What is a relay primarily used for in electrical systems?

A relay is primarily used as a switching device in electrical systems. It functions by using an electromagnetic coil to mechanically operate a switch that can turn circuits on or off without direct manual intervention. This capability is crucial in various applications, including automation systems, remote control systems, and protection devices.

The design of a relay allows it to control a higher powered circuit using a lower power signal, making it versatile in situations where isolation between high and low voltage circuits is necessary. For example, when a low voltage signal energizes the relay's coil, it closes or opens the switch contacts, thereby controlling the flow of electricity in the larger circuit. This characteristic enables the relay to serve functions such as turning on large motors, lights, or other equipment based on a smaller signal.

Understanding the operation of relays is essential for electricians as they form a foundational aspect of control systems, allowing for effective management of electrical loads.