Mitsubishi Electric CITY MULTI CMB-P1010V-E, Service Handbook

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5) Troubleshooting at breaker tripping
Check items Measures to be taken
1 Check the breaker capacity.
2
Check the a short circuit or grounding in the electrical
system other than the inverter.
3 Check the resistance between terminals on the terminal
block TB1A for power source.
4 Checking by powering again.
5 Operational check by operating air conditioner
The breaker’s capacity should be proper.
Correct any defects.
Check each part inside the inverter power circuit
(resistance, megohm or the like).
a) Diode stack
Refer to “Troubleshooting of diode stack.”
b) Power transistor
Refer to “Troubleshooting of power transistor.”
c) Rush current protection resistor
d) Electromagnetic contactor
e) DC reactor
* For c) ~ e), refer to “Individual Parts Failure Judge-
ment Methods.”
a) As there is a possibility of instantaneous short
circuit generated, find the mark of the short circuit
for repair.
b) When a) is not applicable, the compressor may be
faulty.
The ground fault of inverter output/compressor can
be supposed.
Disconnect the wiring to the compressor and check
the insulation resistance of the following parts with
a megger.
a) Compressor terminals.
b) Inverter output.
1
0 ~ several ohms or improper megohm value
1 Main power source circuit breaker tripping
2 No display of remote controller
1 Normal operation without breaker tripping.
2 Breaker tripping