Hitachi RAK-35NH5 - Switching power supply for indoor unit; A cycle

(2) Switching power supply for indoor unit
Fig. 4-3 shows the switching power supply circuit for the indoor units.
The switching power supply circuit consists 2 circuits , and is carried on the SW-D-P.W.B.
Fig . 4-2 Voltage specification.
Output name
Output specification Main load circuit
35VÐA
Indoor unit 1 ¥ 2, Reversing valve for A cycle
Electric expansion valve1¥2forAcycle
Control circuit for electric expansion valve of A cycle
Electric expansion valve1¥2forBcycle
Control circuit for electric expansion valve of B cycle
A cycle
Input voltage after
rectification, approx.
325V DC
※ It is supplied via
CN1 from control
P.W.B.
3A, fuse
SW transformer 2
SW transformer 3
B cycle
Fig. 4-3 Switching power supply circuit for indoor unit
The circuit for A cycle generates 35V of the power supply voltage for the indoor unit 1¥ 2, and 12V and 5V for the drive of
electric expansion valve. Similarly . the circuit for B cycle generates 35V of the power supply voltage for the indoor unit3¥4,
and 12V and 5V for the drive of B cycle electric expansion valve. The voltage specification of each output is in fig . 4-2 below.
Indoor unit3¥4(only unit 3 operates for 3 rooms)
BEN 12V Ð A
BEN 5V Ð A
35VÐB
BEN 12V Ð B
BEN 5V Ð B
35 (± 2.5) V
12 (± 2.0) V
5(±0.5) V
35 (± 2.5) V
12 (± 2.0) V
5(±0.5) V
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