e.g., voltage for volt age mode) an d
leaving the inactive parameter (e.g., current in this case) set to a value higher than the maximum imposed by the load, the response is quick and no transients are possible. Recommended
programming techniques are:
3-16 BHK-1/2-MG 030916
1. Minimize programmed mode (voltage or curre nt) change s. Unle ss abso lutely 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.
2. For MAT/MBT units only, once the mode (voltage or current) is chosen and program med,
program the active parameter to zero and the complementary limit parameter to the maximum anticipated for the 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. Never program both the active and complementary limit parameters to zero. This can result
in long response times. With this in mind, avoid using *RST unless absolutely necessary
(e.g., at the end of a program, or for an emergency) . Set the active p arameter to zero a nd the
complementary limit parameter to minimum, e.g., 1% of maximum, to ensure that the active
mode is defined.
4. For units with relays (e.g., MAT/MBT/MST) avoid sending OUTP ON and OUTP OFF unnecessarily to reduce wear and tear and extend the life of the relays.
3.3.5.2 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
• DISP:CONT
• 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.75) 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.
BHK-1/2-MG 030916 3-17
#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”);
}
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.
FIGURE 3-2. PROGRAMMING EXAMPLE TO VERIFY PREVIOUS COMMAND HAS COMPLETED
3.4 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
3-18 BHK-1/2-MG 030916
manual which can be used to program one or more BHK-MG power supplies using a vir tual 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 16-bit VISA driv er from your G PIB card supplier. Many vendors supply
this software with the hardware; National Instruments (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.
3.5 RS232-C OPERATION
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 llow s:
• Baud rate: 9600 (no jumper between RTS and CTS on RS 232 port)
• Parity: None
•Data Bits8
• Stop Bits 1
• Echo ON
• XON OFF
3.5.1 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.
3.5.2 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 Carria ge Return. The serial interface supports
three 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.
3.5.3 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
BHK-1/2-MG 030916 3-19
originator (computer) and the BHK-MG 40W 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 controller must ver ify th at ea ch
character is echoed back by the BHK-MG. As sho wn 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.
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).
3.5.3.1 ECHO MODE
Echo mode is the default method of ensuring dat a is transferred witho ut errors. Each byte (character) is echoed back to the sender where it is verified as the same character that was just sent.
If the character is incorrect or missing, the sender sends the character again until the correct
character is verified as having been received.
FIGURE 3-3. RS 232 IMPLEMENTATION
)
H
)
H
)
H
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).
3-20 BHK-1/2-MG 030916
3.5.3.2 PROMPT METHOD
The command originator sends a message line (command) to the BHK-MG and waits until the
prompt sequence CR LF > (3E
, 6210) is received. The BHK-MG sends the prompt sequence
H
CR LF > to the command or iginator indicating the power supply is ready to receive the next
command and data will not be lost. The prompt method is similar to the echo method described
above, except that the command originator does not have to compare each character and
repeat any characters dropped while the IEEE 1118 bus (BITBUS) is active. The operation of
the BHK-MG is identical for echo mode and prompt mode; implementation of prompt mode is at
the command originator.
3.5.3.3 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 dat a afte r the XON (transmission on) character (011
XOFF (transmission off) character (013
) has been received; the command originator stops sending data after receiving the
H
), and waits until the XON character is received before
H
sending additional data.
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).
3.5.4 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.
BHK-1/2-MG 030916 3-21
3.6 PROGRAMMING TECHNIQUES TO OPTIMIZE PERFORMANCE
Proper programming techniques can offer significant response time improvement and reduce
undesirable transients at the output. The key to performance optimization is to minimize mode
changes (voltage mode/current limit to current mode/voltage limit or vice versa). Mode changes
should be limited to changes in load conditions (to which the power supply will respond automatically), or by programming the limit parameter when required by the user application.
The proper way to program the supply is to initially program the operating parame ter to zero and
the complementary limit parameter to the desired maximum value. Subsequent commands
should change only the operating parameter. (The operating parameter is the parameter that
controls the output, e.g., voltage controls the output in voltage mode, current in current mode.)
The complementary limit parameter should be programmed only when there is a need to
change it.
3.6.1 EXAMPLE OF PROPER PROGRAMMING
Assume the power supply is intended to operate in a test application that requires a set of specific output voltages. The initial set of commands should program output voltage and current
limit. If the same current limit applies to the rest of the test, all subsequent commands should
only program output voltage.
3.6.2 EXPLANATION OF PROGRAMMING TECHNIQUES
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. In addition to increasing the time before the output reflects the programmed command, undesirable transients may also be present at the output during this
period.
By sending only the operating command, 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.
3.7 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 S tandard Codes, Formats, Protocols, and Common Commands). SCPI commands are sent to the BHK-MG 40W Power Supply a s ASCII output stri ngs 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 programming language used. Address inf ormation (GPIB address) must be included before the command sequence. (See PAR.3.3.3 to
establish the BHK-MG 40W Power Supply GPIB address.)
3-22 BHK-1/2-MG 030916
3.7.1 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
formatted data; the data can contain information regarding operating parameters, power supply
state, status, or error conditions.
3.7.2 COMMON COMMANDS/QUERIES
Common commands and queries are defined by the IEEE 488.2 standard to perform overall
power supply functions (such as id entification, status, or synchronization) un related 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 3.7.3 through 3.7.6).
3.7.3 SCPI SUBSYSTEM COMMAND/QUERY STRUCTURE
Subsystem commands/queries ar e related to specific power supply functions (such as setting
output voltage, current limit, etc.) Figure 3-4 is a tree diagram illustrating the structure of SCPI
subsystem commands used in the BHK-MG 40W Power 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.
3.7.3.1 ABORT SUBSYSTEM
This subsystem allows pending trigger levels to be cancelled.
3.7.3.2 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.
3.7.3.3 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.
3.7.3.4 MEASURE SUBSYSTEM
This query subsystem returns the voltage and current measured at the power supply's output
terminals.
3.7.3.5 OUTPUT SUBSYSTEM
This subsystem controls the power supply's voltage and current outputs
BHK-1/2-MG 030916 3-23
3.7.3.6 INSTRUMENT SUBSYSTEM
This subsystem controls the power supply's voltage and current outputs and allows compatibility
with other vendor’s products
3.7.3.7 STATUS SUBSYSTEM
This subsystem programs the power supply status register. The power supply has two group s of
status registers: Operation and Questionable. Each group consist s of thr ee register s: Cond ition,
Enable, and Event.
3.7.3.8 SYSTEM SUBSYSTEM
This subsystem controls the RS 232 port, as well as system errors, passwords, security, language, beep, version and keyboard lockout
3.7.3.9 TRIGGER SUBSYSTEM
This subsystem controls the remote triggering of the power supply.
3.7.3.10 [SOURCE:]VOLTAGE AND [SOURCE:]CURRENT SUBSYSTEMS
These subsystems program the output voltage and current of the power supply.
3.7.3.11 CALIBRATE SUBSYSTEM
The BHK-MG series of power supplies supp ort so f 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 commands th rough the GPIB bu s. 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 then 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, current readback and 10
percent scale current readback are calibrated. The normal procedure is to calibrate voltage first
and then current. However, you do not have to do a complete calibration each time. If required,
you may calibrate only the voltage or the current and then proceed to saving the calibration
results. For voltage calibration 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.
3-24 BHK-1/2-MG 030916
ABORt subsystem
ABORt
INITiate subsystem
INITiate
[:IMMediate]
:CONTinuous bool
:CONTinuous?
CALibrate subsystem
CALibrate
:STATe <boolean> ,password
:STATe?
:VOLTage
:LEVel (MIN | MAX | PROT)
[:DATA] val
GAIN (UP | DOWN)
:CURRent
:LEVel (MIN | MAX | MAG | PROT)
[:DATA] val
:ZERO
:SAVE
:COPY
:DUMP
:RESTore
MEASure subsystem
MEASure
[:SCALar]:CURRent[:DC]?
[:SCALar]:[VOLTage][:DC]?
OUTPut subsystem
OUTPut
[:STATe] ON | OFF or 0 | 1
[:STATe]?
DISPlay subsystem
DISPlay
:CONTrast 0.0 to 0.9
:CONTrast ?
:MODE
:MODE?
:TEXT
:TEXT?
ROOT : (colon)
STATus subsystem
STATus
:OPERation
:CONDition?
:ENABle val
:ENABle?
[:EVENt]?
:PRESet
:QUEStionable
:CONDition?
:ENABle val
:ENABle?
[:EVENt]?
SYSTem subsystem
SYSTem
:BEEP
:COMM
:SER
:BAUD val
:BAUD?
:ECHO
:ECHO? ON, OFF
:PACE
:PACE? NONE, XON
:PROMpt
:PROMpt? ON, OFF
:GPIB:ADDR val
:GPIB:ADDR?
:ERRor
[:NEXT]?
:CODE?
[:NEXT]?
:ALL?
:GPIB:ADDR val
:GPIB:ADDR?
:KLOCk <boolean>
:KLOCk?
:PASSword
[:CENAble] (code)
:STATe?
:CDISenable (code)
:NEW (OLD | NEW)
:SECUrity
:IMMediate
:VERSion?
INSTRument subsystem
INSTrument
:STATe?
:STATe (ON | OFF)
[SOURce:] subsystem
[SOURce:]
CURRent
[:LEVel]
[:IMMediate]
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:TRIGgered
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:LIMit
[:HIGH] val
[:HIGH]? MIN, MAX
:MODE LIST, FIX
:PROTection val
VOLTage
[:LEVel]
[:IMMediate]
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:TRIGgered
[:AMPLitude] val
[:AMPLitude]? MIN, MAX
:LIMit
[:HIGH] val
[:HIGH]? MIN, MAX
:MODE LIST, FIX
:PROTection val
FUNCtion
:MODE VOLTage CURRent
:MODE?
LIST subsystem
LIST
:CLE
:COUNT val
:COUN?
:COUN:SKIP val
:COUN:SKIP?
:CURRent
[:LEVel] val
[:LEVel]?
:POINter?
:DIR val
:DIR?
:DWELl val
:DWELl?
:POINter?
:DWELl
:QUERy val
:QUERy?
:VOLTage
[:LEVel] val
[:LEVel]?
:POINter?
TRIGGER subsystem
TRIGger
:SOURce
See PAR. 3.3.5.2 and Figure 3-2 for
special programming consider ations.
FIGURE 3-4. TREE DIAGRAM OF SCPI COMMANDS USED WITH BHK-MG 40W POWER SUPPLY
BHK-1/2-MG 030916 3-25
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
3.7.4 PROGRAM MESSAGE STRUCTURE
SCPI program messages (comm ands from controller to power su pply) 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 separated 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 3-5 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-
3.7.4.1 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 3-4.
FIGURE 3-5. MESSAGE STRUCTURE
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.
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
3-26 BHK-1/2-MG 030916
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 3-9.
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).
3.7.4.2 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).
3.7.4.3 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?).
3.7.4.4 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
3.7.4.5 DATA SEPARATOR
Data must be separated from the last keyword by a space (e.g., VOLT:LEV:TRIG 14 or
SOUR:VOLT? MAX
3.7.4.6 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).
3.7.4.7 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 3-4) of the command tree. Note the difference
between using the colon as a keyword separator and a root specifier in the following examples:
BHK-1/2-MG 030916 3-27
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.
3.7.4.8 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 end 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.
3.7.5 UNDERSTANDING THE COMMAND STRUCTURE
Understanding the command structure requires an understanding of the subsystem command
tree illustrated in Figure 3-4. 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 40W 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 path
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;
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.
3-28 BHK-1/2-MG 030916
3.7.6 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 keyword
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
3.7.7 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 program using SCPI commands to program the BHK-MG 40W
Power Supply . The pr ogram 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.
BHK-1/2-MG 030916 3-29
/**************************************************************************/
/* 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 40W POWER SUPPLY PROGRAM USING SCPI COMMANDS
3.8 REMOTE PROGRAMMING USING ANALOG PROGRAMMING TERMINALS
The BHK-MG 40W Power Supply is designed with separate, but similar, circuits for analog volt-
3-30 BHK-1/2-MG 030916
age 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 mo de, or volt age
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.
FIGURE 3-7. ANALOG VOLTAGE PROGRAMMING, SIMPLIFIED DIAGRAM
FIGURE 3-8. ANALOG CURRENT PROGRAMMING, SIMPLIFIED DIAGRAM
BHK-1/2-MG 030916 3-31
For each circuit, the digital programming section provides a voltage (DP (V) for voltage, DP (C)
10 Eout
dp
–
10
Eomax
----------------------
V–
10 I out
dp
–
10
Iomax
--------------------
V–
for current), between zero and -10V d-c, applied to the input of a summing amplifier. This amplifier drives, in turn, the voltage error amplifier and the pass 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 sect ion at the input of the summing 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.
If digital programming is at zero, analog programming requires a voltage between zero and
–10V d-c to be applied to terminal 9 (TB2 for vo ltage, TB3 for curren t). If digital progr amming is
combined with analog programming, the voltage range for the signal applied to termin al 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 th e required volt age from a num ber 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 500-80MG 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 programmin g 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.
3-32 BHK-1/2-MG 030916
3.8.1 ANALOG PROGRAMMING WARNINGS AND CAUTIONS
WARNING
WARNING
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.
b. Use high voltage rated cables (at least 3kV) for all connections, even for programming
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 40W Pow er 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 terminal 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.
BHK-1/2-MG 030916 3-33
The following warnings and caut ions apply to the analog programming terminals because the
WARNING
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 .”
• If the power supply must operate isolate d fro m ground ( floating), a ny external equ ipment
connected to the ANALOG PROGRAMING TERM INALS must also be isolated (batter y
operated or connected to a-c source power using an isolating transformer).
Safety Message
When the output is disabled, whether by the OUTPUT ON/OFF key, SCPI command via GPIB
or RS 232 interface, or via the S t atus and Remote On/Of f Port, an internal solid-state switch sets
the voltage/current references to zero, resu lting in zero output from the power supply. In the
case of the OUTPUT ON/OFF key or SCPI command, if the solid state switch fails, and the output is higher than 8V, and the current is higher than 1mA, a shutdown sequence begins: the unit
beeps and flashes the message Power Down in XX sec for 10 seconds as XX counts down
from 10 to 0. After 10 seconds the input circuit breaker trips OFF. If the circuit breaker does not
trip OFF, BHK Failure is displayed on the LCD.
3.8.2 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.
3-34 BHK-1/2-MG 030916
FIGURE 3-9. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE)
OR VOLTAGE LIMIT (CURRENT MODE) USING RESISTANCE
For either voltage programming or curr ent programming, the external r esistor R
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 sum ming ne two rk at the inpu t of the
summing amplifier. For voltage programming, the other input to the summing amplifier, DP (V),
is from the voltage portion of the digital programming circuitry (either from the keypad or the
GPIB bus). For current programming, the other input to the summing 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 BHK 300-130MG BHK 500-80MG BHK 1000-40MG BHK 2000-0.02MB
Voltage Feedback Resistor R
(Ohms)
Current Sensing Resistor Rs
(Ohms)
* All resistors are 1% tolerance.
BHK-1/2-MG 030916 3-35
connected
EXT
300K* 500K* 1000K* 2000K*
0.008K* 0.0125K* 0.025K* 0.050K*
FIGURE 3-10. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE)
OR CURRENT LIMIT (VOLTAGE MODE) USING RESISTANCE
3.8.2.1 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 from 0 to E
The following equation gives the output voltage as determined by external resistance R
max with a slope of (0.0001 x EOmax) volts per ohm.
O
EXT
.
Eo = (–1) (10V) x (R
EXT
= (–1) (0.1 x R) x R
= –0.1R x R
EXT
(V d-c)
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 (K-ohms), determined by Model (see Table 3-10).
3-36 BHK-1/2-MG 030916
/10K) x (–1) (10K/10K) x (–1) (R/10K)
EXT
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. 3.8
3.8.2.2 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 I
following equation gives the output current as determined by external resistance R
max with a slope of (0.0001 x IOmax) mA per ohm. The
O
EXT
.
Io = [ (–1) (10V) x (R
= (–1) (0.1/ Rs) x R
= (–0.1/Rs) x R
/10K) x (–1) (10K/10K) x (–1/10) (10K/10K ) ]/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
EXT
.)
3.8.3 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 source) 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.
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-1/2-MG 030916 3-37
CAUTION
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-1/2-MG 030916
FIGURE 3-12. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING GROUNDED LOW IMPEDANCE VOLTAGE SOURCE (VS)
BHK-1/2-MG 030916 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-1/2-MG 030916
FIGURE 3-14. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT
LIMIT (VOLTAGE MODE) USING GROUNDED LOW IMPEDANCE VOLTAGE SOURCE (VS)
3.8.3.1 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 E
E
max) volts per volt. The following equations give the output voltage as determined by a low
O
impedance voltage source V
BHK-1/2-MG 030916 3-41
EXT
max with a slope of (0.1 x
O
.
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (–1) (V
= (–1) (0.1 x R) x V
= –0.1R x V
) x (10K/10K) x (–1) (10K/10K) x (–1) (R/10K)
EXT
EXT
(V d-c)
EXT
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
) – 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
3.8.3.2 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 I
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
.)
EXT
max with a slope of (0.1 x IOmax)
O
.
EXT
) x (10K/10K) x (–1) (10K/10K) x (–1/10) (10K/10K) ]/Rs
EXT
EXT
EXT
(mA d-c)
EXT
(mA d-c)
.)
EXT
– IoutDP (mA d-c)
Iout
= Output current programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of Rs and V
3.8.4 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 jump er configuratio n
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 volt-
3-42 BHK-1/2-MG 030916
EXT
.)
age 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.
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.
FIGURE 3-15. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING HIGH IMPEDANCE, LOW LEVEL (1V) VOLTAGE SOURCE (VS)
BHK-1/2-MG 030916 3-43
FIGURE 3-16. ANALOG PROGRAMMING OF OUTPUT CURRENT (CURRENT MODE) OR CURRENT
LIMIT (VOLTAGE MODE) USING HIGH IMPEDANCE, LOW LEVEL (1V) VOLTAGE SOURCE (VS)
3-44 BHK-1/2-MG 030916
3.8.4.1 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 linea rly from 0 to E
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 (K-ohms), determined by Model (see Table 3-10).
V
= E xternal low impedance voltage source ( Volts). This source can be either a d-c so urce
EXT
delivering a negative output voltage, or a function generator with an internal negative
bias. If the bias is not available from the function gener ator, 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)
max with a slope of (EOmax) volts per
O
where
Eout
= Output voltage programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of R and V
3.8.4.2 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 volt age source fr om 0 to –1V cau ses the output cu rrent of the power supply to vary linearly from 0 to I
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 ) (10K/10K) x (–1/10) (10K/10K) ]/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
.)
max with a slope of (IOmax) mA per volt.
O
where
Iout
= Output current programmed digitally (from either local keypad or remote GPIB bus)
DP
(See above for definitions of Rs and V
BHK-1/2-MG 030916 3-45
EXT
.)
3.8.5 PROGRAMMING WITH EXTERNAL CURRENT SOURCE (1 mA)
Figures 3-17 and 3-18 are simplified diagrams of the BHK-MG showing the jump er configuratio n
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 current 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-circuiting the internal sensing resistor.
FIGURE 3-17. ANALOG PROGRAMMING OF OUTPUT VOLTAGE (VOLTAGE MODE) OR VOLTAGE
LIMIT (CURRENT MODE) USING CURRENT SOURCE (1mA) (CS)
3-46 BHK-1/2-MG 030916
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-ci rcuiting the internal sensing resistor.
BHK-1/2-MG 030916 3-47
CAUTION
3.8.5.1 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 E
lowing equations give the output voltage as determined by the external current source I
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (–1)I
EXT
= –(R) x | I
where
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
I
= External current source (mA). This source can be either a d-c source or a function gen-
EXT
erator with an internal bias delivering a const a nt current. If the bia s 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
EXT
where
max with a slope of (EOmax) volts per mA. The fol-
O
x (10K) x (–1) (10K/10K) x (–1) (R/10K)
| (V d-c)
EXT
| ) – EoutDP (V d-c)
EXT
.
Eout
= Output voltage programmed digitally (fr om either local keypad or remote GPIB bus)
DP
(See above for definitions of R and V
3.8.5.2 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 I
lowing 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 I
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
max with a slope of (IOmax) mA per mA. The fol-
O
x (10K) x (–1) (10K/10K) x (–1/10) (10K/10K) ]/Rs
| (mA d-c)
EXT
.)
EXT
| – IoutDP (mA d-c)
EXT
.)
EXT
EXT
.
3-48 BHK-1/2-MG 030916
3.9 OPERATING MODES
This section describes the following operating modes for the BHK-MG 40W Power Supply
• Slow/Fast Mode
• Series Operation
• Automatic Series Operation
• Master-Slave Series Operation
• Parallel Operation
• Automatic Parallel Operation
• Master-Slave Parallel Operation
3.9.1 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 1 (-OUT.C) and terminal 2 (-OUT). This effectively increases the
main feedback capacitance by adding the internal feedback capacitor for slow mode C
fast mode capacitor C
(see Figure 3-19). When internal output capacitor C
FF
is across the
OUT
. to the
FS
output, 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 1 (-OUT.C) and terminal 2 (-OU T). This also
effectively 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
FS
and, in current mode, reduces the duration of transients caused by dynamic load changes; the
disadvantage 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 mode
applications when quick recovery time at load changes is desired.
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).
BHK-1/2-MG 030916 3-49
FIGURE 3-19. SLOW MODE/FAST MODE OPERATION
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 externa l output capacitor 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 TB1-1 and TB1-2. If the external cap acitor is comp ar able or larger than the internal C
the output by installing the link between terminals TB1-1 and TB1-2, 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.
3-50 BHK-1/2-MG 030916
, it is advisable to connect the internal C
OUT
CAUTION
OUT
OUT
across
3.9.2 SERIES OPERATION
WARNING
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. 3.9.2.1) and master-slave (PAR. 3.9.2.2).
HANDLING HIGH VOLTAGE, LOW IMPEDANCE EQUIPMENT IS DANGEROUS, AND
POTENTIALLY LETHAL. OBSERVE ALL PRECAUTIONS LISTED IN PAR. 3.8.1., 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 2000-20MG 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 Table 1-2).
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 information regarding 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 combination be grounded to avoid potentially hazardous conditions requiring the use of fully insulated external equipment (see precautions of PAR. 3.8.1).
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. 3.8.1).
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.
BHK-1/2-MG 030916 3-51
3.9.2.1 AUTOMATIC SERIES OPERATION
Vset Eo
EomaxA
EomaxA EomaxB+
--------------------------------------------------------------- -
=
This operating configuration (see Figure 3-20) is characterized by the fact that each power supply is independent and must be controlled (programmed) individually, 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 given by the following equations:
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 current limit of the o ther 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 assemb ly) is pr ope 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 un it to dis ab l e th e ou tp ut .
3. Program Unit A as follows:
NOTE: If using two different BHK models, e.g., 500-80MG and 1000-40MG, unit A must be the
one with the lower current capacity: 1000-40MG
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,
•E
maxA is the rated maximum output voltage for unit A (e.g. 500 for the BHK 500-
O
80MG),
•E
maxB is the rated maximum output voltage for unit B.
O
3-52 BHK-1/2-MG 030916
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.
BHK-1/2-MG 030916 3-53
FIGURE 3-20. SERIES AUTOMATIC CONFIGURATION
3-54 BHK-1/2-MG 030916
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