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Detection
Vd
R5
Micro
computer
HIC
Fig. 8-6
eS
—e
Voltage at micro computer
pin @
Rotation speed of compressor
Commanded rotation speed
Actual rotation speed
Deceleration
Acceleration
Acceleration
Fig. 8-7
(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 © 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
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