Solutions For The Main No-Fuse Breaker Trip; Solutions For The Main Earth Leakage Breaker Trip - Mitsubishi Electric R410A Service Handbook

[8-9 Troubleshooting Inverter Problems (TLMU) ]
8-9-11

Solutions for the Main No-Fuse Breaker Trip

Items to be checked
[1] Perform Meg check be-
tween the terminals on the
power terminal block TB1.
[2] Turn on the power again
and check again.
[3] Turn on the outdoor unit
and check that it operates
normally.
8-9-12

Solutions for the Main Earth Leakage Breaker Trip

Items to be checked
[1] Check the earth leakage breaker
capacity and the sensitivity cur-
rent.
[2] Check the resistance at the power
supply terminal block (TB1) with a
megger.
[3] Disconnect the compressor wir-
ings and check the resistance of
the compressor with a megger.
[4] Disconnect the fan motor wirings
and check the resistance of the fan
motor with a megger.
The insulation resistance could go down to close to 1M after installation or when the power is kept off for an extended period
of time because of the accumulation of refrigerant in the compressor. If the earth leakage breaker is triggered, please use the
following procedure to take care of this.
Disconnect the wires from the compressor's terminal block.
If the resistance is less than 1 M , switch on the power for the outdoor unit with the wires still disconnected.
Leave the power on for at least 12 hours.
Check that the resistance has recovered to 1 M or greater.
Earth leakage current measurement method
For easy on-site measurement of the earth leakage current, enable the filter with a measurement instrument that has filter
functions as below, clamp all the power supply wires, and measure.
Recommended measurement instrument: CLAMP ON LEAK HiTESTER 3283 made by HIOKI E.E. CORPORATION
When measuring one device alone, measure near the device's power supply terminal block.
HWE14080
Phenomena
Zero to several ohm, or Meg failure a. Check each part in the main inverter circuit.
1) Main power breaker trip
2) No remote control display
1) Operates normally without tripping
the main breaker.
2) Main power breaker trip
Phenomena
Use of a non-specified earth
leakage breaker
Failure resistance value
Failure compressor if the insu-
lating resistance value is not in
specified range.
Failure when the insulating re-
sistance value is 1 M or less.
Failure fan motor if the insulat-
ing resistance value is not in
specified range.
Failure when the insulating re-
sistance value is 1 M or less.
- 271 -
Remedy
Refer to the following page(s). [8-9-13 Sim-
ple Check on Inverter Circuit Compo-
nents](page 272)
Diode stack
IPM
IGBT module
Rush current protection resistor
Electromagnetic relay
DC reactor
b. A compressor ground fault can be consid-
ered. Go to 8-9-3.
a) The wiring may have been short-circuited.
Search for the wire that short-circuited, and
repair it.
b) If item a) above is not the cause of the prob-
lem, the compressor may have a problem.
A compressor ground fault can be considered.
Go to 8-9-3.
Remedy
Replace with a regulation earth leakage
breaker.
Check each part and wiring.
Refer to the following page(s). [8-9-13 Sim-
ple Check on Inverter Circuit Compo-
nents](page 272)
IPM
IGBT module
Rush current protection resistor
Electromagnetic relay
DC reactor
Check that there is no liquid refrigerant in
the compressor. If there is none, replace
the compressor.
Replace the fan motor.
GB