A relay symbol is an image used to denote an electrically operated switch in a schematic diagram. A schematic diagram is a representation of the elements of an electrical system.
The most basic type of relay symbol is a rectangle with a diagonal line passing through along with two short vertical lines -- one coming from the top-center of the rectangle and one coming from the bottom-center of the rectangle. A relay symbol, however, can come in many different forms, depending on the type of relay. It is generally accompanied by a switch symbol.
Other types of relay symbols include the relay/solenoid operated coil and switch, the electronic relay, the double coil relay, the overcurrent relay, the fast deactivation relay, the differential current relay, the relay slow excitation, the slow deactivation relay, the high speed relay, the maximum voltage relay, the relay fast, the defective relay actuated voltage, the card operated relay, the relay not affected by AC, the differential relay, the polarized relay, the magnetically polarized relay, the delayed action relay to disconnect, the electromagnetic relay, the thermal relay, the AC relay, the step relay or mechanical interlock relay, the remanence relay, the relay rest with delayed operation, the relay remnant, the electrovalve, the intermittent relay, the pulse relay, the relay mechanical resonance and the reed relay.