Hitachi WJ200 Series Software, Instruction Manual

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Megger test
The
megger
is a piece of test equipment that uses a high voltage to determine if an
insulation degradation has occurred. For inverters, it is important that the power
terminals be isolated from the Earth GND terminal via the proper amount of
insulation.
The circuit diagram below shows the inverter wiring for performing the megger test.
Just follow the steps to perform the test:
1. Remove power from the inverter and wait at least 5 minutes before proceeding.
2. Open the front housing panel to access the power wiring.
3. Remove all wires to terminals [R, S, T, PD/+1, P/+, N/–, U, V, and W]. Most
importantly, the input power and motor wires will be disconnected from the inverter.
4. Use a bare wire and short terminals [R, S, T, PD/+1, P/+, N/–, U, V, and W] together
as shown in the diagram.
5. Connect the megger to the inverter Earth GND and to the shorted power terminals
as shown. Then perform the megger test at 500 VDC and verify 5M Ω or greater
resistance.
6. After completing the test, disconnect the megger from the inverter.
7. Reconnect the original wires to terminals [R, S, T, PD/+1, P/+, N/–, U, V, and W].
CAUTION: Do not connect the megger to any control circuit terminals such as
intelligent I/O, analog terminals, etc. Doing so could cause damage to the inverter.
CAUTION: Never test the withstand voltage (HIPOT) on the inverter. The inverter has
a surge protector between the main circuit terminals above and the chassis ground.
CAUTION: Power terminal assignment is different compared to old models such as
L100, L200 series, etc,. Pay attention when wiring the power cable.
WJ200