JosephUKDepartmentofMiningEngineeringJuly21,20167200V或?????

????

v(t瞬時(shí)電壓值Vm峰值電壓

?? ?

??w2pf(每秒f=頻率Hz,T=?周期

16 t,綜述我們?yōu)槭裁词褂孟嗔繒r(shí)間恒在相量域中時(shí)域的微分和積分變成代數(shù)運(yùn)算（通過(guò)復(fù)數(shù)系數(shù)什么情況下我們考慮使用相恒穩(wěn)態(tài)（恒定的振幅、周期和相位綜述考慮電時(shí)間函數(shù):v ???170? ??????相量值

????

/90°??有效值

|???

(適用于當(dāng)前綜述通過(guò)電感，電抗‐Xl和阻抗‐ZLXLwL感抗ΩZLjwL阻抗通過(guò)電容,電阻‐XC和阻抗‐ZC

=??容抗Ω??=??阻抗??綜述下面的示意圖中,??? ???14.14Cos1000?

I2,a

3mH綜述????10.0/90°

??????14.14Cos1000 ? ??

??

????????????????Ω?? ?

??

??Ω

1.64/13.67°綜述等效電阻分流

??????14.14Cos1000

?

?

???

0.98/66.80

1.31/??23.20?????????Ofcourse,???=

???????cos?

????

????cos?Voltage,Voltage,Current,420

R,L,or?S=VI*=|I|2Z=|V|2/Z*=P+V=I*=S復(fù)功率,衡量表觀功率VA(復(fù)數(shù)|S|視在功率,等于S的大小,(|S|瞬時(shí)總功率振蕩分量的大小P平均值,有效值或有效功率,以瓦特為單位,Q無(wú)功的振幅,以視在功率測(cè)量,For

0.50?

??

????170

3.00

4.0 3.0

4 0.50 .7?

91.219/37.24°A? ???|?|

?????

交流電源功率因子,pf,是被定義為視在功率為平均功率比率.在系統(tǒng)中是純正弦波，功率因子也 ????????因?yàn)镃os 當(dāng)Q是正的,

交流電源功率三角形(R+

??????

???????????

SQ θ???‐P每個(gè)源之間的相位是1/3循環(huán)(i.e.,120)電壓用來(lái)平衡每三條線(xiàn)的抗組,以此來(lái)電流平衡(i.e.,equalmagnitudewitha120phaseshift)相位利用a,b,和c標(biāo)記;相位序列是a‐b‐c(i.e.,phasealeadsphasebby andbleadsphasecby120

星型 三角型(使用星型連接電源電壓Vab,Vbc,Vca是直接或通

a

n –

b

–

–線(xiàn)電流等于相電流IaIb,

–c

–

–

a

b電流是IaIb,相位電流是IabIbc,

–

cc

三相系統(tǒng) ??? ??

a a

––

–

–c三相系統(tǒng)ByKirchhoff’s現(xiàn)行??

–???c???0 c?????????????

????

?–?????

–

–

b三相系統(tǒng)Z=Zb

=Z1Z2+Z2Z3+Z3Za+Zb

=Z Za =ZZa+Zb+Zc

Z1Z2+Z2Z3+Z3=Z Z=ZZ3

Za Za+Zb+Z

Z1Z2+Z2Z3+Z3=ZZ=Z Za=Zb=?1?=

Z1=Z2=Za=Zb=Zc=

?????平衡電壓:等于120平衡阻抗ZaZb=ZcZ1=Z2=每個(gè)相位等功率SaSb=這這種情況下,程序?qū)⒔o定電路轉(zhuǎn)換為一個(gè)等效Y,對(duì)等效Y三相電路中一個(gè)相位進(jìn)行分析(e.g.,a相位)oftheequivalent‐wye通常的，分析相位a;如果沒(méi)有制定相位角就使用Va利用單相的結(jié)果,計(jì)算其他相位的值(e.g.,線(xiàn)線(xiàn)電壓,三相電源A480V(line‐to‐line)wye21.0/30°Ωdelta連接通一個(gè)線(xiàn)路阻抗負(fù)荷(0.10+j0.50)Ω.一個(gè)480V(線(xiàn)線(xiàn)相連)wye21.0/30°Ω連接負(fù)荷通過(guò)一個(gè)線(xiàn)路阻抗(0.10+解電壓

?? ??????????277.1 Va277.1/0°負(fù)載阻抗:負(fù)荷是deltaZD=21.0/30° ??? ????7.0/30°=(6.06認(rèn)為VnVn’

an分析三相中的一相(phasea),等效wye ???

???

?????.? ? 31.36/33.0°

37.73/??33.0°

???

31.36/33.0°

37.73/??33.0°

???????37.73/??33.0°? ????

???

???31.36/33.0°n

37.73/??33.0°

29.89/30.0°31.36/33.0°??29.89/30.0°??? ???3??

??0.50???三相回路很難去畫(huà)和讀

D說(shuō)明單線(xiàn)說(shuō)明單相關(guān)聯(lián)等值Y回

擴(kuò)

典型分布電壓4160720012,470

13,200/13,800480104023004160

礦山電力系統(tǒng)的主要組成輸入電壓13.2kV–230尺寸大小通常為kVA一個(gè)每連接(0.746設(shè)備接地過(guò)流（或零序）15.5kV,600AVacuumCircuit 額定到30最高放電電普通式(在互感器二次使用額定120中等放電電額定到684最低電Substationone‐line

PowerPower51- GroundContinuityPower

Y59-

PilotGroundingMAJORCOMPONENTSOFMINEPOWERSYSTEMS‐SwitchhousesallowthesystemtobranchandprovideprotectiontooutgoingCircuitprotectionissimilartothatofSwitchhousemayalsocontainafeedthrough(unprotectedoutputLidinterlocksprevententrytoenergizedOne‐lineDiagramofSwitchhouse

Grounding

Ground-CheckPowerConductorsGround-CheckPowerConductorsInterlocksandEmergency 50- 50-MAJORCOMPONENTSOFMINEPOWERSYSTEMS‐Primary

MAJORCOMPONENTSOFMINEPOWERSYSTEMS–POWERTransformdistributionvoltagetoutilizationProvideprotected,outgoingcircuitsformachinesandCanbethoughtofasaportablesubstationMajorComponentsInputandoutputTransformerandneutralgroundingSurgeCircuit

MAJORCOMPONENTSOFMINEPOWERSYSTEMS–POWERDesignedforthefollowingsequenceofcontactsbeingdisconnectedGroundcheckPowerGroundConvertsdistributionvoltageleveltoutilizationvoltagelevelFrequentlyadry‐typetransformer(i.e.,aircooled)isusedNeutralgroundingresistorlimitsgroundfault

500kVA,three‐phaseLoadBreak

MAJORCOMPONENTSOFMINEPOWERSYSTEMS–POWERUsedtodisconnectpowerfromthetransformerDesignedtointerruptcurrentsequaltheloadbeakswitchcontinuouscurrent15kV,600‐Avacuumloadbreak

MAJORCOMPONENTSOFMINEPOWERSYSTEMS–POWERAswithsubstation,usedtoprotecttransformerSurgeArrestersTypicallyconnectedfromtransformerprimaryterminalstosubstationframeCircuitBreakersUsedtoprotecteachoutgoingcircuitfromfaultsandOften,theyaremolded‐caseSensingandinterruptionelementsinthecircuitArcisextinguishedinairinsteadofavacuumorOne‐linediagramofpowerMAJORCOMPONENTSOFMINEPOWERSYSTEMS–POWERPhotooflarge,undergroundcoal‐minepowerMINEPOWERTypesofBoreholeCable–CabledesignedtobesuspendedverticallyinaboreholeorMinePowerFeeder–Cabledesignedforundergroundhighvoltagedistributionwherethecableismovedinfrequently(lessthanonceayear)PortableorTrailingCable–CableconnectedtominemotorsorCurrent‐carryingcomponentofa

MINEPOWERCABLESIncludepowerconductorsandgroundingMayincludeground‐checkconductor(moreComposedofnumeroussmallwiresboundtogetherinstrandstoimproveMINEPOWERCableSeparatesconductorsandkeepscurrentinitsintendedUsedonpowerandground‐checkconductors(moreonground‐checkCommoninsulatingEthylene‐propylenerubberCrosslinkedpolyethylenePolyvinylchlorideReducesvoltagestressontheConfinestheelectricfieldtotheinsulationTypesofshieldingStrand

MINEPOWERCABLESSurroundstheconductorandisfirmlybondedtothePurposeistoreduceoreliminatethevoltagestressinvoidsbetweentheconductorandInsulationSurroundstheconductorConfineselectricfieldtoconductorHelpstopreventphase(line)

MINEPOWERCABLESHoldstheinnercomponentsofthecable ProvidesprotectionforothercableJacketmustberesistanttoabrasion,crushing,tearing,moisture,chemicals,andsunlight(UV)JacketNeoprene,achloropreneChlorinatedPolyethylene(CPE);tough,durable;itcanbemadeindifferent sticPolyurethane(TPU)forextremelyabrasiveenvironments;resistanttoUV;remainsflexibleinlowtemperaturesFillsvoidsbetweeninMINEPOWERCABLES–CABLELettersusedincableGContainsuninsulatedgroundingWWithoutuninsulatedgroundingIncludesinsulatedground‐check(pilot)ShieldedDMultipleinsulationCOneinsulationMinepowerCrosssectionsofdifferenttypesofminecablesBasedonfourCable

MINEPOWERCABLES–CurrentcarryingabilityofpowerBasedontheabilityofthecabletodissipateTypicallybasedon40°Cambientand90°CconductorVoltagedropinShort‐circuitwithstandofFederalConductorroundandflat,0‐5,000Vunshielded3‐conductor0Conductorroundandflat,0‐5,000Vunshielded3‐conductor0‐8,0008,00115,00015,00125,0008———6——4——3——21——————————Basedonacopperconductortemperatureof90°Candanambientairtemperatureof400CConductor2,001–8,0008,001Conductor2,001–8,0008,001–15,0006————422—————————Basedonacopperconductortemperatureof90°CandanambientairtemperatureofNOTE—DashindicatescableisnotVoltageRegulation

CABLESELECTION– ?|???|=thermsfullload|???|=thermsnoload

?

???Voltageregulationshouldbelimitedto±10%ofmachine(motor)CableSelection–ShortCircuitWithstandRequiresdetailedsystemshort‐circuitGround(groundConductingconnectionbywhichanelectriccircuitorequipmentisconnectedtotheearth,orsomelargeconductingbodythatservesin ceoftheearthUsedtoestablishandmaintainthepotentialoftheearthonconductorsconnectedtoitWhyGround?limitvoltagesduetolightning,linesurges,orunintentionalcontactwithhighervoltagestabilizevoltageduringnormalprovidelowimpedancepathforReduceelectricalLowimpedancepathforgroundfaultcurrentEasytodetectfault(highcurrent)WhatproblemsdoyouNolow‐impedancepathforground‐faultDifficulttodetectgroundfaultShockDependingonconditions,theonlyreturnpathforfaultcurrentmaybetheTYPESOFGROUNDINGUngroundedSystemNolosttimeonfirstgroundfaultNoovervoltageGroundfaultprotectionisdifficultSecondfaultisTYPESOFGROUNDINGSolidlyGroundedSystemEasytodetectgroundHighgroundfaultTrickyMayloseTYPESOFGROUNDING

CanlimitgroundfaultRequiressensitivegroundfaultdetectionGROUNDEDPreferredmethodofsystemgroundingRequiredforUScoalminesPrimaryreduceelectric‐shockhazardsto nelcausedbyhighframepotentialsduringagroundreducethearcblastincloseproximitytothegroundreduceburningandmeltinginfaultedelectricequipment,suchasswitchgear,transformers,cables,androtatingmachinesreducemechanicalstresses(causedbymagnetic s)incircuitsandapparatuscarryingfaultcurrentscontrolofreducethemomentaryline‐voltagedipcausedbytheoccurrenceandclearingofagroundGROUNDEDSYSTEMASPRACTICEDINUSCOALLow(≤660V)andmedium(661Vto1000V)Limitneutralgroundresistor(NGR)currentto25Neutralgroundingresistormustbeinsulatedforline‐to‐lineNeutralgroundresistormustberatedfor umgroundfaultcurrentCircuitmustbede‐energizedat40%oftheNGRlimit,i.e.,10Highvoltage(>1000

GROUNDEDSYSTEMASPRACTICEDINUSCOALLimitvoltagedropinthegroundcircuitexternaltotheNGR(groundconductors)tonotmorethan100VNeutralgroundingresistormustbeinsulatedforline‐to‐lineNeutralgroundresistorpowerratingmustberatedcontinuousfor groundfaultcurrentInThe100VlimitismetbylimitingNGRcurrentto25issetat10ONELINEDIAGRAMOFUTILITYANDPPriRatedVoltage230000VSSecRatedVoltage12470GROUNDWIREInsomeapplications,continuousmonitoringofgroundwireisrequiredTwotype