According to the CEI 17-3 standard, a contactor or remote switch is a mechanical manoeuvring device, generally designed to perform a high number of operations. It is also known as a monostable device because it has a single idle position, not activated manually, and able to establish, withstand and cut off current in overload conditions.
The idle position usually corresponds to the open position of the main contacts. It is different from a relay switch due to the fact that this latter is used to control relatively low power or signals in an electronic environment, while a remote switch is also used to control much higher power levels.