What is the pressure relay used for?
A relay is a control device commonly used in our lives. In a popular sense, it is a switch, which is turned off or turned on when conditions are met. The switching characteristics of relays are widely used in many control systems, especially discrete control systems.
The pressure relay looks very novel. It is easy to understand that it is connected with the electric contact pressure gauge. In fact, they are similar. Compared with commonly used relays, only the driving force for the contact action is different. The relay uses coils to energize the contacts, and the pressure relay uses pressure to make the contacts work.
Basic information of pressure relay
Pressure relays have diaphragm type, plunger type, spring tube and bellows type. Although the four structures of the pressure relay are different, they all use the pressure of the fluid medium to turn on or off their contacts. Therefore, when it is used in the hydraulic system, the pressure value should be set according to the process, but when the pressure of the hydraulic system reaches the set value, a signal is sent to make the electrical components, actuators, motors, etc. act.
The role of pressure relay
The function of the pressure relay is that when the pressure of the hydraulic system rises to a certain value, it sends out an electrical signal and manipulates electrical components (such as solenoid valve coils or intermediate relays, etc.) to achieve sequential actions or play a role in safety protection.
The role of pressure relay in refrigeration system
In industrial refrigeration, a pressure relay is an electrical switch that is controlled by a pressure signal. It is often used as a protection and adjustment element that directly controls the start and stop of a refrigeration compressor or controls the opening and closing of certain solenoid valves. Pressure relays used in refrigeration equipment are divided into two types, low-voltage relays and high-voltage relays according to their pressure control range. There are also two types of relays assembled in a housing and sharing 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, and its function is:
(1) When the suction pressure is too low, the compressor is automatically stopped to prevent air from leaking into the system from the pipeline or shaft seal, and plays a low-pressure protection role.
(2) In a small refrigeration device, in addition to low-pressure protection, the compressor can be automatically started and stopped according to the set suction pressure to keep the temperature of the cold storage stable and play the role of storage temperature regulation. In large and medium-sized devices, since the starting current of the compressor is large, low-voltage relays are not often used to automatically start the compressor, so it only plays the role of low-voltage protection.
(3) 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 the normal operation of the equipment, and the scavenger when the equipment has problems, so choose it The equipment must first see whether his pressure relay can withstand the destruction of the equipment. If it can bear the load of the equipment, it is a good pressure relay. Therefore, when choosing a pressure relay, you must buy a regular brand product.