A contactor is an electrical device used to control the flow of current in a circuit. Its working principle relies on electromagnetic induction. When the contactor coil is energized, it generates a magnetic field that attracts the movable iron core, which in turn causes the contactor's contacts to change state. Normally closed (NC) contacts open, while normally open (NO) contacts close, allowing the circuit to be completed. This mechanism enables the contactor to switch high-current circuits using a low-current control signal. When the coil is de-energized, the magnetic field disappears, and the spring-loaded armature returns to its original position, restoring the contacts to their default state. The NC contacts close again, and the NO contacts open. While AC contactors use alternating current for operation, DC contactors function similarly but are designed to handle direct current, often with additional features to prevent arcing and ensure stable performance. Understanding this principle is essential for anyone working with industrial automation or electrical systems.
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