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4-6
Service Information
Contact potential tests
These tests check the EMF (contact potential) generated by each relay contact pair (HI and
LO) for each channel. The tests use a sensitive digital voltmeter (Model 182) to measure the
contact potential.
Perform the following procedure to check contact potential of each channel.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Connect 1" #22AWG copper jumper wires between the HI and LO terminals of each
channel input (see
Figure
Connect the Model 182 to OUT A HI and LO using the low-thermal cable (see
Figure
4-2).
With the power off, install the scanner card in the Model 2001 Multimeter.
Turn on the Model 2001 and the Model 182 Sensitive Digital Voltmeter. Allow the
Model 182 to warm up for two hours before measurement.
Select the 3mV range on the Model 182.
Select the DCV function on the Model 2001.
Using the CHAN key, close channel 1 (see
procedure).
Verify that the Model 182 reading is <1µV.
Repeat steps 7 and 8 for all 10 channels.
After completing all measurements, turn off the Model 2001 power, remove the scanner
card, and disconnect all jumpers and test leads.
4-2).
"Path resistance tests" on page 4-4
for
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Table of Contents
Troubleshooting
