Functions and classifications of relay

   Relay is a kind of electrical control device, which is used to convert a certain electric quantity or non-electric quantity into a switch quantity to realize the automatic control function of the circuit. It is widely used in automatic control, mechatronics and power electronic equipment；

Relays are classified in various ways, including voltage relay, current relay, time relay, speed relay, pressure relay and so on. According to the working principle, there are electromagnetic, inductive, electric and electronic types. According to the purpose, there are control relays and protection relays.