Hitachi RAM-50CNHZ2, Service Manual, Page: 63 / 107

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Model RAM-50CNHZ2
1. Power Circuit
●
This circuit full-wave rectifies 220-230V AC applied between terminals L and N, and boosts it to a required
voltage with the active module, to create a DC voltage.
The voltage becomes 260-380V when the compressor is operated
(1) System power module (SPM2)
(Surrent ACT module, smoothing capacitors
and power module are combined into one
unit)
1
Active module
The active filter, consisting of a reactor
and switching element, eliminates higher
harmonic components contained in the
current generated when the compressor
is operated, and improves the power-
factor.
Smoothing capacitor smoothes voltage,
which has been rectified by diode stack
and boosted at ACT section.
2
Power module section
Refer to item 3 System Power Module
Circuit.
(2) Diode stacks
These rectify the 220-230V AC from
terminals L and N to a DC power supply.
< Reference >
●
In case of malfunction or defective connection:
Immediately after the compressor starts, it may stop
due to “abnormally low speed” active error, etc.
The compressor may continue to operate normally,
but the power-factor will decrease, the operation
current will increase, and the overcurrent breaker
of the household power board will probably activate.
●
In case of active module faulty or defective contact:
Although the compressor continues to operate
normally, the power-factor will decrease, the
operation current will increase, and the overcurrent
breaker of the household power board will probably
activate.
< Reference >
●
If diode bridge 1 is faulty, the compressor may stop
due to “lp”, “abormally low speed”, etc. immediately
after it starts, or it may not operate at all because
no DC voltage is generated between the positive
e
and negative d terminals.
If diode bridge (D25VB60) is faulty, be aware that
the 25A fuse might also have blown.
●
If diode bridge (DS) is faulty, DC voltage may be
not generated and the compressor may not operate
at all. Also, be aware that the 3A fuse might have
blown.
DESCRIPTION OF MAIN CIRCUIT OPERATION (OUTDOOR)
POWER P.W.B.
YEL
BLU
SWITCHING POWER P.W.B.
(FOR INDOOR AND OUTDOOR
P.W.B.)
SWITCHING POWER P.W.B.
(FOR INDOOR P.W.B.)
Fig. 1-1