What Is A Relay

Relay, also known as electrical relay, is an electronic control device. It has a control system (also known as an input loop) and a controlled system (also known as an output loop). It is usually used in automatic control circuits. It is actually A kind of "automatic switch" that uses a smaller current to control a larger current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit. The relay coil is represented by a rectangular box symbol in the circuit. If the relay has two coils, draw two parallel rectangular boxes. At the same time, mark the text symbol "J" of the relay in or beside the long box. There are two ways to represent the contacts of the relay: one is to draw them directly on the side of the long box, which is more intuitive.