The pressure switch of the refrigeration system is a safety device used to monitor and control the pressure of the refrigerant in the refrigeration system. It is usually installed on the high or low pressure side of the refrigeration system to detect pressure changes in the system and automatically open or close the circuit according to the preset pressure value, thereby controlling the operation of the compressor or other related equipment.
The main functions of a pressure switch include
Protection system: When the system pressure is too high or too low, the pressure switch can cut off the power and stop the compressor from working to prevent system damage or failure.
Control and regulation: Some advanced pressure switches can also be used to regulate the working status of the system, such as maintaining pressure stability within the system by controlling components such as expansion valves.
Safety alarm: When abnormal pressure is detected, some pressure switches can also issue alarm signals to remind operators to take measures.
There is usually an adjustable spring mechanism inside the pressure switch. When the pressure reaches the set point, the spring will cause the contacts to close or open, thus completing the circuit connection or disconnection. This mechanical pressure sensing method is simple and reliable, and has been widely used in various refrigeration and air conditioning systems.
While ensuring the normal operation of the refrigeration system, the pressure switch also plays an important role in safety protection. Proper selection, installation, and maintenance of pressure switches are crucial for ensuring the safety and efficiency of the entire refrigeration system.
Internal structure of pressure switch: The pressure switch contains a single pole double throw proximity switch, which allows setting two switching points: upper limit switching value and lower limit switching value.
Debugging method
Upper limit switching value adjustment: By rotating the adjustment screw on the top right side, the upper limit switching value can be set.
Adjustment of pressure difference (i.e. the difference between upper and lower limits): This difference can be adjusted by rotating the adjustment screw on the top left side. The relationship between the two is: upper limit switching value - switch pressure difference=lower limit switching value.
Example:
If it is necessary to maintain the controlled pressure between 0.5 and 0.8 MPa:
Select a pressure controller with a setting range of 0.1 to 1.0 MPa.
Adjust the right adjustment screw to point the pointer at 0.8MPa, and determine the upper limit switching value.
The left adjustment screw is set to a pressure difference of 0.3MPa, so the calculated lower limit switching value is 0.5MPa (0.8MPa -0.3MPa=0.5MPa).
Electrical connection instructions
High voltage protection: Under normal circumstances, the common terminal ① is connected to the normally closed terminal ⑤. When the upper limit is reached, it is disconnected and instead connects the common terminal ① to the normally open terminal ③. When the pressure drops back to the set lower limit, restore the original state.
Low voltage protection: If it is desired to cut off the power supply below 0.1 MPa, an upper limit of 0.15 MPa and a lower limit of 0.1 MPa should be set. When the pressure drops to 0.1MPa, the equipment will automatically shut down to provide protection.
Precautions for use
Ensure that the upper limit setting value is greater than the pressure difference setting value, for example, if the upper limit is set to 8 kilograms and the pressure difference is set to 2 kilograms, the actual operation will start at 6 kilograms and stop at 8 kilograms.
After completing the setting, please ensure that the action point of the pressure switch matches the actual pressure gauge reading. If there is any deviation, it should be adjusted promptly until it is accurate.
