Relays are electromagnetic switches used to control the flow of electric current in a circuit. They consist of a coil and one or more sets of contacts. In circuit diagrams, relay symbols are used to represent these devices.
In operation, when a voltage is applied across the coil terminals, it generates a magnetic field that causes the movable contacts to change their position, either opening or closing the circuit on the other side of the relay. This makes relays useful for controlling high-power or high-voltage circuits with a low-power control signal.
The specific configuration and behavior of the contacts (normally open, normally closed, or both) depend on the type of relay. Relay symbols may also include additional markings to indicate the nature of the contacts, such as normally open (NO), normally closed (NC), or changeover (CO).
These symbols provide a standardized way to represent relays and their coils in circuit diagrams, making it easier for engineers, electricians, and technicians to understand and design complex electrical systems.
