Hitachi RAS-60YH5 Service Manual page 71

5V
Reset circuit
Over-load external
setting circuit
DC 260V
-360V
Current amplified
circuit
The following describes the operations of each circuit in detail.
G
(1) Peak current cut off circuit
Fig.8-3 Peak Current Cut off Circuit and Waveforms at Each Section.
DC current Id
(27A)
Voltage at point
A
(1.35V)
Voltage at point
B
The Ip cut off circuit detects an instantaneous excessive current and stops inverter to protect parts such
G
as SPM2, etc.
As shown in diagram, if current exceeding 27A flows, voltage at point
G
is input to pin
10
threshold of IC1 is exceeded in this case, Lo signal is input from pin
signal is input to pin
When drive output from microcomputer is stopped, all drive output goes Hi, and microcomputer is initialized
G
to enter drive signal standby mode. 3 minutes later, microcomputer outputs drive signal again, to start
operation.
Reset Voltage
Chopper
signal
DC
Current
level
–
Negative
Terminal
DC
current
A
Detection
resistor
0V
of SPM2 – HIC, and voltage divided by R41 and R43 is input to pin
of microcomputer, microcomputer stops drive output.
17
Chopper
signal
Circuit
IP signal
Peak current
cut off circuit
Detection
resistor
Fig. 8-2
SPM2 – HIC
IC1
R41
9 9
0V 0V
Fig.8-3
– 83 –
Drive
signal
Drive
Power
module
DC current
SPM2 Main P.W.B
B
CN14
R42
20 9 2
8
F
QC
recognized by detecting resistor
A
(Voltage at point
8
Compressor
motor
HIC
39 17
IP
Outdoor
microcomputer
of IC1. Since
9
. When Lo
B