Fluke 5220A User Manual
5220A
®
Transconductance Amplifier
Instruction Manual
PN 491936
June 1979 Rev. 3, 6/97
© 1997 Fluke Corporation. All rights reserved. Printed in USA
All product names are trademarks of their r espective comp ani es.
LIMITED WARRANTY AND LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under
normal use and service. The warranty period is one year and begins on the date of shipment.
Parts, product repairs, and services are warranted for 90 days. This warranty extends only to the
original buyer or end-user customer of a Fluke authorized reseller, and does not apply to fuses,
disposable batteries, or to any product which, in Fluke’s opinion, has been misused, altered,
neglected, contaminated, or damaged by accident or abnormal conditions of operation or
handling. Fluke warrants that software will operate substantially in accordance with its functional
specifications for 90 days and that it has been properly recorded on non-defective media. Fluke
does not warrant that software will be error free or operate without interruption.
Fluke authorized resellers shall extend this warranty on new and unused products to end-user
customers only but have no authority to extend a greater or different warranty on behalf of Fluke.
Warranty support is available only if product is purchased through a Fluke authorized sales outlet
or Buyer has paid the applicable international price. Fluke reserves the right to invoice Buyer for
importation costs of repair/replacement parts when product purchased in one country is submitted
for repair in another country.
Fluke’s warranty obligation is limited, at Fluke’s option, to refund of the purchase price, free of
charge repair, or replacement of a defective product which is returned to a Fluke authorized
service center within the warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the
difficulty, postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in
transit. Following warranty repair, the product will be returned to Buyer, transportation prepaid
(FOB Destination). If Fluke determines that failure was caused by neglect, misuse, contamination,
alteration, accident, or abnormal condition of operation or handling, including overvoltage failures
caused by use outside the product’s specified rating, or normal wear and tear of mechanical
components, Fluke will provide an estimate of repair costs and obtain authorization before
commencing the work. Following repair, the product will be returned to the Buyer transportation
prepaid and the Buyer will be billed for the repair and return transportation charges (FOB
Shipping Point).
THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, ARISING FROM
ANY CAUSE OR THEORY.
Since some countries or states do not allow limitation of the term of an implied warranty, or
exclusion or limitation of incidental or consequential damages, the limitations and exclusions of
this warranty may not apply to every buyer. If any provision of this Warranty is held invalid or
unenforceable by a court or other decision-maker of competent jurisdiction, such holding will not
affect the validity or enforceability of any other provision.
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
11/99
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
Table of Contents
Section Title Page
1 Introduction and Specifications ........................................................ 1-1
1-1. Introduction.......................................................................................... 1-1
1-2. Specifications ....................................................................................... 1-2
2 Operating Instructions....................................................................... 2-1
2-1. Introduction.......................................................................................... 2-1
2-2. Shipping Information............................................................................ 2-1
2-3. Input Power .......................................................................................... 2-1
2-4. Fuse Replacement................................................................................. 2-2
2-5. AC Line Fuse................................................................................... 2-2
2-6. Power Supply Fuses......................................................................... 2-2
2-7. Rack Installation................................................................................... 2-2
2-8. Operating Features................................................................................ 2-2
2-9. Operating Notes.................................................................................... 2-5
2-10. AC Line Connection ........................................................................ 2-5
2-11. Transconductance Amplifier............................................................ 2-5
2-12. Input Voltage Requirements ............................................................ 2-5
2-13. Input Voltage Selection, Front/Rear ................................................ 2-6
2-14. Current Output, Front/Rear.............................................................. 2-6
2-15. Standby/Operate............................................................................... 2-6
2-16. Local/Remote................................................................................... 2-6
2-17. Status Indicators............................................................................... 2-6
2-18. Audible Output................................................................................. 2-7
2-19. Inductive Loads................................................................................ 2-7
2-20. Operation.............................................................................................. 2-9
3 Theory of Operation........................................................................... 3-1
3-1. Introduction.......................................................................................... 3-1
3-2. Overall Functional Description ............................................................ 3-1
3-3. General............................................................................................. 3-1
3-4. Analog Section................................................................................. 3-1
3-5. Digital Section.................................................................................. 3-4
3-6. Circuit Analysis.................................................................................... 3-4
3-7. Power Supply................................................................................... 3-4
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Instruction Manual
3-8. Preamplifier...................................................................................... 3-6
3-9. A6 Driver ......................................................................................... 3-7
3-10. A7 Output......................................................................................... 3-9
3-11. A8 Analog Control........................................................................... 3-10
3-12. A9 Front Panel................................................................................. 3-11
3-13. A10 Logic ........................................................................................ 3-11
3-14. Reset Logic.................................................................................. 3-11
3-15. Timing Logic............................................................................... 3-13
3-16. Standby/Operate Logic................................................................ 3-14
3-17. Local/Remote Logic .................................................................... 3-15
3-18. Front/Rear Input Logic................................................................ 3-15
3-19. Failure Status Logic..................................................................... 3-16
3-20. A11 MIS Bus Interface.................................................................... 3-16
4 Maintenance....................................................................................... 4-1
4-1. Introduction.......................................................................................... 4-1
4-2. Service Information.............................................................................. 4-2
4-3. General Maintenance............................................................................ 4-2
4-4. Cleaning........................................................................................... 4-2
4-5. Air Filter Maintenance..................................................................... 4-2
4-6. Access Information.......................................................................... 4-2
4-7. Internal Components/Assemblies................................................ 4-4
4-8. Front Panel Removal ................................................................... 4-4
4-9. A9 Front Panel PCB Removal..................................................... 4-4
4-10. A2 Transformer Assembly Removal........................................... 4-4
4-11. A6 Driver and A7 Output Assembly Removal............................ 4-5
4-12. A3 Cap Bus Removal .................................................................. 4-5
4-13. A12 Shunt Assembly Removal.................................................... 4-5
4-14. Fuse Replacement............................................................................ 4-6
4-15. Ac Line Fuse................................................................................ 4-6
4-16. Power Supply Fuses..................................................................... 4-6
4-17. Line Voltage Selection..................................................................... 4-6
4-18. Output Terminal Selection, Front/Rear............................................ 4-7
4-19. Service Tools.................................................................................... 4-8
4-20. Performance Test.................................................................................. 4-8
4-21. Initial Conditions.............................................................................. 4-8
4-22. Front Panel Tests.............................................................................. 4-9
4-23. Zero Output...................................................................................... 4-9
4-24. DC Accuracy and Line Regulation.................................................. 4-10
4-25. Harmonic Distortion......................................................................... 4-10
4-26. Frequency Response......................................................................... 4-11
4-27. Overcurrent Trip Test....................................................................... 4-11
4-28. Overvoltage Trip Test...................................................................... 4-12
4-29. Calibration Adjustments....................................................................... 4-12
4-30. Initial Conditions.............................................................................. 4-13
4-31. Input Offset Adjustment................................................................... 4-13
4-32. Driver Offset Adjustment................................................................. 4-13
4-33. Output Bias Adjustment................................................................... 4-14
4-34. DC Accuracy Adjustment................................................................ 4-14
4-35. Frequency Response......................................................................... 4-14
4-36. Overcurrent Adjustment................................................................... 4-15
4-37. Overvoltage Adjustment.................................................................. 4-15
4-38. Replacement of Selected Components................................................. 4-15
4-39. Resistors R11 and R12..................................................................... 4-16
ii
Contents
4-40. Resistor R13..................................................................................... 4-17
4-41. Troubleshooting.................................................................................... 4-18
5 List of Replaceable Parts................................................................... 5-1
5-1. Introduction.......................................................................................... 5-1
5-2. How to Obtain Parts............................................................................. 5-1
5-3. Manual Status Information................................................................... 5-2
5-4. Newer Instruments................................................................................ 5-2
5-5. Service Centers..................................................................................... 5-2
6 Option and Accessory Information................................................... 6-1
6-1. Introduction.......................................................................................... 6-1
6-2. Accessories........................................................................................... 6-1
6-3. Rack Mounting Kit (M08-205-600)................................................. 6-1
6-4. Rack Slide Kit (M00-280-610) ........................................................ 6-3
6-5. Precision Y5020A Current Shunt..................................................... 6-3
7 Schematic Diagrams.......................................................................... 7-1
(continued)
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5220A
Instruction Manual
iv
List of Tables
Table Title Page
1-1. Accessories ............................................................................................................ 1-2
1-2. Specifications......................................................................................................... 1-2
2-1. Controls, Indicators, and Connectors..................................................................... 2-4
3-1. Effect of Reset Command on A10 Logic and A9 Front Panel............................... 3-13
4-1. Required Test Equipm ent...................................................................................... 4-1
4-2. DC Accuracy Test.................................................................................................. 4-10
4-3. Frequency Response Test ...................................................................................... 4-11
4-4. Replacement Resistors for R11 and R12............................................................... 4-17
4-5. Replacement Resistors for R13.............................................................................. 4-18
4-6. Mainframe and Digital Section Troubleshooting Guide........................................ 4-21
4-7. Analog Section Troubleshooting Guide................................................................. 4-25
5-1. 5220A Final Assembly .......................................................................................... 5-4
5-2. A1 Motherboard PCB Assembly........................................................................... 5-17
5-3. A2 Power Transformer Assembly ......................................................................... 5-18
5-4. A3 Capacitor Bus PCB Assembly......................................................................... 5-19
5-5. A4 Regulator PCB Assembly................................................................................ 5-21
5-6. A5 Preamplifier PCB Assembly............................................................................ 5-23
5-7. A6 Driver PCB Assembly...................................................................................... 5-26
5-8. A7 Output PCB Assembly..................................................................................... 5-28
5-9. A8 Analog Control PCB Assembly....................................................................... 5-31
5-10. A9 Front Panel PCB Assembly.............................................................................. 5-33
5-11. A10 Logic PCB Assembly..................................................................................... 5-34
5-12. A11 MIS Bus Interface PCB Assembly................................................................. 5-36
5-13. A12 Shunt Assembly............................................................................................. 5-38
5-14. A13 Output Termination PCB Assembly.............................................................. 5-40
5-15. A14 Extender PCB Assembly................................................................................ 5-41
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5220A
Instruction Manual
vi
List of Figures
Figure Title Page
5220A Transconductance Amplifier...................................................................... x
1-1. Outline Drawings................................................................................................... 1-5
2-1. Controls, Indicators, and Connectors..................................................................... 2-3
2-2. Maximum Load Inductance vs Frequency............................................................. 2-8
2-3. Typical Transconductance Error for Inductive Loads........................................... 2-9
3-1. 5
3-2. Transconductance Amplifier Simplified Circuit Diagram..................................... 3-3
3-3. Power Supply Functional Block Diagram............................................................. 3-5
3-4. A5 Preamplifier Functional Block Diagram.......................................................... 3-6
3-5. A6 Driver Functional Block Diagram.................................................................... 3-8
3-6. A7 Output Functional Block Diagram................................................................... 3-9
3-7. A8 Analog Control Simplified Block Diagram ..................................................... 3-10
3-8. A10 Logic Simplified Block Diagram................................................................... 3-12
3-9. Timing Sequence ................................................................................................... 3-14
3-10. A11 MIS Bus Interface.......................................................................................... 3-18
4-1. Internal Component/Assembly Locations.............................................................. 4-3
4-2. Line Voltage Selec tion........................................................................................... 4-7
4-3. Test Point Location/Identification......................................................................... 4-19
4-4. Flowchart Summary of Mainframe and Digital Section Troubleshooting Guide.. 4-20
4-5. Flowchart Summary of Analog Section Troubleshooting Guide........................... 4-24
5-1. 5220A Final Assembly .......................................................................................... 5-8
5-2. A1 Motherboard PCB Assembly........................................................................... 5-17
5-3. A2 Power Transformer Assembly ......................................................................... 5-18
5-4. A3 Capacitor Bus PCB Assembly......................................................................... 5-20
5-5. A4 Regulator PCB Assembly................................................................................ 5-22
5-6. A5 Preamplifier PCB Assembly............................................................................ 5-25
5-7. A6 Driver PCB Assembly...................................................................................... 5-27
5-8. A7 Output PCB Assembly..................................................................................... 5-29
5-9. A8 Analog Control PCB Assembly....................................................................... 5-32
5-10. A9 Front Panel PCB Assembly.............................................................................. 5-33
5-11. A10 Logic PCB Assembly..................................................................................... 5-35
5-12. A11 MIS Bus PCB Assembly................................................................................ 5-37
5-13. A12 Shunt Assembly............................................................................................. 5-39
5-14. A13 Output Termination PCB............................................................................... 5-40
5-15. A14 Extender PCB Assembly................................................................................ 5-41
220A Functional Block Diagram......................................................................... 3-2
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5220A
Instruction Manual
6-1. Rack Mounting Kit ................................................................................................ 6-2
6-2. Rack Slide Kit........................................................................................................ 6-4
7-1. Interconnect Diagram............................................................................................. 7-2
7-2. Chassis Wiring....................................................................................................... 7-4
7-3. Power Supply......................................................................................................... 7-6
7-4. A5 Preamplifier PCB Assembly............................................................................ 7-8
7-5. A6 Driver and A7 Output PCB Assemblies .......................................................... 7-10
7-6. A8 Analog Control PCB Assembly....................................................................... 7-12
7-7. A9 Front Panel PCB Assembly.............................................................................. 7-14
7-8. A10 Logic PCB Assembly..................................................................................... 7-16
7-9. A11 MIS Bus Interface PCB Assembly................................................................. 7-18
viii
Contents
(continued)
ix
5220A
Instruction Manual
5220A Transconductance Amplifier
x
ajs36f.eps
Introduction and Specifications
1-1. Introduction
The Model 5220A is a transconductance amplifier designed to operate as either a stand
alone unit or an extension of the Fluke Model 5100 Series Calibrator. Functionally, the
instrument operates as a precision ac/dc current source for calibrating current shunts
and/or current meters. As the name (trans condu cta nce amp l if ier ) impli es, the output
current level is a function of an input control voltage. The input/output ratio is established
at 1:1 so that a voltage input in the range of -20 to +20 volts will produce a proportional
current output of -20 to +20 amperes. Input voltages may be either dc or ac levels,
depending on the output requirements. Bandwidth for ac operation is dc to 5 kHz.
Control of the 5220A can be handled locally using front panel controls or remotely by
way of the 5100 Series Calibrator. (The 5100 must be equipped with a Model Y5000
Interface.) Control mode selection is accomplished using two front-panel push button
switches, INPUT and LOCAL. The INPUT switch allows selection of either front or rear
control-voltage input connections. The LOCAL switch is used to recall the 5220A from
remote to local operation.
Section 1
A series of front panel indicators are used to visually display both the control and
operating status of the 5220A. Control indicators include OPER (operate), STDBY
(standby), FRONT input, REAR input, REMOTE, and LOCAL LOCKOUT. The
combination of lit LEDs indicates the present status of the control mode. Status indicators
include THERMAL CUT-OFF, OVER COMPLIANCE, and OVER CURRENT. When
any one of these indicators is lit, an overload condition has been detected causing the
5220A to switch to standby operation. All indicators are active regardless of the selected
control mode, local or remote.
Current output connections are provided on both the front and rear panels. However, only
one set of terminals is active. Selection of the desired set is accomplished internally and
is, therefore, not considered an operator fun ction. Neit her loc al nor re mot e opera tion is
affected by the selection of front or rear output.
Forced-air circulation is incorporated in the 5220A to ensure adequate cooling of the
current output stage. Air is pulled in through a rear-panel filter, passed over the output
stage heat sink, and exhausted through the unit’s side panels.
The 5220A is designed to operate from ac line voltages within the range of 90 V ac to
264 V ac, 50 to 60 Hz. One-of-eight specific voltages (100, 110, 115, 120, 200, 220, 230,
240 V ac +10 %) can be selected to ensure compatibility with the local line voltage. The
1-1
5 2 20A
Instruction Manual
1-2. Specifications
selection switches are inside the 5220A. Refer to Section 4 of this manual for information
on how to properly set the line power switches.
Accessories available for use with the 5220A are listed and described in Table 1-1. The
rack mounting kits are designed for use with a standard 19-inch equipment rack. The
Model Y5020A is a precision current shunt recommen ded for use in calibr at ing the
5220A. Specify both model number and description when ordering accessories.
Table 1-1. Accessories
Model No. Description
M07-205-600 Rack Mounting Kit
M00-260-610 Rack Slide Kit, 18 in
M00-280-610 Rack Slide Kit, 24 in
Y5020 Precision Shunt
Specifications for the Model 5220A are given in Table 1-2.
Table. 1-2. Specifications
Calibration Cycle All specifications are valid for a 180-day period at an operating
temperature of 20 °C to 30 °C and a relative humidity of 70 % or
less.
Basic
Transconductance 1 Siemen (1 ampere per volt)
Output Range 0 A to 20 A dc or rms ac (28.3 A peak)
Compliance Voltage ≥±4 V dc or 3 V rms ac (4.25 V peak)
DC Accuracy ±(0.025 % of output +1 mA)
AC Accuracy ±(0.05 % of output + 1 mA) from 30 Hz to 1 kHz, and ±(0.05 % of
output + 1 mA) x f from 1 kHz to 5 kHz, where f = frequency in kHz.
Short Term DC Stability Output changes less than ±(0.005 % + 200 µA) in 10 minutes, with
constant line, load, and temperature.
Short Term AC Stability Output changes less than ±(0.01 % + 500 µA) in 10 minutes, with
constant line, load, and temperature.
Harmonic Distortion and Noise ±(0.05 % of output ±1 mA rms) over frequency range of 30 Hz to 1
kHz and measured with a noise bandwidth of 300 kHz, ±(0.05 % of
output + 1 mA) x f from 1 kHz to 5 kHz, where f = frequency in kHz.
Temperature Coefficient ±(0.0025 % of output + 100 µA) per degree C above 30 °C or
below 20 °C.
1-2
Transient Recovery Output will settle to within 0.01 % of final value within 2 seconds
following a programmed change in output current or frequency
(10 ms for 5220A alone).
Introduction and Specifications
Table 1-2. Specifications (cont.)
Electromagnetic Compatibility This instrument is designed to operate in Standard Laboratory
environments where in electromagnetic environment is highly
controlled. If used in areas with RF fields >0.4 V/m there could be
errors in measurement.
DC Mode (including 5100 Series B)
Output Range ±1 to ±19.9999 A
Accuracy of Output ±(0.025 % of selected output + 1 mA)
Resolution ±0.1 mA
Temperature Coefficient ±(0.003 % of selected output + 100 µA) / °C, above 30 °C and
below 20 °C
Line Regulation Output changes less than 0.001 % for a ±10 % change in line
voltage.
Load Regulation Output changes less than ±(0.005 % + 0.3 mA) for a full load
changes of 4 V of compliance.
AC Mode (including 5100 Series B)
Specifications
1
Output Range 1 A rms to 19.9999 A rms
Accuracy of Output ±(0.07 % of selected output + 1 mA rms) from 50 Hz to 1 kHz,
and ±(0.07 % of selected output + 1 mA rms) x f from 1 kHz to 5
kHz, where f = fr equency in kHz.
Resolution ±0.1 mA rms
Temperature Coefficient ±(0.003 % of selected output + 100 µA rms) per °C, above 30 °C
and below 20 °C.
Short Term Stability Output changes less than ±(0.02 % + 500 µA rms) in 10 minutes,
with constant line, load, and temperature.
Harmonic Distortion and Noise ±(0.07 % of output + 1 mA rms) over frequency range of 30 Hz to
1 kHz a noise bandwidth of 300 kHz, ±(0.07 % of output + 1 mA)
x f from 1 kHz to 5 kHz, where f = frequency in Hz.
Line Regulation Output changes less than 0.005 % for ±10 % changes in line
voltage.
Load Regulation For frequencies less than 1 kHz:
±(0.005 % lout + 150 µA) per volt of output compliance voltage.
For frequencies greater than 1 kHz:
±(0.005 % lout + 150 µA) x f per volt of output compliance
voltage, where f = frequency in kHz.
1-3
5 2 20A
Instruction Manual
General
Table 1-2. Specifications (cont.)
Load Capability Drives all resistive and capacitive loads consistent with current and
compliance voltage capability. For inductive loads greater than
1 µH and less than maximum inductive loads, output current is
limited to 16 A rms (22.6 A peak)
Maximum Isolation Voltage ±20 V dc or 20 V ac rms
Temperature Range Operating: 0 °C to 50 ° C
Storage: +20 °C to 56 °C
Relative Humidity 50 % to 50 °C, 75 % to 40 °C, 95 % to 25 °C
Altitude Operating: 0 ft to10,000 ft
Non-operating: 0 ft to 40,000 ft
Vibration 2 g maximum, 5 Hz to 55 Hz for 15 minutes
Shock 15 g maximum, half sinewave
Power Requirements 100, 110, 115, 120, 200, 220, 230, or 240 V ac ±10 %, switch-
selectable, 50 Hz to 60 Hz, 300 W
Weight 27 kg (50 lb)
Dimensions 17.8 cm H x 43.2 cm W x 55.9 cm D (7 in H x 17 in W x 22 in D),
case only (See Figure 1-1).
Protection Safety Class 1 Relates solely to insulation or grounding properties as defined in
IEC 348.
1-4
Introduction and Specifications
Specifications
1
Figure1-1. Outline Drawings
ajs01f.wmf
1-5
5 2 20A
Instruction Manual
1-6
2-1. Introduction
This section of the manual contains information concerning the installation and operation
of the Model 5220A transconductance Amplifier. It is recommended that the contents of
this section be read and understood before any attempt is made to operate the unit. Should
any difficulties arise during operation, contact your nearest John Fluke Sales
representative, or the John Fluke Mfg. Co., Inc., P.O. Box C9090, Everett, WA 98206;
telephone (206) 347-6100.
2-2. Shipping Information
The 5220A is packaged and shipped in a foam-packed container. Upon receipt of the
instrument, a thorough inspection should be made to reveal any possible shipping
damage. Special instructions for inspection and claims are included on the shipping
carton.
If reshipment of the instrument is necessary, the original container should be used. If the
original container is not available, a new container can be obtained from the John Fluke
Mfg. Co., Inc. Please reference the instrument’s model number when requesting a new
shipping container.
Section 2
Operating Instructions
2-3. Input Power
The 5220A can be operated from any one of the following 50 to 60 Hz (±1 %) line
voltages: 100, 110, 115, 120, 200, 220, 230, or 240 V ac (±10 %). A rear panel decal
specifies the voltage selected prior to shipment. If a change in voltage is required, refer to
Section 4 of this manual for the selection procedure.
2-1
5 2 20A
Instruction Manual
2-4. Fuse Replacement
2-5. AC Line Fuse
2-6. Power Supply Fuses
2-7. Rack Installation
The ac line fuse is accessible by way of a rear-panel fuse holder located to the left of the
input power connector. If fuse replacement is required, disconnect the 5220A from line
power and remove the fuse cap and fuse (twist the fuse cap ccw using a screw driver).
Select and install a replacement fuse whose rating is compatible with the local line
voltage.
1. 100 to 120 V ac use fuse type MDA 3 A
2. 200 to 240 V ac use fuse type MDX 1.5 A
Each of the secondary windings on the power transformer is fused to protect the power
supplies from damage in the event of an overload. These fuses, six in al l, are inte rna l to
the 5220A and are not available to the operator. Details for replacement by qualified
personnel are given in Section 4 of this manual.
The 5220A is designed for either bench-top use or for installation in a standard 19-inch
equipment rack using the accessory Rack Mounting Kit (John Fluke P/N M08-205-600).
Chassis slides (John Fluke P/N M00-280-610) can also be installed to facilitate access to
the instrument when it is installed in an equipment rack. Information regarding the
installation of the rack-mounting accessories is included in Section 6.
2-8. Operating Features
The function and location of all 5220A controls, indicators, and connectors are shown in
Figure 2-1 and described in Table 2-1.
2-2
Operating Instructions
Operating Features
2
Figure 2-1. Controls, Indicators, and Connectors
ajs02f.wmf
2-3
5 2 20A
Instruction Manual
Ref.
No Name Function
1 STATUS Indicators Three LEDs that light on an individual basis to indicate that the 5220A
Table 2-1. Controls, Indicators, and Connectors
has exceeded an operating limit. When the limit condition is detected the
5220A is switched to the standby mode. When the limit condition is
cleared the LED will remain lit until the 5220A is commanded to the
operate mode. The three status conditions are as follows:
THERMAL CUTOFF: Indicates that the output stage of the 5220A has
exceeded its maximum operating temperature.
OVERCOMPLIANCE: Indicates that the compliance voltage at the output
terminals has exceeded its limit.
OVERCURRENT: Indicates that the output current has been
programmed beyond its upper limit.
2 CONTROL Switches
and Indicators
3 POWER Switch A push-push switch used to switch instrument power on and off.
4 CURRENT OUTPUT
Terminals (Front)
A series of pushbutton switches and LEDs used to select and indicate
the 5220A operating mode. The function of each is as follows:
OPR/STDBY Switch: Allows alternate selection of the standby and
operate modes.
INPUT Switch: Allows alternate selection of the front and rear input
connectors.
REMOTE Switch: Allows recall of the local mode when remote is
enabled and the LOCAL LOCKOUT LED is not lit.
OPR/STBY LEDs: One of the two is lit to indicate the current operating
mode, operate or standby.
FRONT/REAR LEDs: One is lit to indicate the selected voltage input
connector, front or rear.
REMOTE LED: Lights to indicate that the remote mode has been
remotely selected. If the LED is not lit the local mode is enabled.
LOCAL LOCKOUT LED: Lights to indicate that the unit has been
remotely locked in the remote mode. In this event, the three front panel
CONTROL switches are disabled.
A pair of banana-jack terminals used to provide front-panel connection to
the output of he current source. The terminals are inactive when the rearpanel output terminals are selected.
2-4
5 VOLTAGE INGUT
Terminals (Front)
6 MIS* Bus Connector A 24-pin connector used as an I/O port for remote operation (Fluke MIS
7 Ventilation Filter Prevents dirt and debris from being drawn into the 5220A intake
A pair of banana-jack terminals that serve as control voltage input
connections in the local/front-input mode.
Bus) of the 5220A. When the 5220A is interfaced with a 5100 Series
Calibrator (by way of a Y5000 interface) the 5220A output can be
controlled from the 5100 front panel.
ventilation port.
Operating Instructions
Operating Notes
Table 2-1. Controls, Indicators, and Connectors (cont.)
Ref.
No Name Function
8 Power Connector Provides the means of connecting the 5220A to ac line power by way of
a 3-wire power cord.
9 Fuse Holder Houses the ac line fuse and allows easy access for fuse replacement.
10 Ground Connector A binding post positioned to provide a convenient connection to chassis
ground.
2
11 Current Output
Terminals (Rear)
A pair of banana-jack terminals used as rear-panel current output
connections. The terminals are inactive when the front-panel CURRENT
OUTPUT terminals are selected.
2-9. Operating Notes
The following paragraphs describe the various conditions that should be considered
before operating the 5220A.
2-10. AC Line Connection
The rear-panel three-prong, U-ground connector permits the 5220A to be connected,
through a power cord to 50 or 60 Hz line power. The offset prong on this connector is
connected to the 5220A chassis and should be connected, via the power cord, to a highquality earth ground.
2-11. Transconductance Amplifier
A transconductance amplifier is a current source whose output current level is
proportional to an analog input voltage. Electrically, the output of the unit appears as a
constant current source with an output impedance that is much greater than the load
resistance. Similarly, its input impedance is much greater than that of the input voltage
source.
The input/output ratio of the 5220A is 1:1, and the output current range is +20 to –20 A.
Therefore, the range of the input control voltage is +20 to –20 V dc. The compliance
voltage of the 5220A is 3 V rms ac or +4 V dc.
2-12. Input Voltage Requirements
Input control voltage for the 5220A can be supplied by any low-impedance voltage
source with an output proportional to the desired output current. The source may be either
ac (30 Hz to 1 kHz) or dc, fixed or adjustable, depending upon the output requirements.
The control voltage source may be connected to either the front-panel VOLTAGE
INPUT terminals or the rear-panel voltage input terminals (Pins 5 (low) and 6 (high) of
the 24-pin connector), but not both simultaneously. Instrument damage will not result
from the simultaneous connection of two sources. However, interaction between the two
inputs can result in source loading, which in turn can cause inaccuracy in the expected
current output level.
If a rear-panel input is desirable, the use of the 5100 Series Calibrator and a Y5000
Interface is recommended. This combination allows the 5220A to be operated remotely
as an extension of the 5100. If the use of an alternate rear-input source is desirable, the
user is responsible for the proper interface. Details for custom interface requirements can
be derived from the theory of operation (Section 3) and the detailed schematics (Section
8).
2-5
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Instruction Manual
2-13. Input Voltage Selection, Front/Rear
2-14. Current Output, Front/Rear
2-15. Standby/Operate
Selection of the front or rear terminals for control voltage input is manually accomplished
by pressing the INPUT push button switch on the front panel. Each depression alternately
selects front or rear as indicated by the lit FRONT/REAR LED indicator. This switch is
active in the local mode, and inactive in the remote mode.
The 5220A current output can be taken from either a front- or rear-panel set of five-way
binding post terminals, but not both simultaneously. An internal jumper configuration
allows qualified personnel to establish the desired output. A detailed output selection
procedure is given in Section 4, Maintenance.
When the 5220A is energized it can be placed into one-of-two operating modes; standby
or operate. The enabled mode is indicated by a lit front panel LED; OPR (operate) or
STDBY (standby). Standby is essentially a reset state, in which the output of the
transconductance amplifier is forced to zero regardless of the input control voltage level.
In the standby mode both the amplifier and the device connected to its output are
protected from accidental overloads. The operate mode is enabled when an output is
required. It causes the amplifier to respond to the control voltage input, and thereby
provides the appropriate current level output.
A front panel pushbutton switch (located between the OPR/STDBY LEDs) allows
manual selection of either mode when the LOCAL LOCKOUT LED is not lit. However,
the selection can be counteracted under certain conditions. For example, either mode may
be remotely selected, and the detection of an output overload will command the standby
mode. Similarly, when the unit is initially energized it is forced to standby.
2-16. Local/Remote
The 5220A can be operated manually using the front panel controls, or remotely by way
of the rear panel connector. When the unit is initially energized, it is forced to the local
control mode (REMOTE LED is not lit). The remote mode can only be selected by way
of a remote control source. When remote is enabled (REMOTE LED is lit) the local
mode can be recalled by a remote command or by pressing the LOCAL push-button
switch on the front panel. However, if the LOCAL LOCKOUT is lit (this is also a remote
command) the local mode can only be recalled by a remote command.
2-17. Status Indicators
A series of three front-panel STATUS LEDs provide a visual indication of overload
conditions that have been detected at the 5220A output. They are: THERMAL CUTOFF,
OVERCOMPLIANCE, and OVERCURRENT. When any one of these conditions is
detected the appropriate LED is lit and the unit is commanded to standby. The LED will
remain lit even after the overload condition has been relieved. To return the unit to the
operate mode the overload must be cleared and the operate mode must be commanded. If
operate is commanded while the overload is still present, the unit will remain in standby.
2-6
A thermal cutoff indication identifies overheating of the current output stage. If the
heating is excessive a cooling-down period may be required before the condition is
cleared.
The presence of an open-circuit or a high impedance load at the output terminals will
cause an overcompliance indication. In this case, an appropriate load will have to be
connected to the output before the condition can be cleared. Overcompliance is detected
as an output voltage outside the range of +4 V dc or 3 V rms ac.
Output current in excess of 20 A will cause an overcurrent indication. To correct the
condition, the input control voltage must be reduced to an acceptable level.
2-18. Audible Output
When the 5220A is used to output high current at high frequencies (above 10 A and 1
kHz) it may emit an audible tone. The sound is normal and is characteristic of power
transistors that are operated at high current density. Several factors will cause the sound
to be more or less apparent. They include background noise, location of the 5220A
relative to the operator, and operator’s hearing ability.
2-19. Inductive Loads
The 5220A will drive an inductive load of up to 200 µH. However, reasonable care must
be exercised to ensure the desired results. One or more of the following considerations
may apply to a given application:
1. Compliance voltage (3.0 V maximum) places a restriction on the product of
inductance and operating frequency for a given output current. This is illustrated in
Figure 2-2 for maximum load inductance vs frequency at output currents of 5, 10,
and 20 A.
Operating Instructions
Operating Notes
2
2. A step change in output current into an inductive load can easily produce an
overcompliance condition. If the control voltage is being input at the front panel
terminals, the rate of change must be controlled to avoid an overcompliance trip. An
alternate approach is to set the 5220A to standby before making a change in the
control voltage, then select the operate mode. This allows the 5220A to internally
control the rate of change. If the control voltage is taken fr om a Fluke Mode l 5100
Series Calibrator, the calibrator will limit its output to an acceptable rate of change.
3. The leads used to connect a load to the 5220A can add appreciably to load
inductance. For example, a pair of 5-foot leads (10 feet of wire) made of 18 gauge
wire (AWG) will have a calculated inductance of 3.86 µH. This is enough to cause an
overcompliance trip if a step change in the input control voltage occurs.
4. When driving an ac current through an inductive load the 5220A will exhibit
increased distortion and transconductance error. This is due to a reduction in loop
gain caused by the inductance. The graph in Figure 2-3 illustrates the typical
transconductance error, as a function of frequency, for two different inductive load
values.
2-7
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Instruction Manual
Figure 2-2. Maximum Load Inductance vs Frequency
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2-8
Operating Instructions
Operation
2
Figure 2-3. Typical Transconductance Error for Inductive Loads
2-20. Operation
The following procedure is suggested for operating the 5220A. With reference to the
previous paragraphs proceed as follows:
1. Connect the 5220A to the 5100 Series Calibrator via the Y5000 Interface if remote
operation is desired. See the 5100B/Y5000 Instruction Manuals for details.
2. Connect the 5220A to line power.
3. Turn-on the 5220A by depressing the POWER switch to the ON position. Only the
STDBY and FRONT indicators should be lit.
4. Energize peripheral equipment as required.
5. If local operation is required, connect the control voltage source to the front-panel
VOLTAGE INPUT terminals.
6. Adjust the output of the control voltage source (remote or local) to approximately
1 V.
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5220A
Instruction Manual
7. Determine the active output terminals (front or rear) by connecting a short jumper
wire between the front-panel CURRENT OUTPUT terminals and then pressing the
OPR/STDBY switch. If the OVERCOMPLIANCE LED lights, the rear output
terminals are active. Otherwise, the OPR LED will light indicating that the front
CURRENT OUTPUT terminals are active.
8. Press the STDBY switch and then remove the short from the front output terminals.
9. Connect the intended load between the active output terminals.
10. Adjust the control voltage to the desired level.
11. Command the operate mode. If the OPR LED is lit, the predetermined current level is
flowing through the load.
12. Set the unit to standby before disconnecting the load or setting the POWER switch to
OFF.
2-10
Theory of Operation
3-1. Introduction
This section of the manual contains an overall functional description followed by a
detailed circuit analysis of the 5220A. Both descriptions are supported by block
diagrams. Component level descriptions contained in the circuit analysis are referenced to
the detailed schematics in Section 8 of this manual.
3-2. Overall Functiona l Description
3-3. General
The 5220A is a transconductance amplifier. That is, a current source whose output
current is proportional to an analog input voltage. Electrically viewed at the output
terminals, the 5220A appears as a current source with an output impedance that is very
much greater than the load resistance. It s inp ut te rm ina ls exhib it a similar cha rac teri s ti c;
the input impedance is larger than that of the input voltage source.
Section 3
Functionally, the 5220A, as shown in Figure 3-1, can be divided into two sections, analog
and digital. The analog section consists of the power supplies, the transconductance
amplifier, and associated analog control circuitry. The digital section comprises the logic
necessary for overall control, and the interfaces necessary for front panel (local)
operation and remote operation by way of the Fluke MIS Bus.
3-4. Analog Section
The power supply used in the 5220A provides operating voltages for both the analog and
the digital section of the unit. It consists of three separate assemblies: the A2 Transformer
Assembly, the A3 Cap Bus, and the A4 Regulator. The Cap Bus and Regulator
Assemblies comprise the output po rtion of the supply, while the Transformer Assem bly
provides isolated ac power for the power supplies. Regulated supply voltages are a
function of the A4 Regulator. These include +5 V dc and +5 V dc Isolated for the digital
circuits and +15/-15 V dc for analog circuit operation. Unregulated voltages are a
function of the A3 Cap Bus. The Cap Bus is a high-current, +12/-12 V dc source for the
5220A current output.
3-1
5 2 20A
Instruction Manual
3-2
Figure 3-1. 5220A Functional Block Diagram
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