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(2) Overload control circuit (OVL control circuit)
@
Overload control is to decrease the speed of the compressor and reduce the load when the load on
the air conditioner
increases to an overload state, in order to protect the compressor,
electronic
components and power breaker.
@
Overloads are judgement by comparing the DC current level and set value.
@
Fig. 8-4 shows the overload control system configuration and Fig. 8-5 is a characteristic diagram of
overload judgement values. There are two judgement methods-external judgement which compares the
externally set value with the DC current value regardless of the rotation speed and internal iudgement
which compares the set value that varies according to the rotation speed programmed in the micro computer
software with the DC current value.
© To power module
negative ©) terminal
DC
current
(R503)
Detection
resistor
Voltage amp.
'circuit
{Internal judgement)
_ DC voltage
AX-8J00 micro computer
Judgement OVL
with respect to
externally set
value
Motor contro!
process
Judgement OVL
according to the rotation
speed
AID
converter
A/D
converter
Rotation
speed
data
Selects data according
to the rotation speed and}
DC voltage.
OVL start current data
ne
i
ya
Se
ni nS
ee
es"
ee
ek
em, Sg
sd
dl
Fig. 8-4
Overload Control System Configuration
DC current
@® Overload external judgement circuit
Judgement value according to the rotation speed
(internal judgement value)
Rotation speed
Fig. 8-5
Bea)
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