SWITCH/SWITCHED CONTACTS RESISTANCE MEASUREMENT PROCEDURES

StepExpected Result/Action
NOTE: Steps 5 and 6 test switches and contactor/relay contacts using the
resistance (continuity) check method.
5. Turn power off, then discharge all capacitors in the circuit. Disconnect at least
one lead of the switch or contacts from the circuit.
Power is off in preparation for the resistance measurement.
6. Set up the VOM/DMM to measure resistance. If using a VOM, select the R x 1
range.
Connect the VOM/DMM across the switch or contacts as shown in Figure
SP-8-8. Measure the resistance.
If the VOM/DMM shows an infinite resistance reading, the switch/switched
contacts are open.
If the VOM/DMM shows a short (zero resistance) reading, the switch/switched
contacts are closed.
If the VOM/DMM shows a measurable resistance, the switch contacts are neither
fully open or closed or some other problem exists. This condition is not permitted
and the device should be replaced.

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