Emax Low voltage air circuit-breakers - ABB Download Center

Interlock between circuit-breakersThe mechanical interlocks possible are shown below, dependingon whether 2 or 3 circuit-breakers (any model and in anyversion) are used in the switching system.Type of interlock Typical circuit Possible interlocksType ABetween two circuit-breakersOne normal power supply and one emergencypower supplyGCircuit-breaker 1 canonly be closed if 2 isopen, and vice-versa.1 2O O1 2IOOIO = Circuit-breaker openI = Circuit-breaker closedType BBetween three circuit-breakersTwo normal power supplies and one emergencypower supply.G1 2 3Circuit-breakers 1 and3 can only be closed if2 is open.Circuit-breaker 2 canonly be closed if 1 and3 are open.1 2 3O O OI O OO O II O IO = Circuit-breaker openO I OI = Circuit-breaker closed5Type CBetween three circuit-breakersThe two half-busbars can be powered by asingle transformer (bus-tie closed) or byboth at the same time (bus-tie open)1 2 3One or two circuitbreakersout of threecan be closed at thesame time.1 2 3O O OI O OO I OO O IO = Circuit-breaker openI = Circuit-breaker closedO I II I OI O IType DBetween three circuit-breakersThree power supplies (generators or transformers)on the same busbar, so parallel operation isnot allowedGOnly one of threecircuit-breakers can beclosed.1 2 3O O OI O O1 2 3O I OO O IO = Circuit-breaker openI = Circuit-breaker closed5/20ABB SACE