英语翻译
1.Voltages
a.General.
RefertoANSIStandardC84.1forvoltageratingsfor60Hzelectricpowersystemsandequipment.Inaddition,thestandardlistsapplicablemotorandmotorcontrolnameplatevoltagerangesuptonominalsystemvoltagesof13.8kV.
b.Generators.
Terminalvoltageratingsforpowerplantgeneratorsdependonthesizeofthegeneratorsandtheirapplication.Generally,thelargerthegenerator,thehigherthevoltage.GeneratorsforapowerplantservinganArmyinstallationwillbeintherangefrom4160voltsto13.8kVtosuitthesizeoftheunitandprimarydistributionsystemvoltage.Generatorsinthissizerangewillbeofferedbythemanufacturerinaccordancewithitsdesign,anditwouldbedifficultandexpensivetogetadifferentvoltagerating.Insofaraspossible,thegeneratorvoltageshouldmatchthedistributionvoltagetoavoidtheinstallationofatransformerbetweenthegeneratorandthedistributionsystem.
c.Powerplantstationservicepowersystems.
(1)Voltagesforstationservicepowersupplywithinsteamelectricgeneratingstationsarerelatedtomotorsizeand,toalesserextent,distancesofcableruns.Motorsizesfordraftfansandboilerfeedpumpsusuallycontroltheselectionofthehigheststationservicepowervoltagelevel.Rulesforselectingmotorvoltagearenotrigidbutarebasedonrelativecosts.Forinstance,ifthereisonlyonemotorlargerthan200hpanditis,say,only300hp,itmightbeagoodchoicetoselectthisonelargermotorfor460voltssothattheentireauxiliarypowersystemcanbedesignedatthelowervoltage.
(2)Stationservicepowerrequirementsforcombustionturbineandinternalcombustionenginegeneratingplantsaresuchthat208or480voltswillbeused.
d.Distributionsystem.
TheprimarydistributionsystemforanArmyinstallationwithcentralinhousegenerationshouldbeselectedinaccordancewithTM5-811-l/AFM88-9.