How To Switch Bedrooms

What Does a Relay Switch Do?

CC BY-SA 3.0/Balurbala/Wikimedia Commons

A relay switch, or simply a relay, is a small electromechanical device that controls a pair of movable contacts or circuit parts, moving from an open to a closed position and vice versa. The primary purpose of a relay switch is to either make or break a contact without human intervention via a signal that switches the contact on or off. Relays take only a small amount of power from an electromagnet to do this. However, the ability to control the movable contacts makes relays an ideal switch for motors, heaters, lamps and AC circuits — all of which have high-powered circuitry.

Relay Design

A typical relay switch has a few standard features, including an electromagnet, a movable armature, a yoke and a frame/stand/spring. The most important part of a relay switch is the electromagnet, which powers the small device. The electromagnet triggers the movable armature to either connect or break the contact in the relay switch, which in turn connects to the terminals. If power is coursing through the coil around the electromagnet, the yoke attracts and holds the armature in place. The spring is an optional part of the design and serves to make the armature move more easily.

How Relay Switches Work

When no current is running through the coils around the core, it won't be able to generate a magnetic field and won't be able to attract the movable armature. Therefore, the movable armature normally stays in closed position or NC. Once it becomes an electromagnet as voltage is applied to the core, the electromagnet attracts the movable armature and pulls it to a normally opened pin, thus completing the circuitry. De-energizing the core moves the armature back to its NC position.

Types of Relay Switches

The relay switch in the earlier section described how basic electromechanical relays work. However, there are also other types of relay switches that work on similar principles. One of these types is the electrothermal relay that uses heat to bend a metallic strip to open the connections. Solid state relay, on the other hand, uses a semiconductor device instead of mechanical parts. Hybrid relays, polarized relays and non-polarized relays are among the other types of relays.

Applications of Relay Switches

There are a host of applications for relay switches, but its main function is to manage and control high voltage circuitry, or AC, with the low voltage power supply, or DC. Although relays are popular in large electrical circuits, they are also in computer circuits to enable them to operate and process algorithms.

Relay switches are also important in automatic stabilizers to help them determine whether the supply voltage is different from what its rated. Once it senses voltage variations, it controls the load circuit along with circuit breakers. Other applications of relay switches include circuit selections within one system, television set circuitry, traffic signal controllers and thermal controllers.

How To Switch Bedrooms