9-16
Chapter 9 Maintenance and Inspection
9-3 Inspection
Insulation Resistance Test and Withstand Voltage Test
As a rule, do not test the insulation resistance or withstand voltage.
Lightning arrestors are incorporated into the probe and junction box. When these tests are
conducted, the built-in lightning arrestors may be damaged.
If testing must be done, follow the steps below.
(1) Disconnect all of the external wiring completely from each device.
(2) The test locations are shown below. The tests can be conducted with the + and -
terminals of the core wires of the hollow cable, connector terminals, and SUPPLY
terminals shorted.
y
Probe
For the probe with the cable in the hollow pipe : between the core wires (+, -) of the
hollow cable and the shielded wires
For the probe alone : between the connector terminals
(+, -) and the probe case
y
Junction box
Between the SUPPLY terminals (+, -) and the ground terminal of the junction box
(3) The applied voltages and judgment criteria are shown in the table below. To prevent
the meter from being damaged, do not apply a voltage exceeding the value shown
below.
Insulation resistance test Withstand voltage test
Probe and junction box At 25 V DC
20 MΩ or more
50 V AC for 1 minute
Set current 2 mA
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