Relay is a kind of electronic control device, through which low-voltage controller can be used to control high-voltage electrical appliances. It has a control loop (output)The high voltage control system can be separated from the low voltage control system. Depending on the type of input signal,Relay can be divided into current relay, voltage relay, temperature relay, pressure relay and time relay. It can also be divided into electromagnetic relay, electronic relay, electrical relay, inductive relay, optical relay, thermal relay, etc