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Chapter6
6.3 Ground Resistance Test with a Megger
When testing an external circuit with a megger, disconnect all the external circuit cables from the inverter to prevent it
from being exposed to the test voltage.
Use a tester (in high-resistance range mode) for a conduction test on the control circuit. Do not use a megger or buzzer
for that purpose.
Apply the ground resistance test using a megger only to the main circuit of the inverter. Do not carry out the test using
a megger for its control circuit.
Use a 500 VDC megger for the ground resistance test.
Before the main circuit test with a megger, remove the jumper for switching the inverter's internal filter function, and
then connect terminals R, S, T, U, V, W, P, PD, N, RB, R0, and T0 by wires as shown in the figure below. Subsequently,
carry out the test.
After the test using the megger, remove the wires from terminals R, S, T, U, V, W, P, PD, N, RB, R0, and T0, and connect
the jumper for switching the inverter's internal filter function at the original position.
Note that only inverter models with a capacity of less than 22 kW have the RB terminal.
Power supply
Do not connect
power supply cables
to the inverter.
500 VDC megger
6.4 Withstand Voltage Test
Do not carry out a withstand voltage test for the inverter. The test may damage its internal parts or cause them to
deteriorate.
Maintenance and Inspection
P
PD
N
R
R
B
S
T
Ground
Ground
terminal
terminal
R0
T0
Be sure to remove the jumper for
switching the internal filter function.
6-3
Motor
U
IM
V
W
Do not connect the
inverter cables to the
motor.
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