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7-2. Outline of Main Controls
1. PMV (Pulse Motor Valve) control
1) The aperture of the PMV (1, 2) is controlled between 88 (44 + 44) to 1000 (500 + 500) pulses during
operation.
2) During cooling and heating operations, the PMV aperture is controlled by the temperature difference
between a detected temperature from a TS sensor and a saturation temperature equivalent value
(TU temperature) from a Ps sensor. (SH control).
3) The temperature difference in 2) in both cooling and heating operations is usually controlled using a 5K
target value.
(However control may be performed within a range of 1 – 15K depending on operating conditions).
4) When the cycle overheats during both cooling and heating operations, the PMV aperture is controlled
using a detection value from a TD sensor.
The normal target value is 96°C for cooling operations and 102°C for heating operations.
CAUTION
Sensor malfunction may cause liquid back-flow or error overheating in the compressor resulting in dramatic
reduction in the durable life of the compressor.
In the event of malfunction and repair of the compressor, restart operation after checking that there are no
errors in the resistance values or the refrigerating cycle of each sensor.
2. Discharge temperature release control
1) This control lowers the revolution number of the
compressor in the event that the discharge
temperature is not reduced or in the event the
discharge temperature increases rapidly during
PMV control.
The cycle is stabilized by dividing compressor
revolution number control into units up to 0.6 rps.
2) When the detected discharge temperature is in
an error zone, compressor operation is stopped
and then restarted after 2 minutes 30 seconds.
An error count is added on each occasion the
error zone is detected and when the error is
detected 4 times, a “P03” error is performed.
When normal operation continues for a period of
10 minutes, the error count is cleared.
115
113
95
102
105
TD (˚C)
Abnormal stop
([P03] is displayed with count 4 of errors)
Frequency slow down
According to command
Frequency slow up (Until command)
Frequency hold
Frequency normal down