Hitachi RAC-25CNH2, Руководство по обслуживанию, Страница: 59 / 81

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–
+
–
+
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35
36
38
Detection
resister
R24
DC current
OPI
R1
R2
0V
43
60
61
60
59
39
Is
6
5
R3
R4
0V
D002
0V 0V
R038 C031
7
R5
0V 0V
R508
R507
8J-HIC
Vd
Id
Is
Micro
computer
HIC
5V
0V
Fig. 8-6
Fig. 8-7
(260-360V)
C515
Voltage at micro computer pin
Rotation speed of compressor
Deceleration Deceleration Acceleration Acceleration
Commanded rotation speed
Actual rotation speed
2
. Voltage amp. circuit
●
The voltage amp. circuit amplifies the DC current level detected by the detection resistor after being
converted to a voltage and supplies it to the micro computer. Receiving this, the micro computer converts
it to a digital signal and compares it with the internal data to judge whether or not overload control is
required.
< During overload control >
●
The filter consisting of R2 and C515 removes high harmonic components from the voltage generated from
the DC current flowing to the detection resistor, and supplies it to OP1 pin
5
OP1 forms a non-inverting
voltage amp. circuit together with the peripheral elements.
●
The micro computer stores the set values which vary sccording to the rotation speed. When the DC current
level exceeds the set value, the micro computer enters the overload control state.
●
The set Value is determined by the amplification of the voltage amp. circuit.
●
Amplification : high
[
DC current : low
●
Amplification : low
[
DC current: high
{