What is a Electromagnetic switch?

An electromagnetic switch is a switch that combines an electromagnetic contactor that opens and closes an electric circuit with the action of an electromagnet and a thermal relay that breaks the circuit when overloaded. They are also called magnetic switches, and are used as switches for motor operation and remote control. Magnetic contactors often have three main contacts for three-phase power. In addition, there are some auxiliary contacts, which have a lower current rating than the main contacts. It is used for energizing lamps and buzzers that notify open/close status and overload, and for self-holding circuits. A thermal relay detects overcurrent that flows when overloaded and outputs a signal, and does not itself have a function to cut off the circuit. Therefore, it is used in combination with an electromagnetic contactor that has a circuit breaking function.

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