Relay is an automatic switching element with isolation function. It is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment. It is one of the most important control elements.
Relays generally have an induction mechanism (input part) that can reflect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); The actuator (output part) of "off" control; between the input part and the output part of the relay, there is also an intermediate mechanism (drive part) for coupling and isolating the input, functional processing and driving the output part.
As a control element, in summary, the relay has the following functions:
1) Expand the control range: For example, when the control signal of a multi-contact relay reaches a certain value, multiple circuits can be switched, disconnected, and connected at the same time according to different forms of contact groups.
2) Amplification: For example, sensitive relays, intermediate relays, etc., with a very small control quantity, can control a large power circuit.
3) Comprehensive signal: For example, when multiple control signals are input to a multi-winding relay in a prescribed form, they will be relatively integrated to achieve the predetermined control effect.
4) Automatic, remote control, and monitoring: For example, the relay on the automatic device and other electrical appliances can form a program control circuit to realize automatic operation.