Insulation Test - IMO Jaguar CUB Instruction Manual

7.4 Insulation Test

Because an insulation test is made in the factory before shipment, avoid a Megger test.
If a Megger test is unavoidable, follow the procedure below. Because a wrong test procedure will
cause breakage of the inverter, take sufficient care.
A dielectric strength test will cause breakage of the inverter similarly to the Megger test if the test
procedure is wrong. When the dielectric strength test is necessary, contact the Company where you
purchased the product or contact IMO.
(1) Megger test of main circuit
1) Use a 500 VDC Megger and shut off the main power supply without fail during measurement.
2) If the test voltage leaks to the control circuit due to the wiring, disconnect all the control wiring.
3) Connect the main circuit terminals with a common cable as shown in Figure 7.2.
4) The Megger test must be limited to across the common line of the main circuit and the ground
terminal ( G ).
5) 5 M (1 M for the EMC filter built-in type of inverters) or a larger value displayed at the Megger
indicates a correct state. (The value is for a discrete inverter.)
(2) Dielectric strength
test of control circuit
Do not perform a Megger test or dielectric strength test for the control circuit. Prepare 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. 1 M or a larger measurement indicates a correct state.
(3) Dielectric strength
test of external main circuit and sequence control circuit
Disconnect all the inverter terminals so that the test voltage is not applied.
Figure 7.2 Megger Test
7-7