It is a hydraulic-to-electrical signal conversion component that emits an electrical signal when the oil pressure reaches a predetermined value. When the pressure of other oil ports reaches the set value of the spring, the circuit can be automatically connected or disconnected, so that electrical components such as electromagnets, relays, and motors are energized to operate or stopped when powered off, so as to control the working procedures of the hydraulic system. Safety protection or action linkage, etc.
The role of pressure relay in the refrigeration system: In industrial refrigeration, the pressure relay is an electrical switch controlled by a pressure signal. It is often used to directly control the start and stop of the refrigeration compressor. Protection and adjustment components or control the opening and closing of some solenoid valves.
Pressure relays used in refrigeration devices are divided into two categories: low-voltage relays and high-voltage relays according to their pressure control range. There are also two types of relays that are assembled into one housing and share one electrical contact to form a combined high and low voltage relay.
The refrigeration compressor is often equipped with a low-voltage relay that directly controls the starting circuit. It uses the compressor suction pressure as the action signal. Its function is: when the suction pressure is too low , the compressor automatically stops to prevent air from leaking into the system from the pipeline or shaft seal, and plays a low-pressure protection role.
In small refrigeration devices, in addition to low-pressure protection, the compressor can also start and stop automatically according to the set suction pressure to keep the cold storage temperature stable. regulating effect. In large and medium-sized devices, due to the large starting current of the compressor, low-voltage relays are often not used to automatically start the compressor, so it only plays a role in low-voltage protection.
In addition, some piston compressors are also equipped with low-pressure relays. These pressure relays are the central part of the equipment, the heart of controlling the normal operation of the equipment, and the appearance of the equipment. The problem is the scavenger, so when choosing good equipment, you must first see whether its pressure relay can withstand the damage of the equipment. If its endurance is enough to bear the load of the equipment, it is a good pressure relay.
Adjustment method of pressure relay
(1) Low pressure adjustment, adjust the low pressure adjustment screw T according to the pressure value corresponding to the required evaporation temperature: When a higher evaporation temperature is required, a screwdriver can be used to rotate counterclockwise Low pressure adjustment screw T;if a lower evaporation temperature is required, the adjustment screw T can be rotated clockwise.
(2) Adjustment of high pressure. In order to ensure the safety of the operation of refrigeration equipment, pressure relays are mostly used in water-cooled condenser refrigeration machines. Their main function is to prevent cooling water Interruption or insufficient cooling water flow causes a sudden and rapid increase in condensation pressure, leading to serious accidents. The high pressure value is generally set at 1Q~11kg/cm, z, r-turn, 31 (using Freon 12 refrigerant). When adjusting, use a screwdriver to turn the high-pressure adjustment screw M clockwise to increase the pressure value, and turn it counterclockwise to decrease the pressure value.
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