1.Voltages

　　电压

　　a.General.

　　概述

　　RefertoANSIStandardC84.1forvoltageratingsfor60Hzelectricpowersystemsandequipment.Inaddition,thestandardlistsapplicablemotorandmotorcontrolnameplatevoltagerangesuptonominalsystemvoltagesof13.8kV.

　　60Hz电力系统和设备的额定电压,参见ANSI标准C84.1.另外,该标准列出了标称系统电压不超过13.8kv的适用发动机（电机）和发动机控制铭牌电压.

　　b.Generators.

　　发电机

　　Terminalvoltageratingsforpowerplantgeneratorsdependonthesizeofthegeneratorsandtheirapplication.Generally,thelargerthegenerator,thehigherthevoltage.GeneratorsforapowerplantservinganArmyinstallationwillbeintherangefrom4160voltsto13.8kVtosuitthesizeoftheunitandprimarydistributionsystemvoltage.Generatorsinthissizerangewillbeofferedbythemanufacturerinaccordancewithitsdesign,anditwouldbedifficultandexpensivetogetadifferentvoltagerating.Insofaraspossible,thegeneratorvoltageshouldmatchthedistributionvoltagetoavoidtheinstallationofatransformerbetweenthegeneratorandthedistributionsystem.

　　发电机及其应用.通常,发电机越大,则电压越高.供应军事装置的电厂发电机电压在4160伏到13.8千伏,适合机组和一级（主要）配电系统电压.该规格范围的发电机由制造商根据其设计予以提供.选用其它额定电压则比较困难而且价格昂贵.发电机电压应尽可能与配电电压匹配,省去在发电机和配电系统之间加装变压器的需要.

　　c.Powerplantstationservicepowersystems.

　　电站供电系统

　　(1)Voltagesforstationservicepowersupplywithinsteamelectricgeneratingstationsarerelatedtomotorsizeand,toalesserextent,distancesofcableruns.Motorsizesfordraftfansandboilerfeedpumpsusuallycontroltheselectionofthehigheststationservicepowervoltagelevel.Rulesforselectingmotorvoltagearenotrigidbutarebasedonrelativecosts.Forinstance,ifthereisonlyonemotorlargerthan200hpanditis,say,only300hp,itmightbeagoodchoicetoselectthisonelargermotorfor460voltssothattheentireauxiliarypowersystemcanbedesignedatthelowervoltage.

　　蒸汽发电电站内部供电电压与发动机规格有关,而与电缆布线距离的关系稍微远一点.抽风机和锅炉给水泵的电动机规格通常决定了电站的最高供电电压.发动机电压选择规则并不严格,而是根据相对成本.例如,如果只有一台200hp以上的发动机,比如只有300hp,那么最好将该更大的发动机用于460伏,从而整个辅助电力系统（厂用电系统）可以在更低的电压水平进行设计.

　　(2)Stationservicepowerrequirementsforcombustionturbineandinternalcombustionenginegeneratingplantsaresuchthat208or480voltswillbeused.

　　关于燃气轮机和内燃发动机发电厂的电站供电电压要求,将使用208或480伏.

　　d.Distributionsystem.

　　配电系统

　　TheprimarydistributionsystemforanArmyinstallationwithcentralinhousegenerationshouldbeselectedinaccordancewithTM5-811-l/AFM88-9.

　　中心内部发电（这句不能肯定）的军事装置的一级（主要）配电系统按照TM5-811-1/AFM88-9选择.