Fluke 789 Use and care manual

®
789
ProcessMeter
Calibration Manual
PN 1988891
September 2002
© 2002 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

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 three years 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.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
11/99

i
Table of Contents
Title Page
Introduction........................................................................................................ 1
Contacting Fluke................................................................................................ 1
Read First -Safety Information .......................................................................... 2
Warnings and Cautions.................................................................................. 2
Symbols ............................................................................................................. 3
Specifications..................................................................................................... 4
General Specifications................................................................................... 7
Required Equipment .......................................................................................... 7
Basic Maintenance............................................................................................. 8
Cleaning the ProcessMeter............................................................................ 8
Replacing the Batteries.................................................................................. 8
Battery Life.................................................................................................... 9
Checking and Replacing the Fuses................................................................ 10
Calibration Verification..................................................................................... 11
Preparing to Perform Calibration Verification.............................................. 11
Loop Power ................................................................................................... 12
Current Sourcing............................................................................................ 13
Current Measurement.................................................................................... 14
Checking the Diode Test Function................................................................ 15
Checking the Continuity Test Function......................................................... 17
Resistance Measurement Test ....................................................................... 18
DC Millivolts Measurement Test.................................................................. 20
DC Volts Measurement Tests........................................................................ 21
AC Volts Measurement Test ......................................................................... 22
Frequency Measurement Test........................................................................ 23
Calibration Adjustment...................................................................................... 24
Preparing for Calibration Adjustment ........................................................... 24
AC Voltage Adjustment ................................................................................ 25
Frequency Adjustment................................................................................... 26
DC Voltage Adjustment ................................................................................ 27
DC Millivolts Adjustment ............................................................................. 28
Ohms Adjustment.......................................................................................... 28
Diode Adjustment.......................................................................................... 29
Milliamps DC Adjustment............................................................................. 29
Amps DC Adjustment ................................................................................... 30
Amps AC Adjustment ................................................................................... 30
Milliamps Output Adjustment....................................................................... 30
Replacement Parts and Accessories................................................................... 31

789
Calibration Manual
ii

iii
List of Tables
Table Title Page
1. Symbols.................................................................................................................. 3
2. Required Equipment and Software......................................................................... 8
3. Typical Alkaline Battery Life ................................................................................ 9
4. Current Sourcing Test ............................................................................................ 13
5. DC mA Test ........................................................................................................... 15
6. DC Amp Test ......................................................................................................... 15
7. AC Amp Test ......................................................................................................... 15
8. Resistance Measurement Test Using a 5500A or 5520A Calibrator...................... 19
9. DC mV Test ........................................................................................................... 20
10. DC Volts Test......................................................................................................... 22
11. AC Volts Test......................................................................................................... 22
12. Frequency Measurement Test ................................................................................ 23

789
Calibration Manual
iv

v
List of Figures
Figure Title Page
1. Replacing the Batteries and Fuses.......................................................................... 9
2. Verifying Loop Power............................................................................................ 12
3. Current Sourcing Connections Using the HP 3458A............................................. 13
4. Current Measurement Test Connections................................................................ 14
5. Diode Test Connections......................................................................................... 16
6. Continuity Test Connections.................................................................................. 17
7. Resistance Measurement Test Connections........................................................... 18
8. DC mV Measurement Test Connections................................................................ 20
9. AC/DC Voltage Measurement Test Connections .................................................. 21
10. Frequency Measurement Test Connections ........................................................... 23
11. Calibration Button Access...................................................................................... 26
12. Replacement Parts.................................................................................................. 31

789
Calibration Manual
vi

1
789 ProcessMeter
Introduction
WXWarning
The information provided in this manual is for the use of qualified
personnel only. Do not perform the calibration verification tests or
calibration procedures described in this manual unless you are
qualified to do so.
WCaution
The 789 ProcessMetercontains parts that can be damaged by static
discharge. No procedure in this document requires the case to be
opened. If you do so, follow the standard practices for handling static
sensitive devices.
The Calibration Manual for the 789 ProcessMeter (hereafter, also referred to as “the
ProcessMeter” or “the UUT”) provides the following information:
•Precautions and Safety information
•Specifications
•Basic maintenance (cleaning, replacing the batteries and fuses)
•Calibration verification test procedures
•Calibration adjustment procedures
•Accessories and replaceable parts
For complete operating instructions, refer to the 789 ProcessMeter Users Manual (on the
CD-ROM provided).
Contacting Fluke
To contact Fluke, call:
USA : 1-888-99-FLUKE (1-888-993-5853) Canada: 1-800-36-FLUKE (1-800-363-5853)
Europe: [phone] Japan: [phone]
Singapore: [phone] Anywhere in the world: [phone]
Address correspondence to:
Fluke Corporation Fluke Europe B.V.
P.O. Box 9090, P.O. Box 1186,
Everett, WA 98206-9090 5602 BD Eindhoven
USA The Netherlands
Or visit us on the World Wide Web: www.fluke.com

789
Calibration Manual
2
Read First -Safety Information
Warnings and Cautions
In this manual, a Warning identifies conditions and actions that pose hazard(s) to the
user; a Caution identifies conditions and actions that may damage the ProcessMeter or
the test instruments.
WXWarning
To avoid possible electric shock or personal injury:
•Do not use the ProcessMeter if it looks damaged.
•Examine the ProcessMeter before use. Look for cracks in the case,
missing plastic, or damaged insulation around the connectors.
•Inspect the test leads for damaged insulation or exposed metal.
Check for test lead continuity. Replace damaged test leads.
•Do not use the ProcessMeter if it operates abnormally. Protection
provided by the ProcessMeter may be impaired. When in doubt,
have the ProcessMeter serviced.
•Do not apply more than the rated voltage as marked on the
ProcessMeter between terminals or between any terminal and
earth ground.
•When using probes, keep fingers behind the finger guards on the
probes.
•Use caution when working above 30 V ac rms, 42 V ac peak, or
60 V dc. Such voltages pose a shock hazard.
•Connect the common lead (COM) before connecting the live test
lead. When disconnecting test leads, disconnect the live test lead
first.
•Remove test leads from the ProcessMeter before opening the
battery compartment door.
•Do not operate the ProcessMeter around explosive gas, vapor, or
dust.
•During normal operation, use only type AA batteries, properly
installed in the ProcessMeter case, to power the ProcessMeter.
•Make sure the battery compartment door is closed and latched
before you operate the ProcessMeter.
•During calibration adjustment, use only specified calibration
equipment listed in Table 2.
•When servicing the ProcessMeter, use only specified replacement
parts.
•Before measuring current, check the ProcessMeter’s fuses, see
“Checking and Replacing the Fuses”
.
•To avoid false readings, which can lead to possible electric shock
or personal injury, replace the batteries as soon as the low battery
indicator (M) appears.

789 ProcessMeter
Symbols
3
WCaution
To avoid possible damage to the ProcessMeter or the test equipment:
•Disconnect the power and discharge all high voltage capacitors
before testing resistance, diodes, or continuity.
•Use the proper terminals, switch setting, and range for the
measurement or sourcing applications.
Symbols
Symbols used on the ProcessMeter and in this calibration manual are explained in
Table 1.
Table 1. Symbols
Symbol Meaning Symbol Meaning
Alternating current Earth ground
Direct current Fuse
Alternating or direct current Conforms to European Union
directives
Risk of danger. Important
information. See manual. Conforms to relevant Canadian Standards Association directives
Battery TDouble insulated
Listed
950 Z
Meets Underwriters’
Laboratories safety
requirements
Inspected and licensed by TÜV
Product Services
CAT III Overvoltage (Installation)
Category III, Pollution Degree 2
per EN61010 refers to the level
of Impulse Withstand Voltage
protection provided. Typical
locations include: mains, wall
outlets, main distribution levels
connected closer to the supply
system but less than the primary
supply system (CAT IV).
N10140
Conforms to relevant Australian
standards

789
Calibration Manual
4
Specifications
All specifications apply from +18 °C to +28 °C unless stated otherwise.
All specifications assume a 5-minute warm-up period.
The standard specification interval is 1 year.
Note
“Counts” refers to the number of increments or decrements of the least
significant digit.
DC Volts Measurement
Range (V dc) Resolution Accuracy, ±(% of Reading + Counts)
4.000 0.001 V 0.1 % + 1
40.00 0.01 V 0.1 % + 1
400.0 0.1 V 0.1 % + 1
1000 1 V 0.1 % + 1
Input impedance: 10 M Ω (nominal), < 100 pF
Normal mode rejection ratio: > 60 dB at 50 Hz or 60 Hz
Common mode rejection ratio: > 120 dB at dc, 50 Hz, or 60 Hz
Overvoltage protection: 1000 V
DC Millivolts Measurement
Range (mV dc) Resolution Accuracy, ±(% of Reading + Counts)
400.0 0. 1 mV 0.1 % + 2
AC Volts Measurement
Range (ac) Resolution Accuracy, ±(% of Reading + Counts)
50 Hz to 60 Hz 45 Hz to 200 Hz 200 Hz to 500 Hz
400.0 mV 0.1 mV 0.7 % + 4 1.2 % + 4 7.0 % + 4
4.000 V 0.001 V 0.7 % + 2 1.2 % + 4 7.0 % + 4
40.00 V 0.01 V 0.7 % + 2 1.2 % + 4 7.0 % + 4
400.0 V 0.1 V 0.7 % + 2 1.2 % + 4 7.0 % + 4
1000 V 1 V 0.7 % + 2 1.2 % + 4 7.0 % + 4
Specifications are valid from 5 % to 100 % of amplitude range.
AC conversion: true rms
Maximum crest factor: 3 (between 50 and 60 Hz)
For non-sinusoidal waveforms, add
± (2 % reading + 2 % f.s.) typical
Input impedance: 10 M
Ω (nominal), < 100 pF, ac-coupled
Common mode rejection ratio: > 60 dB at dc, 50 Hz, or 60 Hz

789 ProcessMeter
Specifications
5
AC Current Measurement
Range
45 Hz to 2 kHz Resolution Accuracy, ±(% of Reading + Counts) Typical Burden Voltage
1.000 A (Note) 0.001 A 1 % + 2 1.5 V/A
Note: 440 mA continuous, 1 A 30 seconds maximum
Specifications are valid from 5 % to 100 % of amplitude range.
AC conversion: true rms
Maximum crest factor: 3 (between 50 and 60 Hz)
For non-sinusoidal waveforms, add
± ( 2 % reading + 2 % f.s.) typical
Overload protection 440 mA, 1000 V fast-blow fuse
DC Current Measurement
Range Resolution Accuracy
±(% of Reading + Counts) Typical Burden Voltage
30.000 mA 0.001 mA 0.05 % + 2 14 mV/mA
1.000 A (Note) 0.001 A 0.2 % + 2 1.5 V/A
Note: 440 mA continuous, 1 A 30 seconds maximum
Overload protection: 440 mA, 1000 V fast-blow fuse
Ohms Measurement
Range Resolution Measurement Current Accuracy
±(% of Reading + Counts)
400.0 Ω0. 1 Ω220 µA 0.2 % + 2
4.000 kΩ0.001 kΩ60 µA 0.2 % + 1
40.00 kΩ0.01 kΩ6.0 µA 0.2 % + 1
400.0 kΩ0.1 kΩ600 nA 0.2 % + 1
4.000 MΩ0.001 MΩ220 nA 0.35 % + 3
40.00 MΩ0.01 MΩ22 nA 2.5 % + 3
Overload protection: 1000 V
Open circuit voltage: < 3.9 V
Frequency Counter Accuracy
Range Resolution Accuracy
±(% of Reading + Counts)
199.99 Hz 0.01 Hz 0.005 % + 1
1999.9 Hz 0.1 Hz 0.005 % + 1
19.999 kHz 0.001 kHz 0.005 % + 1
Display updates 3 times/second at > 10 Hz

789
Calibration Manual
6
Frequency Counter Sensitivity
Minimum Sensitivity (rms Sinewave)
5 Hz to 5 kHz*
Input Range
AC DC
(approximate trigger level 5 % of full scale)
400 mV 150 mV (50 Hz to 5 kHz) 150 mV
4 V 1 V 1 V
40 V 4 V 4 V
400 V 40 V 40 V
1000 V 400 V 400 V
*Usable 0.5 Hz to 20 kHz with reduced sensitivity.
10
6
VHz max
Diode Test and Continuity Test
Diode test indication: Displays voltage drop across device, 2.0 V full scale. Nominal
test current 0.2 mA at 0.6 V. Accuracy ±(2 % + 1 count).
Continuity test indication: Continuous audible tone for test resistance < 100 Ω
Open circuit voltage: < 2.9 V
Short circuit current: 220 µA typical
Overload protection: 1000 V rms
Loop Power Supply
Loop Power Supply: Minimum 24 V@ 24 mA into 1200 Ωload
DC Current Output
Source mode:
Span: 0 mA or 4 mA to 20 mA, with overrange to 24 mA
Accuracy: 0.05 % of span1 (span: 0 to 20 mA)
Compliance voltage: 28 V with battery voltage > ~4.5 V
10.1 x specified accuracy per °C for temperatures < 18 °C or > 28 °C
Simulate Mode:
Span: 0 mA or 4 mA to 20 mA, with overrange to 24 mA
Accuracy: 0.05 % of span1 (span: 0 to 20 mA)
Loop voltage: 24 V nominal, 48 V maximum, 15 V minimum
Compliance voltage: 21 V for 24 V supply
Burden voltage: < 3 V
10.1 x specified accuracy per °C for temperatures < 18 °C or > 28 °C

789 ProcessMeter
Required Equipment
7
General Specifications
Maximum voltage applied between any jack and earth ground: 1000 V
Storage temperature: -40 °C to 60 °C
Operating temperature: -20 °C to 55 °C
Operating altitude: 2000 meters maximum
Temperature coefficient: 0.05 x specified accuracy per °C for temperatures
< 18 °C or > 28 °C
Accuracy adders for use in RF Fields: In an RF field of 3 V/m, change the accuracy
specifications as follows:
For AC Volts Measurement, add 0.25 % of range
For DC Current Measurement, 30.000 mA range, add 0.14 % or range
For DC Current Output, add 0.32 % of span
Accuracy for all ProcessMeter functions is not specified in RF fields > 3 V/m.
Relative humidity: 95 % up to 30 °C, 75 % up to 40 °C, 45 % up to 50 °C, and 35 % up
to 55 °C
Vibration: Random 2 g, 5 to 500 Hz
Shock: 1 meter drop test
Safety: Complies with EN61010, ANSI/ISA S82.01-1994 and CAN/CSA C22.2
No. 1010.1-92 Overvoltage Category III.
Certifications: , ,,
Power requirements: Four AA batteries (alkaline recommended)
Size: 10.0 cm X 20.3 cm X 5.0 cm (3.94 in X 8.00 in X 1.97 in)
Weight: 610 g (1.6 lbs)
Required Equipment
Equipment and software required to perform the procedures in this manual are identified
in Table 2.
If the recommended equipment model is not available, in some cases other equipment
can be substituted as long as it meets the specifications indicated.
WXWarning
To avoid safety hazards and equipment damage during the calibration
procedure, use the specified calibration equipment listed in Table 2.
Using unspecified equipment can jeopardize the calibration
verification test and pose safety hazards.
Note
Unless otherwise indicated, all connection diagrams for the calibration
verification tests in this manual showing a calibrator or digital multimeter
use a Fluke 5500A calibrator or Agilent 3458A.
If you are using a different calibrator or DMM, make the connections
appropriate for that instrument.

789
Calibration Manual
8
Table 2. Required Equipment and Software
Equipment Minimum Specifications Recommended Model
Calibration Source No Substitute Fluke Model 5500A
Digital Process Meter or
Digital Process Calibrator No Substitute Fluke 787 ProcessMeter 741,743, or 744 Process Calibrator
Digital Multimeter No Substitute Agilent 3458A
Test Leads, low leakage,
RG-58/U type Leakage resistance >than 1.0 x 1013
Ωat 45 °C and 75 % relative humidity Fluke 5440A-7002 Low Thermal Test Leads
Basic Maintenance
Cleaning the ProcessMeter
WXWarning
To avoid electrical shock or damage, never allow water inside the case
of the ProcessMeter.
If the ProcessMeter requires cleaning, wipe it down with a cloth that is lightly dampened
with water or a mild detergent.
WCaution
Do not use aromatic hydrocarbons, chlorinated solvents, or methanol-
based fluids when wiping down the ProcessMeter. To avoid damaging
the case, never apply solvents to the case of the ProcessMeter.
Replacing the Batteries
WXWarning
To avoid electrical shock:
•Remove test leads from the ProcessMeter before opening the
battery compartment door.
•Close and latch the battery compartment door before using the
ProcessMeter.
Replace the batteries as follows. Refer to Figure 1. Use four AA alkaline batteries.
1. Remove the test leads and turn the ProcessMeter OFF.
2. With a standard blade hand screwdriver, turn each battery compartment door screw
counterclockwise so that the slot is parallel with the screw picture molded into the
case.
3. Lift off the battery compartment door.
4. Remove the ProcessMeter’s batteries.
5. Replace with four new AA alkaline batteries.
6. Reinstall the battery compartment door and tighten screws.

789 ProcessMeter
Basic Maintenance
9
F2
F1
anw037.eps
Figure 1. Replacing the Batteries and Fuses
Battery Life
WXWarning
To avoid false readings, which can lead to possible electric shock or
personal injury, replace the batteries as soon as the low battery
indicator (M) appears.
The ProcessMeter is powered by four AA alkaline batteries.
Table 3 shows typical alkaline battery life. To preserve battery life:
•Use current simulation instead of sourcing when possible.
•Avoid using the backlight.
•Do not disable the automatic power-off feature.
•Turn the ProcessMeter off when not in use.
Table 3. Typical Alkaline Battery Life
ProcessMeter Operation Hours
Measuring any parameter 140
Simulating Current 140
Sourcing 12 mA into 500 Ω10

789
Calibration Manual
10
Checking and Replacing the Fuses
WXWarning
To avoid personal injury or damage to the ProcessMeter, use only the
specified replacement fuse, 440 mA 1000 V fast-blow, Fluke PN
943121.
Both current input jacks are fused with separate 440 mA fuses. To determine if a fuse is
blown:
1. Turn the rotary function switch to W.
2. Plug the black test lead into COM, and the red test lead into the Acinput.
3. Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the
resistance is about 1 Ω, the fuse is good. An open reading means that fuse F1 is
blown.
4. Move red test lead to ^.
5. Using an ohmmeter, check the resistance between the ProcessMeter test leads. If the
resistance is about 14 Ω, the fuse is good. An open means that fuse F2 is blown.
If a fuse is blown, replace it as follows. Refer to Figure 1 as necessary:
1. Remove the test leads from the ProcessMeter and turn the ProcessMeter OFF.
2. With a standard blade hand screwdriver, turn each battery compartment door screw
counterclockwise so that the slot is parallel with the screw picture molded into the
case.
3. Remove either fuse by gently prying one end loose, then sliding the fuse out of its
bracket.
4. Replace the blown fuse(s).
5. Replace the battery compartment door. Secure the door by turning the screws one-
quarter turn clockwise.

789 ProcessMeter
Calibration Verification
11
Calibration Verification
WXWarning
Some of the calibration verification tests involve the use of high
voltages and should be performed by qualified personnel only.
To avoid electrical shock, always place the calibrator in the Standby
(STBY) mode between tests and before handling the test connections
or test cables.
Calibration verification tests confirm the complete functionality of the ProcessMeter and
check the accuracy of each ProcessMeter function against its specifications. If the
ProcessMeter fails any calibration verification test, it needs calibration adjustment or
repair.
The ProcessMeter’s performance and accuracy are specified for one year after
calibration at operating temperatures of +18 °C to +28 °C (64 °F to 82 °F), in relative
humidity to 90 %. The specifications assume the ProcessMeter has been warmed up for 5
minutes before use.
To perform the calibration verification tests, it is not necessary to open the case; no
adjustments are necessary. Merely make the required connections, source the designated
values, and determine if the reading on the ProcessMeter or the multimeter falls within
the acceptable range indicated.
These calibration verification test procedures assume that the person performing the tests
has read the 789 Users Manual, knows how to select functions and ranges on the
ProcessMeter, and knows how to operate the required equipment.
Note
Calibration verification tests for the ProcessMeter can be performed
manually, or they can be computer-automated (using Fluke’s MET/CAL
Calibration Software). This document provides the procedures necessary to
perform the calibration verification test manually.
Preparing to Perform Calibration Verification
Note
Throughout the calibration verification tests, “UUT” (unit under test)
refers to the ProcessMeter; the word “multimeter” is reserved for the
digital multimeter identified in the required equipment listed in Table 2.
Unless otherwise indicated, all connection diagrams for the calibration
verification tests in this manual showing a calibrator or digital multimeter
use a Fluke 5500A calibrator or HP 3458A.
If using a different calibrator or DMM make the connections appropriate
for your instrument.
To prepare the UUT for the calibration verification tests:
1. Make sure that the required equipment is available (see Table 2).
2. Make sure that the fuses in the UUT are intact. See “Checking and Replacing a
Fuse” earlier in this manual.
3. Make sure the UUT has fresh batteries. See “Replacing the Batteries” earlier in this
manual.

789
Calibration Manual
12
4. Warm up the calibrator and multimeter as required by their specifications.
5. Remove all input cables from the front of the UUT.
6. Make sure that the UUT is in a stable ambient temperature between 18 °C and 28 °C
(64.4 °F and 82.4 °F) and that it has been warmed up for 5 minutes.
Loop Power
1. Connect the UUT SOURCE + (AD)terminal to the SIMULATE + (FmA) jack of the
789.
2. Connect the UUT SOURCE - (mAF)terminal to the SIMULATE - (COM) jack of the
787.
3. Enable the dc volts autorange function of the HP3458A multimeter.
4. Connect the voltage input terminals of the multimeter to the SOURCE + and
SOURCE - terminals of the UUT as shown in Figure 2.
5. Select the OUTPUT Zrotary position of the 787 multimeter and turn the rotary
knob of the UUT to LOOP POWER (the UUT provides loop power and acts as a
current source).
6. Use the % STEP key on the 787 to simulate 24 mA.
7. Verify that the voltage read by the multimeter is greater than 30 V.
8. Push J(BLUE) on the 789 to switch to its internal 250 Ω.
9. Verify that the voltage read by the multimeter is greater than 24 V.
mA
mA
mA
mA
mV
V
V
A
LOOP POWER
250
HART
OFF
mA
ACOM
V
0%
RANGE HOLD
REL
MIN MAX
%STEP COARSE FINE
SpanCheck
Hz
100%
789
PROCESSMETER
HP 3458A
DC Volts Autorange
Function
UUT
OFF
AmA COM V
1000V
30mA
FUSED
0.44A
(1A /30 sec)
FUSED
mA
mA
A
mA
OUTPUT 0-24mA
SOURCE SIMULATE
+ +
% STEP COARSE FINE
mV
V
V
OUTPUT
CAT
787
PROCESSMETER
MIN MAX RANGE HOLD
H
REL Hz
adm006F.EPS
Figure 2. Verifying Loop Power