Relays is an electrical control device, which is an electrical device that causes a predetermined step change in the controlled quantity in the electrical output circuit when the change in the input quantity (excitation quantity) reaches the specified requirements. It has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop).
As a control element, in summary, the relay has the following functions: 1) Expanding the control range: For example, when the control signal of the multi-contact relay reaches a certain value, the multi-circuit can be switched, disconnected and connected at the same time according to different forms of the contact group.
2) Amplification: For example, sensitive relays, intermediate relays, etc., can control very large power circuits with a very small amount of control.
3) Comprehensive signal: For example, when multiple control signals are input to the multi-winding relay in a prescribed form, after a comprehensive synthesis, a predetermined control effect is achieved.
4) Automatic, remote control, and monitoring: For example, the relays on the automatic device together with other electrical appliances can form a program control circuit to achieve automatic operation.
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.