Electromagnetic relay is an electronic control device. It has a control system (also called input loop) and a controlled system (also called output loop). It is usually used in automatic control circuits. It actually uses a smaller current.
Application of electromagnetic relay
Anti-alarm alarm: K is a contact switch, B is a funnel-shaped bamboo cylinder, and there is a float A. When the water level rises above the warning line, the float A rises, so that the control circuit is connected, and the electromagnet draws the armature. Therefore, the indicator lamp circuit of the alarm is turned on, and the lamp lights and alarms.
Automatic temperature alarm: when the temperature rises to a certain value, the mercury surface of the mercury thermometer rises to the metal wire, and mercury is a conductor. Therefore, the electromagnet circuit is connected, the electromagnet attracts the spring piece, and the bell circuit is closed, and the bell rings an alarm. When the temperature drops, the mercury surface leaves the wire, the electromagnet circuit is disconnected, the spring piece returns to its original state, and the bell circuit is disconnected. The bell no longer sounds.
Electromagnetic relays are important components in electric bells, telephones and automatic control circuit devices. Their essence is switches controlled by electromagnets, which play a similar role to switches in circuits:
Use low voltage and weak current to control high voltage and strong current;
Realize remote control and automatic control.
The use of electromagnetic relays can use low voltage and weak current control circuits to control high voltage and high current working circuits, and can realize remote control and production automation. Electromagnetic relays are widely used in automatic control (such as refrigerators, automobiles, elevators, machine tools Control circuit) and communication field.