Eaton Magnum DS Technical Data Manual

Also see for Magnum DS: Instruction leaflet Instruction booklet Instructions Instructional Leaflet

Technical DataEffective: May 1998 Page 11TD.44A.01.T.ECutler-Hammer Magnum DSMetal-EnclosedLow-Voltage SwitchgearApplicationUnit SubstationsMost Magnum DS Switchgear Assem-blies are configured as unit substations.A Unit Substation, as referred to in thispublication, is defined as a coordinatedassembly consisting of 3-phase trans-formers with high-voltage incomingline sections and an assembly of low-voltage distribution sections, with thefollowing parameters:Transformer kVA – 112.5 through 3750Low-Voltage – 208, 240, 480 or 600 VUnit Substations may be indoor or out-door, with a selection of high-voltageincoming sections, a choice of trans-former types and an arrangement ofMagnum DS Switchgear to suit theapplication.Why Unit Substations?Unit substations follow the systemconcept of locating transformers asclose as practicable to areas of loadconcentration at utilization voltages,thus minimizing the lengths ofsecondary distribution cables andbuses. This concept provides severalbasic advantages, such as:n Reduced power lossesn Improved voltage regulationn Improved service continuityn Reduced likelihood of faultsn Increased flexibilityn Minimized installation expensen Availability of non-flammable typesof transformers eliminates necessityof vaultsn Efficient space utilizationAdvantages of Magnum DS UnitSubstationsn Complete coordination, bothmechanical and electricaln Extreme flexibility with wide choiceof components and ratings to meetexact application requirementsn Optimum safety to operatorsn Modern designn Meets all applicable ANSI, IEEE,NEMA and UL StandardsTransition SectionsAll indoor Unit Substations utilizingliquid filled transformers require an11-inch (279 mm) or 22-inch (559 mm)wide transition section. The center-linelocation of the Iow-voltage throat isbased upon the depth of the MagnumDS assembly.In many indoor applications, it is desir-able to minimize floor space by elimi-nating the need for a transformertransition section. For these situations,Magnum DS switchgear is designed toaccommodate close coupling to drytype transformers if their low-voltageterminations conform to a specific ver-tically oriented arrangement. This con-figuration may be provided if: (1)additional space is not required forauxiliary devices such as groundingresistors, instrumentation, etc.; (2) zerosequence ground fault is not appliedon main breakers; (3) connection toassemblies with no main breaker donot utilize “A” or “B” position feederbreakers; (4) adequate conduit space isavailable for any top exit cable connec-tions in this section.www . ElectricalPartManuals . com