Hitachi SJ300 Series Megger Test

		SJ300 Inverter	6–11
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, P, N, RB, U, V, and W]. Most importantly, the
		input power and motor wires will be disconnected from the inverter.
	4.	Remove the jumper at connector J61. It is located on the main circuit board beside the
		power terminals.
	5.	Use a bare wire and short terminals [R, S, T, PD, P, N, RB, U, V, and W] together as shown
		in the diagram.
	6.	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 5MΩ or greater resistance.

						Add test
					jumper wire
Disconnect			SJ300
power source							Disconnect
L1		R		U			motor wires
L2		S		V					Motor
L3		T		W
				P
								Megger, 500VDC
		J61		PD
				RB
Disconnect jumper at
				N
J61 before performing		Earth
	the megger test	GND

7.After completing the test, disconnect the megger from the inverter.

8.Reconnect the jumper at connector J61 as before.

9.Reconnect the original wires to terminals [R, S, T, PD, P, N, RB, 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.

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