In refrigeration system the High Pressure (HP) cut-off switch is a control device which is used as safety control. The compressor is stopped by cutting the power supply of the motor of the compressor whenever the discharge pressure of the compressor becomes excessive. This is necessary to prevent the possible damage of equipment.
The HP switch monitors the system for an inoperative outdoor motor, and/or a dirty/restricted condenser (outdoor) coil.
When the pressure in the system exceeds the HP switch setting, the switch will open circuit the compressor clutch and the compressor will stop circulating refrigerant. The high pressure setting of the switch must correspond to the type of refrigerant in the system. Different refrigerants require different settings.