Siemens GMI Series Instruction

Also see for 15-GMI-1000: Installation operation & maintenance

Interrupter/Operator DescriptionPage9condenseson thesurroundingvaporshield.Contactmaterialsandconfigurationareoptimized toachievearcmotionandtominimizeswitchingdisturbances.Primary DisconnectsFigure13isasideviewofthecircuitbreakerwithasidephasebarrier removedtoshowdetailsofthe primarydis-connects.Each circuit breakerhas threeupperandthreelowerprimarydisconnects.Upperprimary disconnectsareconnectedtothestationarycontactsofthevacuuminterrup-ters,and thelowerprimarydisconnects tothemovablecontacts.Each disconnect arm hasa setofmultiplespringloadedfingersthatmatewithbusbarsinthe Metal-Cladswitchgear.Thenumberoffingersinthedisconnectas-sembly varies with thecontinuousand/ormomentary ratingofthe circuit breaker.PhaseBarriersPhasebarriers arevariableamong GMIbreakersofdissim-liarvoltageandcontinuouscurrentratings.Figure14isarearviewofacircuit breaker thatshowsthetwoouter(phasetoground)insulatingbarriers.Somecircuitbreakerratingsalsohaveinner barriers(phasetophase).Thesefourplatesofglass polyesterinsulatingmaterialareattachedtothe circuitbreakerhousing andprovidesuitableelectricalinsulationbetween thevacuum interrupterprimarycircuits and thehousing.Figure14.BreakerwithInsulatingOuterPhase Barriers.Stored Energy OperatingMechanismThe storedenergy operating mechanismoftheGMIcircuitbreaker is an integratedarrangementofsprings,solenoids,andmechanical devicesdesignedtoprovide a numberofcritical functions.Theenergy necessarytoclose and openthecontactsofthe vacuuminterruptersisstored in powerfultripping andclosingsprings.These springs are normallychargedautomatically,but there are provisions for manualcharging.Theoperating mechanism that controlscharging,closing and tripping functionsis fully trip-free,i.e., springcharging doesnotautomaticallychange the position of theFigure13.Upper and Lower Primary Disconnects.Thereare three insulatingpushrods.Eachpush rod con-nects the movable contactofoneofthe vacuuminterruptersto the jack shaft driven by the closing andtrippingmechanism.Flexibleconnectorsensure secureelectricalconnections between themovable contactsofeach inter-rupter and its bottom primary disconnect.