power distribution - Siemens

Secondary Unit SubstationsOverviewGeneralSiemens offers a wide variety of unitsubstation designs to meet customerrequirements. A unit substation consistsof one or more transformersmechanically and electrically connectedto and coordinated in design with one ormore switchgear or switchboardassemblies. A secondary unit substationis defined as a unit substation whoseoutgoing section is rated below 1000volts.A typical secondary unit substationconsists of three sections:▪ Primary: an incoming section thataccepts incoming high voltage (2400 to13,800 volts) line▪ Transformer: section that transformsincoming voltage down to utilizationvoltage (600 volts or less)▪ Secondary: an outgoing section thatdistributes power to outgoing feedersand provides protection for thesefeeders (600 volts and less)Standard secondary unit substationsconsist of:▪ Medium Voltage Primary▪ Transformer▪ Low Voltage SecondarySiemens also offers low voltage unitsubstations with:▪ Low Voltage Primary▪ Transformer▪ Low Voltage SecondaryThe primary reason for using a secondaryunit substation is to bring power as closeas possible to the center of the loads.Another reason is that it provides asystem design concept incorporating awide variety of components that permitstailoring equipment to the needs of theapplication. A secondary unit substationprovides▪ Reduced power losses▪ Better voltage regulation▪ Improved service continuity▪ Increased functional flexibility▪ Lower installation cost▪ Efficient space utilizationEvery component and assembly ofsecondary unit substations are designedand engineered as an integral part of acomplete system.Primary SwitchPrimary SwitchLiquid Filled TransformerDry Type TransformerSwitchboard with WL EncasedSystems BreakersType SB3 Switchboard withFusible Switches13 SWITCHGEARPrimary SwitchLiquid Filled TransformerType WL Low VoltageSwitchgearFor more information, please visit http://automation.usa.siemens.com/consultant/ or contact your local sales office.Siemens Power Distribution & Control, SPEEDFAX 2007-2008 Product Catalog 13-37