A relay is an electromechanical switch that is operated by an electrical current. It consists of a coil of wire (electromagnet) that, when energized, generates a magnetic field that causes a movable armature or contact to move, either making or breaking electrical connections.
Here's how a relay typically works:
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Coil: A relay contains a coil of wire that is wound around an iron core. When an electrical current flows through this coil, it generates a magnetic field around the core.
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Armature: The magnetic field produced by the coil attracts or repels a movable component called the armature. The armature is typically a ferromagnetic material (such as iron) that is attracted to the magnetic field when the coil is energized.
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Contacts: The armature is connected to one or more electrical contacts. When the armature moves due to the magnetic field, it either makes or breaks electrical connections between these contacts.
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Switching Function: Relays are used to control the flow of electrical power in a circuit. When the relay coil is energized, it closes (makes) the contacts, allowing current to flow through the circuit. When the coil is de-energized, the contacts open (break), interrupting the current flow.
Relays are commonly used in various applications for switching high-power or high-voltage circuits using low-power control signals. They provide isolation between the control circuit (coil side) and the controlled circuit (contact side), allowing different voltage levels or incompatible systems to be interfaced safely. Relays also offer advantages such as electrical noise immunity, long-term reliability, and the ability to handle transient overloads.
There are various types of relays, including electromagnetic relays, solid-state relays (SSRs), reed relays, and others, each suited for specific applications based on factors such as switching speed, current and voltage ratings, environmental conditions, and longevity requirements.
