Chapter 6 Maintenance and Inspection
6 - 3
Increase the voltage to 90% and keep for 1 hour.
Then apply rated voltage for 5 hours.
*5 In case fan is locked by dust or particle, it takes 5 to 10 seconds to restart even after the dust is removed.
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.
IM
R
S
T
U
V
W
PP NR
R0
T0
Power suppl
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