Hager Centre off changeover switch, on - off - on, 4-pole, 40A

A changeover contact is part of a relay, on which the normally open contact can break or make contact. A relay can contain several changeover contacts. They are designed to transfer a house (or business) electricity from the commercial power grid to a local generator when n outage occurs. Also known as “transfer switches,” they connect directly to the generator, commercial power supply or line, and the house. The main difference between a relay and a switch is that a switch is operated mechanically while a relay is operated electrically.