Fluke 540B User manual

P/N 294033
March 1968
540B
Thermal
Transfer
Standard
Instruction Manual
FLUKE

WARRANTY
Notwithstanding any provision of any agreement the follo win g warran ty is exclusive:
The JOHN FLUKE MFG. CO .. INC
.. warrants each instrument it manufactures to be free from defects in material and
workmanship under normal use and service for the period
of 1 year from date of purchase. This warranty extends only
to the or iginal purchaser. This warranty shall not app ly to fuses. disposable batteries (rechargeable type batteries are
warranted
for 90 days), or any product or parts which have been subject to misuse, neglect, accident, or abnormal
conditions
of operations.
In the eve
nt of failu re of a product covered by this warranty, John Fluke Mfg. Co., Inc., will repair and calibrate an
instrument returned to an authorized Service Facili ty within 1 year of the original purchase; provided the warrantor's
examination discloses
to its satisfaction that the product was defective. The warrantor may, at its option, replace the
product in lieu
of repair. With regard to any instrument returned within 1 year of the original purchase, said repairs or
replacement will be made without charge. If the failure has been caused by misuse, neglect, accident, or abnormal
conditions
of operations, repairs will be billed at a nom inal cost. In such case, an estimate will be submitted before
work is started,
if requested.
THE FOREGOING WARRANTY IS IN LIEU OF ALL OTHER WARRANTI
ES, EXPRE SS OR IMPLIED,
INCLUDING
BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS,
OR ADEQUACY FOR ANY PARTICULAR PURPOSE OR USE. JOHN FLUKE MFG. CO., INC., SHALL
NOT BE LIABLE FOR ANY SPECIAL, INCIDE NTAL , OR CONSEQUENTIAL DAMAG ES , WHETHER IN
CONTRACT, TORT, OR OTHERWISE.
If any failure occurs, the following steps should be taken:
1. Notify the
JOH N FLUKE MF G. CO., INC., or nearest Service faci li ty , giving full details of the difficu lt y, and
include the model numbe
r, type number, and serial numb er. On recei pt of this information, service data, or
shipping instructions will be forwarded to you.
2. On receipt of the shipping instructions, forward the instrument, transportation prepaid. Repairs will be
made at the Service
Fa cility and the instrument returned, transportation prepaid.
SHIPPING TO MANUFACTURER FOR REPAIR
OR ADJUSTMENT
All shipments
of JOHN FLUKE MFG. CO. , INC ., instruments should be made via United Parcel Service or "Best Way"*
prepaid. The instrument should be shipped in the
or igin al packing carton; or if it is not available, use any suitable
container that is rigid and
of adequate size. If a substitute container is used, the instrument should be wrapped in paper
and surrounded w
ith at least four inches of excels ior or similar shock-absorbing material.
CLAIM FOR DAMAGE
IN SHIPMENT TO ORIGINAL PURCHASER
The instrument should be
thor oughly inspected immediately upon original delivery to pur chase r. All material in th e
container should be checked against the enclosed packing list. The manufacturer will
not be responsible for shortages
against the packing sheet unl
ess notif ied immediately. If the instrument is damaged in any way, a claim should be fil ed
with the carrier immediately. (
To obtain a quotation to repair sh ipment damage, contact the nearest Fluke Technical
Center.} Final claim and negotiations with the carrier must be completed
by the customer.
The JOHN FLUKE MFG. CO., INC,
will be happy to answer all applications or use questions, which will enhance your
use of th is instrument. Please address your requests or correspondence to: JOHN FLUKE MFG. CO., INC., P.O. BOX
C9090, EVERETT, WASHINGTON 98206, ATTN: Sales Dept. For European Customers: Fluke (Holland) B.V.,
P.O. Box
5053, 5004
EB , Tllbu rg, The Netherland s.
'For Eu ropean customers, Air Freight prepaid.
John Fluke Mfg . Co., Inc ., P.O. Box C9090, Everett, Washington 98206
Rev. 6/ 81

Section
I
II
m
TABLE OF CONTENTS
Title
INTRODUCTION AND SPECIFICATIONS
1-1. Introduction . . .
1-7. Specifications . .
1-8. Electrical
1-9. Mechanical
1-10. Accessories ...
1-11. High Frequency Therma l Converters.
1-13. Current Shunts . . . . . . . . . .
OPERATING INSTRUCTIONS
2-1. Controls, Terminals, and Indicators
2-3. Auxilliary Equipment Needed
2-6. Methods of Operation .
2-8. Preliminary Operation ...
2-9. Precautions . . . . .
2-11. Battery Check . . . .
2-13. Deflection Sensitivity.
2-15. DC Reversal Error .
2-17. Voltage Measurement and Calibration
2-18. Measuring an Unknown AC Voltage
2-20. Calibrating an AC Voltage Source .
2-22. Current Measurement and Calibration . .
2-23. General. . . . . . . . . . . . .
2-28. Measuring an Unknown AC Current
2-30. Calibrating an AC Current Source .
2-32. High Frequency Voltage Measurement and Calibration
2-33. General . . . . . . . . . . . . . . . . . .
2-35. Measuring an Unknown High Frequency Voltage
2-37.
Calibrating a High Freq uency Voltage Source
THEORY OF OPERATION
3-1. Introduction . .
3-3. General . . . .
3-9. Circuit Descriptions
3-10. Search Circuit.
3-13. Protection Circuit
3-19. Thermocouple . .
3-21. Reference . . . :
3-23. Galvanometer ..
3-29. Battery Check Circuits . .
3-33. Rechargeable Battery Pack
Page
1-1
1-1
1-1
1-1
1-2
1-2
1-2
1-2
2-1
2-1
2-1
2-3
2-3
2-3
2-5
2-5
2-5
2-8
2-8
2-8
2-8
2-8
2-8
2-8
2-10
2-10
2-10
2-10
3-1
3-1
3-1
3-2
3-2
3-2
3-3
3-3
3-3
3-4
3-5
(continued ii)
540B

540B
Table of Contents (continued)
Section
IV
v
VI
VII
VIII
Ti tle
MAINTENANCE
4-1.
4-4.
4-6.
4-9.
4 -19.
4-34.
4-36.
General ..... . . ... .
Battery Installation and Removal
Battery Check Calib ration . . .
Periodic Maintenance . . . . .
4
-10. Search Meter Calibration
4-12. Protection Ampl ifier Calibration.
4-14. Galvanometer Calibration
4- 18. Sensitivity Te st Calibration ...
Preliminary Transfer Calibration Check
4-20. General . . . . . . . . . . .
4-24. Reversal E rr or . . . . . .
4 -28. Ga lv anometer Ground Isola tion
4-30. Galvanomet er Input Isolation
4-32. Protection Disable Check (Model A54-2)
Transfer Calibration Check
Troubleshooting . . . . . . . .
4-37. General . . . . . . . . .
4-39. Thermocouple Replacement
LIST OF REPLACEABLE PARTS
5-1. Introduction . . . .
5
-4. How to Obtain Parts .
5-7. List of Abbreviations
5 -8. Serial N umber Use Codes
ACCESSORIES
6-1. Model A55 Thermal Converters
6-2. Introduction .
6-4. Construction .
6-6. Specifications.
6-7. Accessories .
6-9. Model A40 and A40A Current Shunts.
6-10. Introduction .
6-12. Construction .
6-14. Specifications
6-15. Accessorie s
GENERAL INFORMATION
7-1. List
of Abbreviations . . . . .
7-2. Federal Supply Codes
for Manufacturers
7-3. Fluke Technical Service Centers . .
7-4 . Sales Represe
nta t ives- Domestic. .
7
-5 . Sales Representatives -International
SCHEMATIC DIAGRA
MS
Model 540B Transfer Standard
Model A54-2 Voltage Plug-In Unit
ii
Page
4-1
4-2
4-2
4-2
4-3
4-3
4-3
4-3
4 -5
4-5
4-5
4-5
4 -5
4-6
4-6
4-6
4-7
4-7
4-7
5-1
5-1
5-2
5-2
5 -24
6-1
6-1
6-1
6-1
6 -2
6-2
6-2
6 -2
6-2
6-3
6-3
7-1
7-1
7-3
7-10
7-11
7-13
8-1
8-1
8-2

------ --- --------------- - - -
Figure
Frontispiece
2-1.
2-2.
2-2.
2- 3.
2- 4.
2-5.
2-6.
2- 7.
2-8.
2-9.
2-10.
2-11.
2-12.
3-1
3- 2.
3- 3.
3-4.
LIST OF ILLUSTRATIONS
Title
540B Thermal Transfer Standard
Location of Controls, Terminals, and Indicators
Front-Panel Controls, Terminals, and Indicators (Sheet 1 of 2)
Front-Panel Controls, Terminals, and Indicators (Sheet 2 of 2)
Recommended Auxiliary Equipment
Battery Check . . .
Deflection Sensitivity
Measuring an Unknown AC Voltage
Calibrating an AC Voltage Source
Cables and Connections for Current Shunts
Measuring an Unknown AC Current .
Calibrating an AC Current Source
Measuring an Unknown HF Voltage
Calibrating a HF Voltage Source
540B Block Diagram . . .
Simplified Balance Network
Galvanometer Block Diagram
540B Rechargeable Battery Pack
iii
Page
v
2-1
2-2
2- 3
2-4
2- 5
2- 6
2-7
2- 9
2-10
2-11
2-12
2-13
2-14
3-1
3-3
3-4
3-5
(continued iv)
540B

540B
Li
st of lllustra t ions (continued)
Figure Tit l e
Pag e
4- 1. Calibration and Test Equipment
4 -1
4- 2. Battery Check Calibration Adjustments
4-2
4- 3. Electronic Galvanometer Cali b ration . 4- 4
4-
4. Tune d Carrier Amplifier Adj ustmen ts
4-4
4- 5. Transfer Calibration Check
4- 6
4- 6.
Troubleshooting
4- 7
5-
l. Final Assembly (Sheet 1 of 2) 5- 3
5-
l.
Final Assembly
(Sheet 2 of 2)
5-4
5-2 . Front Pane l Assembly
5- 5
5-3. Oscillator / Synchronous Demodulator
5-8
5- 4. Magnetic Modulat or / Carrier Amplifier
5-11
5-5.
Search and Pro t ection Amplifier Assembly
5-13
5- 6. A54-1 and A54- 2 Final Assembly
5- 15
5-7.
Panel Assembly
5- 16
5-8. Range Switch Assembly
5- 19
5-9. Range Board Assembly
5- 20
5-10. Compensation Board Assembly
5 -2 1
5-11.
540B-110 Rechargeable Battery Kit
5 -22
-- .
6-1.
Model A 55 Thermal Conve. rters and Accessories .
6-1
6- 2.
Current Shunts . 6
-2
6-3.
Current Shunt Accessories
6- 3
iv
.. ..

540B
MODEL 5408 T HERMAL TRANSFER STANDARD
v

540B
SECTION I
INTRODUCTION AND SPECIFICATIONS
1-1.
INTRODUCTION
1-2. The Model 540B, together with the Model A54-1
or Model A54-2 Voltage Plug-In Units, constitutes an
AC-DC
Thermal Transfer Standard. The unit has 14
ranges of input from 0. 5 volts to 1, 000 volts. It is
furnished complete with a solid-state galvanometer,
internal reference, search meter and battery power
supply. A voltage protection circuit protects all in-
ternal circuits from damage as a result of over-voltages
of up
to 1, 500 volts on any range. Since the instrument
does not require critical positioning or environment, it
is suitable for application as a Laboratory Standard,
yet hardy enough for use as a production line or field
instrument.
1-3. The solid-state galvanometer does not require
special mechanical orientation for proper operation and
is no more fragile than any normal meter movement.
The circuit is equipped with an internal calibration cir-
cuit that provides easy and rapid calibration of meter
deflection sensitivity representing 0. 1% and . 01% at any
input.
1-4. The internal reference is adjusted by Coarse,
Medium and Fine controls that provide continuous ad-
justment over the entire range of input levels. Good
resolution is possible at levels below 50% of rated in-
put, but sensitivity is sacrificed with the lower levels
of input.
1-5 . A search meter function has been included which
makes the selection of the operating range certain and
rapid.
1-6. The self-contained battery pack will operate the
instrument independent of power sources.
1-7. SPECIFICATIONS
1-8. ELECTRICAL
VOLTAGE RANGES
0. 5, 1, 2, 3, 5, 10, 20, 30, 50, 100, 200, 300, 500 and
1000 volts.
Transfers may be made on each range from
1/2 to 1 times range voltage. Transfers may be made
at levels considerably below the 1/2 of range level, but
at the sacrifice of sensitivity.
ACCURACY
Range
Frequency
AC/DC
Difference
All except 1000v 5 Hz
to
50kHz ±.01%
1000v 5
Hz to
20kHz ±.02%
1000v 20kHz
to
50kHz ±.04%
0. 5
thru 50v 50kHz
to 100kHz ±.05%
20 thru 50v 100kHz
to 500kHz ±0.1%
0. 5 thru 10v 100kHz
to 1M Hz ±0.1%
100
thru 500v 50kHz
to 100kHz ±0.
2%
CALIBRATION
Each
range is adjusted to be within the above deviations
from zero as defined by reference standards maintained
by the John Fluke Standards Laboratory, which
are peri-
odically calibrated by the National Bureau of Standards.
These AC/DC difference specifications do not include
the National Bureau of Standards random and syste-
matic error uncertainties. John Fluke Standards Lab-
oratory or National Bureau of Standards calibration
reports are available at extra cost.
INPUT IMPEDANCE
182 ohms/volt
in all voltage modes.
THERMOCOUPLE REVERSAL ERROR
Less than 0. 01% of input at 100% of rated current or
voltage. Less than 0. 03% at 50% of rated current or
voltage.
GALVANOMETER
Solid-state electronic type with a resolution of 0. 0012%
of input/scale division at rated input. 0. 006% of input/
scale division at 1/2 of rated input.
SEARCH CIRCUIT
Solid-
state circuit provides visual . indication of input
voltage
as a percentage of the voltage range selected.
OVERLOAD PROTECTION
The entire instrument is protected from accidental over-
loads of up to 1, 500 vdc or rms ac in any range .
1-1

540B
PROTECTION DISA
BLE
A push button switch that removes the diode circuit from
the input to the thermocouple . Incorporated only in the
A54-2 plug-in Wlit.
1- 9. MECHANICAL
SJZE
7" high x 17" wi de x 7-3 / 4" deep (1 9" wide with 88 1A-
103 rack moWlti ng kit installed) .
WEIGHT
18 poWlds, 9 Ounces w it h batteries .
1-10. ACCESSORIES
1-11. HIGH FREQUENCY THERMAL CONVERTERS
1-2
1- 12. Nine Fluke Model A55 High Frequency Thermal
Conver ters are available for use with the Model 540B
extending the frequency response to 50 MHz. One is
pro vided for each voltage range of the 540B from 0. 5
volts to 50 volts, and may be used from 1/2 to 1 times
their rated voltage . It is possible to use the Thermal
Conver ters at levels below 1/2 their rated input by
sacrificin g sensitivity.
1 -1 3. CURRENT SHUNTS
1-14. Fourteen Fluke Model A40 Current Shunts are
available for use with the Model 540B, for curre nt
transfer measurements of 2. 5 ma to 20 amp s, over a
frequ ency range of 5Hz to 100kHz with a b asic transfer
accuracy of ±0 .02%. Current transfer measurements
may be made well below 2. 5 ma, but sensitivity will be
reduced.

static awareness
A Message From
John Fluke Mfg. Co., Inc.
Some semiconductors and custom IC 's can be
damaged
by electrostatic discharge during
handling. This notice explains how you can
minimize the chances
of destroying such devices
by :
1. Knowing that there is a problem.
2. Learning the guidelines for handling them.
3. Using the procedures, and packaging and
bench techniques that are recommended.
The Static Sensitive (S.S.) devices are identified
in the Fluke technical manual parts list with the symbol
..
The following practices should be followed to minimize damage to S.S. devices.
1. MINIMIZE HANDLING
2. KEEP PARTS IN ORIGINAL CONTAINERS
UNTIL READY FOR USE.
3. DISCHARGE PERSONAL STATIC BEFORE
HANDLING
DEVICES. USE A HIGH RESIS-
TANCE GROUNDING WRIST STRAP.
4 HANDLE S.S. DEVICES BY THE BODY
Page 1 of 2

5. USE STATIC SHIELDING CONTAINERS FOR
HANDLING AND TRANSPORT
6.
DO NOT SLIDE S.S. DEVICES OVER
ANY SURFACE
7. AVOID PLASTIC, VINYL AND STYROFOAM®
IN
WORK AREA
PORTIONS REPRINTED
WITH PERMISS
ION FROM TEKTRONIX, INC.
AND GENERAL DYNAMICS. POMONA OIV.
╕ Dow Chemical
Page 2 of 2
8. WHEN REMOVING PLUG-IN ASSEMBLIES,
HANDLE ONLY BY NON-CONDUCTIVE
EpGES AND NEVER TOUCH OPEN EDGE
CONNECTOR EXCEPT
AT STATIC-FREE
WORK STATION. PLACING SHORTING
STRIPS ON EDGE CONNECTOR HELPS
TO
PROTECT INSTALLED SS DEVICES.
9. HANDLE S.S. DEVICES ONLY AT A
STAT IC -FREE WORK STAT ION
10. ONLY ANTI-STATIC TYPE SOLDER-
SUCKERS SHOULD BE USED.
11.
ONLY GROUNDED T IP SOLDERING
IRONS SHOULD BE USED.
A complete line of static shielding bags and acces-
sories is available from Fluke Parts Department,
Telephone [phone] or write to:
JOHN FLUKE MFG. CO., INC.
PARTS DEPT. MIS
86
9028 EVERGREEN WAY
EVERETT, WA 98204
J0089D-07U8604/SE EN Litho in U.S.A.
Rev.1 MAR 86

540B
SECTION II
OPERATING INSTRUCTIONS
2 - 1. CONTROLS, TE RMINA LS A ND INDICA TORS
2- 2. The location, circuit symbol, and a functional
description of the external controls, terminals and
indicators on the Model 540B may be found in Figures
2-1 and 2-2.
Note!
Warranty and shipping information found
on Warran ty page at rear of manual.
2 - 3. AUXILIARY EQ U IPMEN T N EEDED
2-4. The Model 540B Thermal Transfer standard with
the equipment listed in Figure 2- 3 will form a complete
2 5 4 3
8 7
6 9
system capable of measuring an ac voltage or current ,
calibrating ac voltage or current measuring devices and
measuring frequency response. Since all transfer
measurements are made by comparison, accuracy is
dependent upon the accuracy of the transfer standard
and the accuracy of the de measuring equipment. It is
also necessary that the ac being measured must be at
least as stable as the degree of accuracy desired. The
National Bureau of Standards will check a Model 540B
and issue a test report at specified frequencies and
voltages upon requ est . However, as requested by the
National Bureau of Standards, we suggest that these
tests can be done in the Fluke traceable standards labo-
ratory. This helps reduce the National Bureau of stand-
ards work load and also reduces customer waiting time.
17
12
ll
10
13
13
14
16 15
Figure 2- 1. LOC AT I ON OF CONTROLS, TERMINALS AND IND I CATORS
2-1

540B
REF
NAME REF FUNCTION
NR. DESIG
1
PERCENT INPUT M 10 1
Search circuit indicator which reads % of input/range
sele cted. Indicates battery condition, which is adequat e
when the
me t er reads above the lower lim it of the BAT
band on the
meter scale.
Indicates that the protection
c ircuit h as operated and needs resetting, when the needle
is in the OVER LOAD area.
Does not function in current
sh unt op eration.
2 GALVANOMETER M 102 Th e null indica ting device us ed to determine the balance
between the variable reference voltage and the thermo-
coup le output.
3 POWER s 101 Applies
battery power to the instrument in the ON position.
Wh en in the BATTERY CHECK; REFERENCE, GALV or
SEARCH position s the PERCE NT INPUT meter will indi-
cat e the condition of each set of batteries.
4 SENSITIVITY s 105 U
sed to select the range of galvanometer sensitivity;
LOW, MED and HIGH.
5 GALV ZERO
R4 The elect rical zero adjustment for the galvanometer.
6 HIGH FREQ CONVERTER J 102 Used to at tach an external high frequency converter, such
as th e Fluke Model A55 Thermal Converters, to the in-
stru m ent . May also be used to connect an external galva-
nomete r. When not in use the three-pron g captive plug
P 101, must be plugged in.
7 GALV s 104
Ele c trically connects the galvanometer circuit between
th e th e rmocouple output and the variable internal reference
wh en in the LOCK or MOMENTARY positions. The GALV
sw
itc h is b riefly pushed from OPEN to MOMENTARY to
d ete rmine if the galvanometer will indicate on scale with-
ou t f urther adjustment.
After an on scale indication is
obtain ed, the GAL V switch may be set to LOCK.
8 SENSITIVITY
TEST s 102 Used to determine the amount of deflecti on of the galva -
nometer for 0. 1% and 0. 01% changes in input.
9 REFERENCE ADJUST s 103 The COARSE, MEDIUM and FINE controls vary the refer-
R 405 ence v ol tage for galvanometer balance.
R408
10 MODE s 801 Selects SEARCH or TRANSFER modes for either AC or
DC input to the instrument. Range selection is made in
th e SEA RCH modes by selecting a voltage range that gives
a PERCENT INPUT meter indication between 50% and
100
%. The TRANSFER positions connect the selected range
to the th ermocouple . Transfers may be made at inputs
below
50% but sensitivity will diminish. Should
an over-
load occur, the Model 540B may be reset by switching the
mode switch to OFF and then back to the desired mode.
11 RANGE
s 501 S elects the proper dropping resistor and compensating
netwo rk for measurements of voltages up to and including
th e vo ltage indicated (de or ac rms ). The SHUNT position
is us ed w ith Fluke Model A40 Current Shunts.
12 POLARITY s 802
Is u se d to re v erse the input to the thermocouple to facili-
tat e t he measurement of the turn-over error of the thermo-
coup le .
Figure 2-2. FRONT -PANEL CONTROLS, TERMINALS, AND INDICATORS (Sheet 1 of 2)
2-2

540B
REF
NAME
REF
FUNCTION
NR. DESIG
13 SHUNT J 805 Binding
posts provided to accept the Fluke Model A40
J 806
Current Shunts. A locking screw for the larger shunts
is provided and is locat ed on the rear panel of the Model
A54
plug-in unit. Without a Model A40
plug-in the i nstru-
ment has a basic current range of 2. 5 to 5 ma.
14
DC INPUT J 801
Binding posts, with centers 3/ 4 inch apart, are provided
J 803 for connecting de voltage to the A54. Connect the positive
lead to the upper post. The lower post is chassis ground.
15 AC INPUT J 802 A dual
purpose AC INPUT connector arrangem ent is pro-
J 804 vided in the .Model A54. AC voltages may be applied to the
unit through the UHF type connector or, since a separate
ground post is located 3/4 inch from the UHF connector's
center, a standard dual banana plug.
16 PROTECTION DISABLE s
803 Disconnects the diode protection circuit in parallel with the
(Model A54-2 only)
thermocouple, when depressed . Depression of the switch,
while at null (zero) on the GALVANOMETER meter in the
AC TRANSFER mode, will cause a deflection.
If the de-
flection at each frequency and on each range of interest is
noted periodically, the change in deflection will then be an
indication of the long term stability performance of the
transfer portion of the unit including the protective cir-
cuitry.
17 PANEL
BUSHING
NONE
An internally threaded bushing used in conjunction with
the current shunt retaining screw.
Figure 2 -2 . FRONT-PANEL CONTROLS, TERMINALS, AND INDICATORS (Sheet 2 of 2)
2-5. Should lesser degrees of accuracy suffice for any
application, the specifications for auxiliary equipment
as shown in Figure 2-3 may be reduced. For additional
application information contact your Fluke
repres enta -
tive or the factory.
2-6 . METHODS OF OPERATION
2-7. There are many different methods of making
accurate transfer measurements. The methods outlined
in this manual are suggested as being adequate. Infor-
mation about
transfer measurements, methods, theory,
etc. may be found in the following references:
a. THERMAL CONVERTERS AS AC-DC TRANSFER
STANDARDS FOR CURRENT AND VOLTAGE MEAS-
UREMENTS AT AUDIO FREQUENCIES, F. L.
Hermach, J. Research 48, 121 (1952} RP2296.
b. A WIDE-RANGE
VOLT - AMPERE CONVERTER
FOR CURRENT
AND VOLTAGE MEASUREMENTS,
AlEE Transactions, Communications and Elec-
tronics, Paper No. 59-161 (1959}. F. L. Hermach
and E. S. Williams.
c. CALIBRATION OF VOLT-AMPERE CONVERTERS,
National
Bureau of Standards Technical Note 188,
(1963} E. S. Williams.
2-8. PRELIMINARY OPERATION
2- 9. PRECAUTIONS
2-10. High
order accuracy can be obtain ed with this
Transfer Standard only if the user is aware of certain
limitations and takes appropriate precautions as follows:
a. Bead type thermocouples, like that used in the Model
540B, exhibit a
small exponentially decreasing drift
of emf after a steady heater current is initially
applied. Allow approximately 10 minutes for the
thermocouple element to stabilize. After the stabi-
lization time, the drift should be less than 2 small
divisions per minute in the HIGH sensitivity position.
When
changing to different levels of input, after
the stabilizati on period, a wait of only a few minutes
is necessary before continuing with measurements.
Any observed drift should be evaluated quanti -
tatively.
b. Connection errors should be evaluated and min i-
mized when the Transfer Standard is used to cali -
brate other instruments. These errors can often
be
detected by changing the length and position of
the
leads. Short coaxial leads should be used when
possible. These errors can be significant at high
test frequ encies .
2-3

540B
FUNCTION SPECIFICATIONS DESIRED APPLICATION RECOMMENDED INSTRUMENT
FOR MAXIMUM ACCURACY
AC Voltage AMPLITUDE STABILITY: Supplying
an ac volt-
No one ac source will meet the
Source . 01% short term.
age for setting up a specifications desired for maxi-
AMPLITUDE RESOLUTION:
calibrated ac voltage mum accuracy over the fre-
. 002% at desired output
and measuring fre- quency range covered. AC signa l
voltage.
quency response of sources and amplifiers that will
OU T PU T VOLTAGE: voltage indicating
give satisfactory results in most
0. 225 to 1000 volts. instruments and volt - applications are made by Boonton
OUTPUT CURRENT:
age amplifiers . Radio Corp. , Hewlett Packar d,
5 to 10 rna. Holt Inst. Lab., Krohn -Hite,
FREQUENCY: Optimation, Rohde
and Schwarz,
Dependent on application. and Tekt ronix Inc.
DC Voltage AMPLITUDE STABILITY: Supplying
the de vo lt- John Fluke Model 332A Voltage
Sourc e . 002% short ter m.
age equal to the rms Calibrator, which has th e ad-
AMPLITUDE RESOLUTION:
value of the ac vol t- ditional fea ture in calibration
. 002% at desired output.
age to be measured. accura cy of . 003% which would
OUTPUT VOLTAGE:
eliminate the requirement for
0. 225 to 1000 volts. DC voltage measuring equip-
OUTPUT CURRENT:
ment in many cases.
5 to 10 rna.
De Voltage RANGE:
Accurate calibration John Fluke Model 885A Differ -
Measuring
0. 225 to 1000 volts . of
the de source. ential Voltmeter offers adequa te
Equipment ACCURACY:
accuracy and stability for u se in
.003 %.
th is system.
AC Current
AMPLITUDE STABILITY: Supplying an ac cur- In most cases it will be neces-
Source
. 01 % short term. rent for setting up a sary to use a variable vol tage
AMPL ITUDE RESOLUTION: calibrated ac current source and an appropriate
. 002% at desired output
and measuring fre- resistor.
current . quency response of
OUTPUT CURRE
NT : current measuring
2. 5 rna to 20 amperes. devices.
OU T PUT VOLTAGE:
Approximately 1v in excess
of the voltage required by the
network under test.
FREQUENCY:
Dependent
on the application.
DC Current AMPLITUDE STABILITY: Supplying the de cur-
In most cases it will be neces-
source . 0 02 % short term.
rent equal to the rms sary to use a variable voltage
AMPLITUDE RESOLUTION:
value of the ac cur- source and an appropriate re-
. 002% at desired output rent to be calibrate d
sistor. For many applica tions ,
curren t.
or measured. the Fluke Model 382A Voltage/
OUTPUT CURRENT:
Current Calibrator will be very
2. 5 rna to 20 amperes.
useful.
OUTPUT VOLTA
GE :
Approximately 1 v in excess
of the voltage requir ed by the
network under test .
DC Current RANGE: A ccurate measurement
U se a standard resistor and the
Measuring 2. 5 rna to 20 amperes. of the de cu . rrent flow. de vol tage measuring equipment
Equipment ACCURACY: previously recommended. If the
.0 1%. Fluke Model 382A Voltage/ Cur-
STABILITY:
rent Calibrator is used curren t
. 01%
short term. measuring equipment will not
be needed within the calibrator
range.
AC Current RANGE: Appr oximate current
Use common commercial
Measuring 2. 5 ma to 20 amperes. measurement to pre -
ammeter.
Equipment ACCURACY: 10 %. vent shunt damage.
Figure 2- 3. 540B AUXILIARY EQUIPMENT LIST
2-4

c. Radio Frequency Interference can be particularily
troublesome with low-current thermoelements.
The thermocouple in the Model 540B is incased in
a
steel shield to minimize stray field pick -up.
However, to insure accuracy, the Model 540B
should be used in areas of relatively low field
strength.
d. The number of transfers will vary with the degree
of
accuracy required. In general it is suggested
that three seperate transfers (de to ac and back to
de constitutes one transfer) be made for any single
measurement. This will be adequate only if a good
degree of repeatability is achieved. Difficulty in
repeating any measurement can be caused by any
number of problems, the most common of which
are poor collllections, unstable sources, and inter-
ference from stray capacitance or energy fields.
Any factor which detracts from repeatability must
be eliminated before accurate transfers can be
made.
e. All of the components and elements in the Model
540B have been selected to minimize environmental
sensitivity.
It is suggested that the Model 540B be
given
time enough to arrive at the environmental
temperature before it is used. If the Model 540B
is used before it has arrived at the temperature of
the environment where it is to be used,excessive
thermal drift will be observed making accurate
transfers more difficult.
f. The Model 540B imposes
two load conditions on the
ac source. The ac source sees the 182 ohms/volt
input impedance of the Model 540B when the MODE
switch is in the AC TRANSFER position. When the
MODE
switch is in the OFF or DC TRANSFER
positions, the ac source sees the Model 540B as
an open cir c uit. This impedance change across
the ac source causes a corresponding output level
change from the ac source . When calibrating a
device that
is quite sensitive to level changes, the
user should determine if the ac source level changes
could adversely affect the device. The
user should
take appropriate precautions, such
as switching the
device out of the calibration
circuit before turning
the MODE switch to the OFF or DC positions,
should such a situation arise .
g. Though the internal range selection components and
thermocouple in the Model 540B are protected from
overloads in the voltage mode; no protection is pro-
vided in the current mode or for external shunts or
high frequency converters. These devices are
easily damaged or destroyed by overloads and all
STEP CONTROL POSITION
a POWER REFERENCE
GALVO
SEARCH
540B
possible precautions should be observed. External
switching transients cause many such overloads
and should be avoided. It is possible to damage a
thermal converter without completely destroying it.
One of the characteristics which change, and indi-
cate a damaged thermal element, is de reversal
error. Should the reversal error of any thermal
element change after a suspected overload it is
reasonable to assume that damage has occurred
and the device should be recalibrated.
h. During all transfer measurements the operator
must remain alert to changes in readings regard-
less of their cause. All such changes should be
analyzed and
corrective measures taken, in order
to insure the accuracy of the transfer measure-
ments.
2-11. BATTERY CHECK
2- 12. Use
the procedure of Figure 2-4 to check for
sufficient battery charge each time the instrument is
used.
2-13. DEFLECTION SENSITIVITY
2-14. To determine the percentage
represented by the
GALVANOMETER
at a desired de voltage or current
level applied to the DC INPUT terminals, use the pro -
cedure of Figure 2- 5.
2-15. DC REVERSAL ERROR
2-16. The measurement technique used in the following
procedures does not utilize the de reversal error as
expressed in percent change. However, it is recom-
mended that a de reversal error check be made and re -
corded for future reference, in event that suspected
overload damage has occured to the thermocouple.
This value can be used for comparison, as discussed
in step g of paragraph 2-10. The amount of de reversal
error at a particular input level may be measured as
follows:
a. Apply the
desired de voltage or current to the A54
DC INPUT terminals . Determine the deflection
sensitivity in the HIGH SENSITIVITY position as
described in Figure 2- 5.
b. Adjust the REFERENCE ADJUST controls until a
GALVANOMETER indication of
zero is obtained in
the
HIGH SENSITIVITY position.
c. Set the GALV switch to OPEN.
Depress the PO-
LARITY
switch until it locks and remains in the
depressedposition. Wait approximately 5 seconds;
then
place the GALV switch in the LOCK position.
OPERATION
The PERCENT INPUT
meter must read above the
lower limit of the BAT band on the meter scale in
all BAT CHECK positions.
Figure 2-4. BATTERY CHECK
2-5

540B
STEP CON TROL
POSITION OPERATION
a POWER ON
Set the RANGE switch to succeedingly lower voltage
GALV OPEN ranges until an indication between 50% and 100% is
RANGE 1000v obtained on the PERCENT INPUT meter. When
MODE DC SEARCH
using curren t shunts see parag rap h 2- 24.
b SENSITIVITY LOW
Tap the GALV switch against the spring tension to
MODE DC
TRANSFER MOMENTARY just long enough to see if the GAL-
GALV VANOMETER needle will stay on scale. Adjust the
REFERENCE COARSE COARSE and MEDIUM contr ols until a zero reading
ADJUST MEDIUM
is obtained.
c GALV OP
EN Adjust the GALV ZERO control for a zero re adi ng on
SENSITIVITY ME D
the GALVANOMETER.
GALV ZERO
d GALV LOCK
Adjust the MEDIUM and FINE contro ls for a z er o
REFERENCE reading on the GALVANOMETER.
ADJUST MED IUM
e SENSITIVITY TEST 0.1% Th e GALVANOMETER will deflect to the right by an
amoun t equal to a 0.1 % change in input leve l. This
deflection amount may be used to determ i ne the de -
flection sensitivity (percent per unit of deflection),
which in turn may be used to determine the percent
change r epresented by an on scale GALVANOMETER
deflection as follows :
Deflection Sensitivity = 0· 1%
Dt
%Chan ge = 0·1% Dm
Dt
Dt
=
Th e number of divisions of meter deflection
caused by the operation of the SENS IT IVITY
TEST sw i tch .
Dm =
Th e nu mber of divisions of meter de flection
found in the transfer measur em e nt .
f SENSITIVITY
TES T
OPR
Adjust th e GALV ZERO control for a zero readin g on
GALV OPEN
the GALVANOME TER.
SENSITIVITY HIGH
GALV
ZERO
g GALV LOCK Adjust the FINE contro l for a zero read ing on the
REFERENCE GALVANOMETER.
ADJUST FINE
h SENSITIVITY TEST
0.0 1% The GALVANOMETER will deflect to the right by an
amount equal to a 0. 01% change in input level. This
deflection amount may be used to determine the de -
fl ection sensitivity (perce nt per unit of deflection),
which in turn may be used to determ ine the percent
change represented by an on scale GALVANOMETER
deflection as follows:
Deflection Sensitivity = 0. 01%
Dt
% Change = 0· 01%
Dm
Dt
NOTE:
Deflection sensitivity is improv ed as the level of input more nearl y equals the range s ett ing.
Figure 2 -5 . DEF L ECTION SENSITIVITY
2- 6

540B
STEP
CONTROL POSITION OPERATION
a POWER
ON
Set the RANGE switch to succeedingly lower volt-
GALV
OPEN
age ranges un til an indication between 50% and 100%
SENSITIVITY LOW is obtained
on the PERCENT INPUT meter. (Better
RANGE 1000v
transfer resolution is obtained with readings closer
M OD E
AC SEARCH
to 100% .)
b SENSITIVITY LOW T
ap the GAL V switch against th e spring tension to
MODE AC TRANSFER MOMENTARY
just long enough to see if the GAL-
GALV V ANOMETER
needle will stay on scale. Adjust
REFERENCE
COARSE
th e COARSE and MEDIUM controls until a zero
ADJUST MED IUM
reading is obtained.
c GALV
OP EN Adjust
the GALV ZERO cont r ol for zero reading on
SENSITIVITY
ME D
the GALVANOMETER.
GALV
ZERO
d GALV LOCK Adjust
the MEDIUM and FINE controls for zero
REFERENCE
MED IUM
reading on the GALVANOMETER.
ADJUST FINE
e GALV
OP EN Adj
ust the GALV ZERO control for zero reading on
SENSITIVITY HIGH
the GALVANOMETER.
GALV ZERO
f GALV LOCK
Adjust the FINE control for a zero reading on the
REFERENCE
GALVANOMETER.
ADJUST FINE
g GALV OPEN
SENSITIVITY LOW
h MODE DC SEARCH A
djust th e de source voltage until a reading is
obtained on the P E RCENT INPUT meter t ha t is
equal to the reading noted in step a.
i MODE DC TRANSFER NOTE: DO NOT ADJUST
THE REFERENCE AD-
JUST CONTROLS IN THIS MODE.
j SENSITIVITY LOW
Tap the GAL V switch against the s pring tension to
GALV MOMENTARY
just long enough to see if the GAL-
V AN OMETER needle will s tay on s cale. Adjust
the de source voltage until ze r o is obtained.
k GALV LOCK
Further refine the adjustmen t of the de source volt-
SENSITIVITY MEDIUM
age until zero reading on t he GALVANOMETER is
HIGH
obtained in the HIGH SENSITIVITY position.
l
Recor d th e exact de sourc e voltage.
m R
epeat steps b through l at l east three times or until repeatibility is attained.
R ecord the exact
de voltage .
n
Reverse the input polar i ty to the thermocou ple by depressing the POLARITY switch.
Repeat
steps b through l at least three times or until repeatibility is atta ined.
Record the exact de voltage .
0
The rms value of the unknown ac voltage is equal to the average of the two de voltages recorded in
steps 1 and n.
NOTE:
If a tes t report from a standards laboratory is used ,
calculate the unknown ac voltage from the
following equation:
Eac =(1 +ao Edc
100
Where:
Edc
=
average of two de voltages recorded
ao
=
Eac - Edc
100 =
ac to de percent difference from
Edc
the test report
Figure 2- 6. MEAS URING AN UNKNOWN AC VOLTAGE
2-7

540B
d.
e.
The resulting GALVANOMETER deflection indi-
cates the amount of de reversal error . T he per -
cent change may be computed by multip lying the
deflection
sens i tivity determined in step a by the
amount of de reversal error.
Set the GALV sw i tch to OPEN. Set the POLARITY
switch to
its normal, up, position.
2- 1 7. VOLTA G E M EA S UREM ENT A N D
CALI BRAT
IO N
2- 18. MEASURING AN UNKOWN AC VO LTAGE
2-19. Complete the Battery Check of
Figure 2-4. With
the
RANGE switch in the 1000 volt position an d the MODE
s witch se t to OFF, connect the ac v olt a ge to the AC
IN P UT te r minals and the de so u rce to the DC INPUT
ter mina l s. Use the procedure of F igure 2- 6.
2-2 0. CALIBRATING AN AC V OLT AGE SOURC E
2-21. Complete the Battery Check
of Figure 2- 4. With
the
RANGE switch in the 1000 v olt pos iti on and the MO DE
switch
set to OFF, connect the ac sourc e to th e AC IN-
PUT terminals and the de source to the DC INP UT
terminals. Follow the procedure of Figure 2- 7, for the
calibration of an ac voltage source .
If a test report from a standards laborator y
is used, adjust the de source voltage in step
a to equal 100 times the rms value of
100 + a0
the ac voltage to be calibrated. Where a0
is the ac to de percent difference from the
test report.
2 -2 2. CURRE N T M EAS UREMENT AND
CALIBRATION
2- 23. GENE RA L
2-2 4. A current shunt will not be requ ir ed if the c ur -
rent to be measured or calibrated is 2. 5 to 5 milli-
amperes. The thermocouple of the Model A5 4 is capabl e
of handling this amount of current.
2-25. Current shunts rated up to 30 milliamper es are
plugged directly into the SHUNT terminals of the Model
A54. Current shunts from 50 milliamperes to 5 amperes
are also plugged directly into the SHUNT terminals of
the Model A 54. However, a special retaining screw
(located on the rear panel of the Model A5 4) is used to
secure these larger current shunts to the front pane l of
the Model A54. The Fluke Model A40A Current Shunts,
10 and 20
ampere are connected to the Model A54 with
a
special cable (fluke part number 6002- 212860, illus -
trated in Figure 6-4).
2-26.
To eliminate the process of int e rchanging the
ac and de leads to a current shunt, the Fluke Mod el A45
C
ur r ent Transfer Switch may be use d. Pr o per ca bl es
and con n ect i ons to current shunts in conju nctio n with
the Models A54 and A45 are illus tr at ed in F i gure 2-8 .
2- 8
2-27. Two precautions in regard to lead length and
effects of the Model A45 upon a voltage source should
be
considered.
a. To minimize errors from induced voltages when
connecting a
current shunt or . Mod el A45 to a cir-
cuit under test, use a coaxial cable 30 centimeters
or less in length.
b. Due to the shorting type
transfer switch of the Model
A45, a
current limiting resistor should be placed
in series with a voltage source used as a current
source. If the current limiting resistor is not used
there is a possibility that the voltage source could
be damaged.
2- 28. MEASURING AN UNKNOWN AC CURRENT
2- 2 9. Complete the Battery Check of Figure 2-4. With
a common
commercial ammeter, measure the unknown
current in order to select the proper Model A40 or
Model A40A Current Shunt. If determination of de-
flection sensitivity is desired, refer to Figure 2- 5 and
substitute step a with the following: MODE switch to
OFF,
RANG E switch to SHUNT, GALV switch to OPEN,
and
POWER switch to ON. Follow the procedure of
Figure 2-9, for measurement of an unknown ac current.
The PERCENT INPUT meter of the Model
540B
does not function in the current mode
of operation.
CAUTION
Protectio n from overload is not provided
for the current shunts or the thermocouple
of the Model
A54 when in the SHUNT position
of the
RANGE switch (current mode of oper-
ation).
2-
30. CALIBRATING AN AC CURRENT SOURCE
2-31. Complete
the Battery Check of Figure 2-4. Refer
to
paragraph 2- 23 , for proper shunt selection and con-
nections.
The current shunt selected should be of the
lowest value possible without exceeding
the rated value.
Observe the note and caution of paragraph 2-29. Use
the
procedure of Figure 2-10, for calibrating an ac
current source.
If an A40 or A40A test report is used, adjust
the de source un til the de current equals
100 times the rms value of the ac cur -
100 + a0
rent desired. Where ao is the ac to de per -
cent difference fr om the test report.