Hanbell RC2-D, Technical Manual

Page: 35 / 55

RC2-D Technical Manual
37
7.5.2 Liquid injection diagram
The NTC resistance signal of the built-in motor temperature of the compressor controls the motor
liquid injection solenoid valve according to the motor temperature. It is recommended to open at
80
℃
and close at 60
℃
7.6 Key points for compressor application
7.6.1 Pump-down
Do not pump-down the refrigerant in the compressor except for temporary maintenance or long
term shutdown. The pump-down will cause the refrigerant at the suction side to be insufficient,
which leads to abnormal high temperature in the compression chamber and the motor overheating.
When pump-down, please pay attention to the following items:
1) It is recommended to pump-down when the compressor is at 100% load.
2)
The pump-down should be completed at one time, because the repeated
pump-down is harmful to the compressor and compression chamber.
3)
When pump-down, the minimum suction pressure should be kept above 0.5bar
4)
When pump-down, the discharge temperature should be kept less than 100C.
5)
Pay attention to the high and low pressure of the compressor and the noise during
operation. If there is any abnormal situation, stop the pump-down immediately.
7.6.2 Long term partial load operation
If the compressor must be operated continuously under the condition of less than 50% load,
although the compressor is running in its limit curve or the motor temperature is lower than the
overload trip setting value, the motor heat dissipation will be insufficient due to the low suction. If
the compressor is running for a long time under high temperature, the motor will be deteriorated
gradually due to insufficient heat dissipation, and the motor will be seriously damaged. When
operating under this severe condition, it is recommended to open the liquid injection when the
motor coil temperature exceeds 80
℃
.