Mitsubishi Electric City Multi CMB-P1016NU-G, Service Handbook

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[
IX
Troubleshooting ]
(3) Trouble treatment when the main power breaker is tripped.
Items to be checked Phenomena Remedy
[5]
Check the in-
verter circuit
trouble. Check whether the IPM screw
terminal is not loose. 1) Terminal screws are
loose.
Check for loose IPM terminal
screws and tighten them.
Check the exterior of the IPM. 2) IPM is cracked due to
swelling.
Replace the IPM. Check the oper-
ation in [3] or [4] after replacing the
IPM.
In the case of an output voltage im-
balance or error reoccurrence: Re-
place the G/A board.
In the case of an output voltage
imbalance or error reoccur-
rence after replacement:
Replace the INV board.
Check the resistances between
each terminal of IPM.
Refer to 9.[4].5.(5) for details on
IPM troubleshooting. 3) Check the resistances
between each terminal of
IPM.
Replace the IPM.Check the opera-
tion in [3] or [4] after replacing the
IPM.
In the case of an output voltage im-
balance or error reoccurrence: Re-
place the G/A board.In the case of
an output voltage imbalance or er-
ror reoccurrence after replace-
ment:
Replace the INV board.
4) All normal for items 1) - 3)
above.
Replace the IPM.
In the case of an output voltage im-
balance or error reoccurrence:
Replace the G/A board.In the case
of an output voltage imbalance or
error reoccurrence after replace-
ment:
Replace the INV board.
Items to be checked Phenomena Remedy
[1] Perform Meg check between the
terminals on the power terminal
block TB1. Zero to several ohm, or Meg failure Check each part in the main inverter cir-
cuit.
*Refer to "Simple checking Procedures
for individual components of main in-
verter circuit".
ΠDiode stack
ΠIPM
ΠRush current protection resistor
ΠElectromagnetic relay
ΠDC reactor
ΠNoise filter
[2] Turn on the power again and
check again. 1) Main power breaker trip
2) No remote control display
[3] Turn on the outdoor(heat source)
unit and check that it operates nor-
mally. 1) Operates normally without trip-
ping the main breaker.
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 problem, the compressor
may have a problem.
2) Main power breaker trip A compressor ground fault can be con-
sidered. Go to (2)-[2].