How Relays Work - Basic working principle electronics engineering electrician amp

Summary

An educational guide explaining the working principles, types, and practical applications of electrical relays, including electromechanical and solid-state designs.

Highlights

What is a Relay?00:00:55

A relay is an electrically operated switch used to control a circuit with a low-power signal or to isolate circuits. It allows low-amperage switches or sensors to control high-capacity loads.

Core Components and Operation00:01:49

Relays consist of a primary control circuit (often low voltage DC) and a secondary load circuit. The primary side uses an electromagnetic coil to attract an armature, which moves a contactor to open or close the secondary circuit.

Solid State Relays (SSRs)00:04:56

Unlike mechanical relays, SSRs have no moving parts. They use optical coupling via an LED and a photosensitive transistor to isolate and switch circuits, utilizing semiconductor properties.

Types of Relays and Switching00:07:13

Explanation of normally open and normally closed relays, along with specialized types like latching relays which maintain position through memory, and double-pole/double-throw relays for complex circuit control.

Protection Against Back EMF00:12:38

When an electromagnet loses power, the collapsing magnetic field generates a voltage spike known as back EMF. A diode is used to provide a safe discharge path for this energy, preventing circuit damage.