Recent developments in electronic equipment have led to technically advanced appliances that require progressive electronic technologies. Today's equipment is required to perform multiple functions in limited size due its use of integrated circuit and microcomputer technology. Therefore, the components must be miniaturized and lightweight. As a result, functional limits of electromechanical relays have narrowed due to increasing contact amperage in smaller packages.
Relays are electrically controlled devices that open or close electrical contacts to affect the operation of other devices in the same or different circuits. A relay's most basic components are its coil, armature, and contacts. When the relay is put into a given circuit, the current from that circuit induces a magnetic field in the relay coil. The magnetic field then affects the armature in such a fashion that it causes the contacts to make or break the part of the circuit that is attached to the relay output.