继电器广泛用于生产控制的电力系统中，其作用是利用它的常闭



和常开触点进行电路切换。由于继电器是利用改变金属触点位置，使



动触点和定触点闭合或分开，所以具有接触电阻小，流过电流大和耐



压高等优点，特别适用于大电流高电压的使用场合。小型继电器也常



用作精密测量电路的转换开关。-Relays are widely used in electricity production control system, its role is to make use of its normally closed and normally open contacts for circuit switching. Relay is to use change as a result of metal contact, and make the moving contact and fixed contact closure or separate, so with a small contact resistance, current flow and the pressure high, especially for high-voltage high-current use of occasions. Small relays are used in precision measurement of the change-over switch circuit.