Salzer controls ltd supplies a changeover switch with unique design that are marketed by larsen & toubro and are available with all l&t; stokists. Changeover switches are useful for many applications, of which the most common application is eb-gen [electricity board mains to standby generator] changeover. The switch is either 3-pole or 4-pole and uses a common handle to changeover the supply from eb mains to generator when the power fails, and vice versa. The inside mechanism takes care that one source of power supply must switch off before switching on the other source. Thus an external interlock key does not required. This is an on-load changeover switch, and has three positions. The fourth pole is used for neutral and has advanced contacts, i.E. When the switch position is either in eb or gen, first the neutral contact of the source makes a contact, then the three poles make contact. The neutral contact remains closed for some time before it opens, when the main contact is open. The switch comes in 25 a, 32 a, 40 a and 63 a ratings in different mounting styles like front mounting, rear mounting with padlock and door interlock. These switches are also available in powder coated sheet steel enclosure.6- and 8-pole on-off switches can also be manufactured using the same mechanism.
