ACT 1500-2500, User Manual

Page: 23 / 68

Technical description
ACT 600 – 5000
23 – EN
7.13 Refrigerant pressure switches LPS – HPS
As operation safety and protection of the dryer a series of pressure switches are installed in the gas circuit.
LPS :
Low-pressure protection device on the suction side of the compressor, trips if the pressure drops
below the pre-set value. The values are automatically reset when the nominal conditions are
restored.
Calibrated pressure : R 407 C Stop 24.7 psig (1.7 barg) - Restart 53.7 psig (3.7 barg)
HPS :
This high-pressure controller device, located on the discharge side on the compressor, is activated
when the pressure exceeds the pre-set value. It features a manual-resetting button mounted on the
controller itself.
Calibrated pressure : R 407 C Stop 435 psig (30 barg) - Manual reset P<334 psi (P<23 bar)
7.14 Compressor crankcase heater
At low temperatures oil can more easily be mixed with the refrigerant gas. So, when the compressor starts,
oil can be drawn into the refrigeration circuit and liquid hammering could occur.
To prevent this, an electrical resistance heater is installed in the suction side of the compressor. When the
system is powered and the compressor is not running, this heater keeps the oil at the correct temperature.
This heater is controlled by a thermo switch which prevents overheating the oil.
NOTE : The heater must be powered at least a couple of hours before the start up of the refrigeration
compressor.