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Model 6517B Electrometer Reference Manual
Cable insulation resistance test
This test is used to measure the insulation resistance of a cable. The below figure shows the
connections for this test. The resistance of the insulator between the shield and the inner conductor is
being measured. The cable sample should be kept as short as possible to minimize input capacitance
to the ammeter.
For this test a fixed voltage (BIAS V) is applied across the insulator for a specified time to allow the
charging effects of cable capacitance to stabilize. The resistance is then measured and stored in the
buffer. This test is selected and configured from the CONFigure SEQUENCE menu (DEV-CHAR;
CABLE).
Resistor voltage coefficient test
High valued resistors often have a change in resistance with applied voltage. This change in
resistance is characterized as the voltage coefficient. Voltage coefficient is defined as the percent
change in resistance per unit change in applied voltage:
6517B-901-01 Rev. C / August 2015
Figure 70: Cable insulation resistance test connections
Figure 71: Voltage coefficient formula
Section 6: Test sequences
6-5
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