7.6 Insulation Test
7-13
MAINTENANCE AND INSPECTION
7.6 Insulation Test
Since the inverter has undergone an insulation test before shipment, avoid making a Megger test at the customer’s
site.
If a Megger test is unavoidable for the main circuit, observe the following instructions; otherwise, the inverter may
be damaged. A withstand voltage test may also damage the inverter if the test procedure is wrong.
As with the megger test, performing a withstand voltage test incorrectly may damage the product. When the
withstand voltage test is necessary, consult your Fuji Electric representative.
7.6.1 Megger test of main circuit
1) Use a 500 V DC megohmmeter, and be sure to measure with the main power turned OFF.
2) If the test voltage is also applied to the control circuit due to the way in which the system is wired, disconnect
all connections to the control circuit.
3) Connect the main circuit terminals with common wire as shown in Fig. 7.6-1.
(Terminals [R0] and [T0] can be found on the FRN0008G2S-2G/FRN0004G2□-4G or above.)
4) Perform the megger test only across the main circuit common wires and ground ( ).
5) The result is normal if the megohmmeter reads 5 MΩ or higher. (The value is measured on the inverter
alone.)
Fig. 7.6-1 Main circuit terminal connection for Megger test
7.6.2 Insulation test of control circuit
Do not make a Megger test or withstand voltage test for the control circuit. Use a high resistance range tester for
the control circuit.
1) Disconnect all the external wiring from the control circuit terminals.
2) Perform a continuity test to the ground. The result is normal if the reading is 1 MΩ or higher.
7.6.3 Insulation test of external main circuit and sequence control circuit
Disconnect all the wiring connected to the inverter so that the test voltage is not applied to the inverter.
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