Relay is an automatic switch element with isolation function. When the change of excitation volume reaches the specified value in the input circuit, the automatic circuit control device that can control the electric quantity in the output loop will have a step change. It has an induction mechanism that can respond to some external excitation quantity (electricity or non electricity), an actuating mechanism that controls and controls the controlled circuit, and an intermediate comparison mechanism that can compare, judge and transform the size of the excitation volume. Relay is widely used in remote control, telemetry, communication, automatic control, mechatronics and aerospace technology. It plays the role of controlling, protecting, regulating and transmitting information.
The relay generally reflects the input variables (such as current, voltage, power, frequency, impedance, temperature, pressure, speed and light) of the induction mechanism (input); to the controlled circuit on and off control actuator (output) between the input part; and the output part of the relay, and are coupled to the input isolation function, treatment and mechanism of the middle part of the output (driver).
As a control element, the relay has several functions as follows:
(1) expand the control range: for example, when the control point of a multi contact relay reaches a certain value, it can be changed according to different forms of contact groups, and at the same time, switching, breaking and connecting multiple circuits.
(2) magnification: for example, sensitive relays, intermediate relays, and so on, with a very small control amount that can control a large power circuit.
(3) integrated signal: for example, when multiple control signals enter the multi winding relay according to the prescribed form, it will achieve a predetermined control effect after comparison.
(4) automatic, remote control and monitoring: for example, the relay on the automatic device can be programmed together with other electrical appliances to realize automatic operation.