7-2. Outline of Main Controls
1.
Pulse Modulating Valve (PMV) control
1) For PMV with 40 to 500 pulses during operation, respectively.
2) In cooling operation, PMV is controlled with the temperature difference between TS sensor and TC sensor.
3) For the temperature difference in item 2), 1 to 5K is aimed as the target in both cooling operation.
4) When the cycle excessively rose in both cooling operations, PMV is controlled by TD sensor.
The aimed value is usually 90°C in cooling operation.
REQUIREMENT
A sensor trouble may cause a liquid back-flow or abnormal overheat resulting in excessive shortening of the
compressor life. In a case of trouble on the compressor, be sure to check there is no error in the resistance value
an the refrigerating cycle of each sensor after repair and then start the operation.
2. Discharge temperature release control
1) When the discharge temperature did not fall or the discharge temperature rapidly went up by PMV control,
this control lowers the operation frequency. It subdivides the frequency control up to 0.6Hz to stabilize the
cycle.
2) When the discharge temperature detected an abnormal stop zone, the compressor stops and then restarts
after 2 minutes 30 seconds.
The error counting is cleared when the operation continued for 10 minutes. If the error is detected by 4
times without clearing, the error is determined and restarting is not performed.
*
The cause is considered as excessively little amount of refrigerant, PMV error or clogging of the cycle.
3) For displayed contents of error, confirm on the check code list.
Frequency normal down
Frequency slow down
Frequency hold
Frequency slow up
(Up to command)
As command is
Abnormal stop
TD [ºC]
a
b
c
d
e
a
111
b
109
c
106
d
103
e
96
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