Electromagnetic starter, also known as an electromagnetic starter or magnetic starter, is an automatic switching device used to directly start and control AC motors (typically three-phase asynchronous motors).
It is the most common motor control device in industrial control, and its core consists of a **contactor** and a **thermal overload relay**.
Core Definition: An electromagnetic starter uses the magnetic field generated by an electromagnetic coil to attract contacts, thereby connecting or disconnecting the motor’s main power supply. It not only starts and stops the motor but also provides overload and undervoltage protection.
Main Functions and Features:
Remote/Automatic Control: Can be remotely operated via buttons, sensors, or a PLC (Programmable Logic Controller), eliminating the need for manual operation of high-current switches.
Overload Protection: When the motor load is too high, causing the current to exceed the set value, the thermal relay trips, cutting off the power supply and preventing the motor from burning out.
Undervoltage Protection: When the mains voltage suddenly disappears or becomes too low, the contactor coil automatically releases, cutting off the motor power supply. After voltage restoration, the motor will not automatically restart (the start button must be pressed manually again) to prevent accidents.
Frequency Operation: Designed for frequent circuit connection and disconnection, its lifespan is far longer than that of ordinary knife switches.
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