Hitachi RAI-50NH5 - Page 73

– 83 –
60
Fig. 8-6
Fig. 8-7
Voltage at microcomputer pin
Rotation speed of compressor
Deceleration DecelerationAcceleration Acceleration
Commanded rotation speed
Actual rotation speed
59
61
58
+
60
Is
D104
L
CT1
N
R005
0V0V
0V
0V
0V0V
R247
R006
C105
+
C217
C009
R222
C218
R221
R248IC4
+
–
6
5
7
Is
Id
Vd
CN13
CN14
R24
N1
DC 260-380V
SPM2
MAIN P.W.B.
P2
Direct Current
DC Current
Detection Resistor
HIC
IC1
Microcomputer
D205
D204
C224
0V
C222
0V0V
5V
5V
R253
R249
R500
+
C205
0V
5
1
373938
R245
10
1
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 microcomputer. Receiving this, the microcomputer 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 R245 and C217 removes high harmonic components from the voltage generated
from the DC current flowing to the detection resistor, and supplies it to IC4 pin 5 IC4 forms a non-inverting
voltage amp. circuit together with the peripheral elements.
● The microcomputer stores the set values which vary according to the rotation speed. When the DC current
level exceeds the set value, the microcomputer 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
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0274E Pg 57-88(RAI-50NH5) 19/10/05, 3:35 PM83