The entire refrigeration system needs
which may be an expansion valve or a capillary tube.
In circuits equipped with a capillary tube, the pressures on the suction and discharge sides are equalized during the compressor shutdown. In this type of circuit, the compressor is equipped with a low starting torque motor.
Already in a circuit with expansion valve, there is only
refrigerant through the valve while the compressor is on. Therefore, the pressures between suction and discharge do not equalize. In this case, the compressor is equipped with a high starting torque motor.
The appropriate compressor motors for these two systems are called:
LST. Low Starting Torque Low starting torque, employee
in capillary tube systems.
HST. Hight Starting Torque High Starting Torque, Employee
in systems with expansion valve.
Note:
HST compressors can be applied to systems using LST (capillary tube) compressors when the shutdown periods are too short, not allowing pressure equalization.
However, LST compressors can not be applied to systems with expansion valves.
