Power Switchboard

a unit containing a set of interconnected electrical equipment and instruments mounted as a structural unit on a rack, switchboard, or panel with the purpose of receiving and distributing electric power at electric power stations and step-down substations and at industrial shops.

High-voltage power switchboards as a rule contain circuit breakers, a feeder breaker, metering assemblies, and sets of protective relays. The feeder breaker is mounted on a roll-out dolly to facilitate inspection and repairs. Low-voltage power switchboards contain link cutouts, knife switches, fuses, automatic circuit breakers, and sets of meters and protective apparatus. The operation of the unit is monitored by meters, protective devices, and signal lamps, all mounted on the front panel, along with the control levers and buttons. Power switchboards can switch circuits both under rated operating conditions and during short circuits. For safety during inspection and repair, a unit is equipped with an automatic block system that is triggered when the housing is opened or the cell is pulled out.