15
3.14 Caution on pump down operation
At the pump-down operation, the rotation speed of compressor shall be lower than 60rps.
The operation time shall not exceed a limit of 10minutes.
3.15 Protection Devices Required
For air-conditioning or heat pump unit, the following protective devices should be installed:
1) Reverse Phase Protector
Scroll compressor will only compress in one rotational direction. This is very important for three phase
compressors since three-phase induction motor will run in either rotational direction equally depending on
phasing of the power. Reverse rotation will result in excessive noise, and no suction / discharge pressure
differential appears as well as no cooling effect in the suction line.
For three phase systems, mechanic device or reverse rotation module in the system control unit is necessary
in preventing three phases compressor from running in the reverse rotational direction.
2) Discharge Gas Thermostat
The discharge temperature will rise rapidly if the compressor is running under the overload conditions or lack
of refrigerant conditions
.
The maximum discharge temperature should be maintained by a discharge thermostat.
For C-SW series, a copper well pipe is installed on the end cap of compressor, which is filled with heat
conducting silicon to improve the heat transfer effect. The discharge thermostat shall be inserted into this well
pipe and the tripping point must not exceed 115
℃
.
Figure 3-5 Discharge Thermostat Installation
3) Low Pressure Switch
Panasonic scroll compressors require a low-pressure switch to protect against loss of refrigerant conditions.
The recommended settings are listed in Table 3-2.
