There are many commonly used relays, such as center relays, time relays, current relays, voltage relays, speed relays, thermal relays, solid-state relays, spring closing relays, and so on.

We need to select different relays based on our needs. For example, if you need to control the time, use a time relay; if you need to control the circuit on or off based on the voltage, use a voltage relay; if you need to control the circuit on or off through a magnetic field, use a reed relay, and so on.

Central relay

Central relay和沟通接触器原理类似，仅仅它比沟通接触器少了主触头，所以这就决定了它不能通断大电流。中心继电器首要效果：它能够添加触点的数量和传递信号。

Central relay实物图，如下

Current relay

Current relay，望文生义就是依据电流信号来到达操控线路通断。它有过电流继电器和欠电流继电器，也有同时具有过电流和欠电流功用。比方为了维护某个设备设备因电流过大而焚毁，就能够选用电流继电器。

Solid state relay

Solid state relay望文生义就是这个继电器是一块整体，中心没有触点。它首要是由电子电路组成，输入电路与输出电路之间选用光电阻隔。别的由于它无触点，所以能够实现频频接通与断开而且不会发生电弧，能够适用于易燃易爆场所。

Thermal relay

Thermal relay，望文生义就是依靠电流发生热量来到达接通与断开操控线路的意图。热继电器主触头是由两种不同材料的金属片组成，当电流经过双金属片会发生热量。双金属片受热膨胀曲折，然后推动连杆，然后让辅佐触头接通与断开。

Article source: Zhongshan Relay Manufacturer www.jxzhongxuan.com