Principle of action: low-pressure gas acts on the low-pressure bellows. When the low-pressure pressure is higher than the upper limit of the given value, the drive mandrel and drive rod overcome the pressure of the low-pressure adjusting spring and press the button of the micro switch. At this time, the circuit If the low pressure of the walk-in cooler is lower than the lower limit of the given value, the elastic force of the low-pressure adjusting spring overcomes the pressure from the bellows and lifts the transmission rod to make the micro switch open and the circuit is disconnected. The compressor stops. The high pressure and low pressure cut-off pressure values ​​can be adjusted through the high pressure differential or low pressure differential adjustment dial. If the pressure of the adjusting spring is increased, the opening pressure value will increase accordingly; otherwise, it will decrease. The differential pressure value of high or low pressure (referring to the pressure difference between on and off) can be adjusted by the high or low pressure difference adjustment dial. When the pressure difference adjustment dial is rotated to increase the pressure of the disc spring, the differential pressure The pressure value increases accordingly. During installation, the low-pressure pipe and the high-pressure pipe of the high and low pressure combination controller are respectively connected with the suction pipe and the discharge pipe of the compressor, and the suction and discharge pressure of the walk-in cooler compressor are sensed respectively to generate corresponding control actions. The high and low pressure combined controller has a low pressure control range of 0.05 to 0.6 MPa, and a high pressure control range of 0.6 to 2.0 MPa, which can be applied to ammonia and freon systems.

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