Relay

A relay is an electronically operated switch that is remotely activated by an electromagnet which pulls a set of contacts to either make or break a circuit. Electrical relays are commonly used for switching signals, radio frequencies, high current circuits when using a lower current circuit, and loads such as resistive, motor, lamp, inductive, and capacitive applications. This is helpful when an in-line switch or existing circuit does not have the capacity to handle the required current.

Relays have the same subsystems and principles of operation regardless of whether these are electromechanical relays or electronic relays or designed to switch signal or high-power loads. Relays convert an electrical input signal on the primary side to an intermediate and non-electric physical signal. These devices also reconvert the non-electric physical signal to operate a switching element (secondary side) such as contacts which switch and conduct electrical current (i.e., output, load current). Relays use the non-electric signal between the primary and secondary side to provide the necessary galvanic separation between the input and output circuits. Relays enable a single output that can activate multiple circuits and functions, which helps increase cost savings because high current capacity switches cost more than lower current versions. Relays can also perform logic functions on certain inputs, such as latching an output on and off from a momentary input. When a switch cannot take a high current or is operated by electronic circuit, the relay can be operated by switch circuits.