NERC Reliability Coordinator Exam Vocabulary (A+ GRAD
o o o o o o
ED)
AcceleratingoPowerocorrectoanswersoInoaoGENERATOR,otheodifferenceobetweenotheoMECHANIC
ALoINPUToPOWERoandotheoelectricalooutputoPOWERo(assumingonooLOSSES).oForoaoGENERAT
OR'soTORQUEoANGLEotoochange,otheoGENERATORomustohaveoacceleratingoPOWER.
AccumulatedoInadvertentocorrectoanswersoTheoaccumulationooverotimeoofoINADVERTENToENER
GY.oTheoaccumulatedoinadvertentoaccountoofoaoBALANCINGoAUTHORITYorepresentsotheoamou
ntoofoexcessoENERGYoaoBALANCINGoAUTHORITYohasoeitherosuppliedotootheoINTERCONNEC
TIONooroabsorbedofromotheoINTERCONNECTION.oBALANCINGoAUTHORITIESomonitorothei
roaccumulatedoinadvertentotooensureotheoaccountsodoonotogrowotooolarge
ActiveoPowerocorrectoanswersoTheocomponentoofotheoCOMPLEXoPOWERothatoperformsotheowork.
oTheocommonounitoofoactiveopoweroisotheoMWoandotheosymbol oiso"P".oActiveopoweroisosometimesoca
lledoREALoPOWER.
ActualoInterchangeocorrectoanswersoTheometeredoINTERCHANGEooveroaospecificoINTERCONN
ECTIONobetweenotwooPHYSICALLYoADJACENToBALANCINGoAUTHORITIES.
ActualoLoadocorrectoanswersoTheoactualoMWodrawnobyoaoLOADofromotheoPOWERoSYSTEM.oTheo
actualoloadowillobeodifferentofromotheoratedooroNOMINALoLOADoifotheoLOAD'soVOLTAGEooroFR
EQUENCYovaryofromotheiroNOMINALovalues
AdequacyocorrectoanswersoTheoabilityoofotheoelectricoSYSTEMotoosupplyotheoaggregateoelectricaloD
EMANDoandoENERGYorequirementsoofotheoend-
useocustomersoatoallotimes,otakingointooaccountoSCHEDULEDoandoreasonablyoexpectedounSCHED
ULEdoOUTAGEsoofoSYSTEMoELEMENTS.ua
AdequateoRegulatingoMarginocorrectoanswersoTheominimumoon-
lineoCAPACITYothatocanobeoincreasedoorodecreasedotooallowotheoSYSTEMotoorespondotooalloreason
ableoDEMANDochangesoinoorderotoobeoincomplianceowithotheoCONTROLoPERFORMANCEoSTA
NDARDS.
,AdjacentoBalancingoAuthoritiesocorrectoanswersoAoBALANCINGoAUTHORITYoAREAothatoisoint
erconnectedotooanotheroBALANCINGoAUTHORITYoAREAoeitherodirectlyooroviaoaomulti-
partyoAGREEMENTooroTRANSMISSIONoTARIFF.
AGCoPulsesocorrectoanswersoTheoAGCoSYSTEMosendsosignalsotooselectedo(regulating)oGENERA
TORSotooadjustotheiroset-
points.oTheseosignalsoareosentoviaotelecommunicationoEQUIPMENT.oTheosignalsoareooftenocalledo
AGCopulses.
Air-
oGapocorrect oanswersoTheoairospaceobetweenotheoROTORoandoSTATORoofoaomotorooroGENERATO
R.
AlternatingoCurrento(AC)ocorrectoanswersoInoACoSYSTEMotheoCURRENToandoVOLTAGEomagni
tudesoconstantlyovaryooroalternate.oCURRENToandoVOLTAGEomagnitudesodoonotoalternateoinoaoD
CoSYSTEM.
AlternatorocorrectoanswersoAoRotatingomachineowhoseooutputoisoalternatingoVOLTAGEoandoCUR
RENT
AluminumoCableoSteeloReinforcedo(ACSR)ocorrectoanswersoAocommonotypeoofoTRANSMISSION
olineoCONDUCTOR othatocomesoinomanyodifferent osizesoandodesigns.oTheoaluminumoisotheoCOND
UCTORoandotheosteeloprovidesostrength.
AmortisseuroWindingocorrectoanswersoAomachineowindingoconsistingoofoaonumberoofoconductingob
arsoattachedobetweenotheomagneticoPOLESoofotheomachine'soROTOR.oAmortisseurowindingsomayob
eousedoasostarterowindingsoorotoohelpodampenoPOWERoOSCILLATIONS
Ampereo(amp)ocorrectoanswersoTheounitoofomeasurementoforoCURRENToflow,ooftenostatedoaso"am
p".
AmplituteocorrectoanswersoTheovalueooromagnitudeothatoaowaveformohasoatoaospecificopointoinotime.
,AnalogoElectronicsocorrectoanswersoElectronicocircuitryoinowhichotheomagnitudesoofoquantitiesoareo
usedoinoaocontinuousomannerotooperformofunctions.oForoexample,oinputoCURRENTovaluesomayobeoa
mplifiedoandousedotooperformoworkoinoanoanalogoCIRCUIT.oAnalogoisodifferentothanodigitaloinotheos
enseothatoanalogoCIRCUITSouseoVOLTAGEoandoCURRENTomagnitudesocontinuouslyowhileodigit
aloCIRCUITSouseoVOLTAGEoandoCURRENTotoodetermineotheostateo(onoorooff)oofoELEMENTS.
AncillaryoServiceso(FERCoDefinition)ocorrectoanswersoThoseoservicesothatoareonecessaryotoosupport
otheoTRANSMISSIONoofoCAPACITYoandoENERGYofromoRESOURCESotooLOADSowhileomaint
ainingoreliableooperationoofotheoTRANSMISSIONoSERVICEoPROVIDER'soTRANSMISSIONoSY
STEMoinoaccordanceowithoGOODoUTILITYoPRACTICE.
AngleoInstabilityocorrectoanswersoTheooppositeoofoANGLEoSTABILITY.oWhenoaoPOWERoSYSTE
MolosesoANGLEoSTABILITYoitoentersoaoPERIODoofoangleoinstability.oAnoangleounstableoSYSTE
MohasolostosomeoportionoofotheomagneticoboundothatoholdsosectionsoofotheoPOWERoSYSTEMoinosyn
chronismowithooneoanother.
AngleoStabilityocorrectoanswersoAnoangleostableoPOWERoSYSTEMoisooneoinowhichoalloELEMENT
SoofotheoPOWERoSYSTEMoareoboundotogetheroviaomagneticoforces.oForoexample,oanoangleostableo
GENERATOR'sointernaloMAGNETICoFIELDorotatesoinosynchronismo(in-
step)owithotheoMAGNETICoFIELDoofotheo3ΦoPOWERoSYSTEMotoowhichoitoconnects.
ApparentoPowerocorrectoanswersoTheoproductoofoVOLTAGEoandoCURRENToPHASORS.oAppare
ntopowerocomprisesobothoactiveoandoREACTIVEoPOWER,ousuallyoexpressedoinoKILOVOLTAMP
EREso(kVA)ooromegavoltampereso(MVA).oAnotherotermoforoapparentopoweroisoCOMPLEXoPOW
ER.
ARCocorrectoanswersoTheodischargeoofoCURRENTothroughotheoairooroinoaogas.
ArcingoHornsocorrectoanswersoAnoenhancementotooaoDISCONNECToSWITCHotooincreaseotheoswit
ch'soCURRENTointerruptingocapability.
AreaoControloAreao(ACE)ocorrectoanswersoTheoinstantaneousodifferenceobetweenonetoactualoandoSC
HEDULEDoINTERCHANGE,otakingointooaccountotheoeffectsoofoFREQUENCYobiasoincludingoaoc
orrectionoforometeroerror.
, ArmatureocorrectoanswersoTheocomponentoofoaomachineoinowhichotheoVOLTAGEoisoinduced.oInoaoS
YNCHRONOUSoGENERATORotheoarmatureoisousuallyotheoSTATOR.oTheoarmatureowindingoisow
rappedoaboutotheoarmature.
AsynchronousocorrectoanswersoToobeoOUT-OF-
STEPowithoaoreference.oAnoinductionoGENERATORoisoanoasynchronousoGENERATORoasoitsoRO
TORodoesonotorotateoinosynchronismowithotheoPOWERoSYSTEM.
Auto-
LoadocorrectoanswersoAofeatureoonosomeoGENERATORSothatoautomaticallyomovesotheoGENERA
TORotooaoTARGEToLOADo(MW)olevel.
AutomaticoGenerationoControlo(AGC)ocorrectoanswersoEQUIPMENTothatoautomaticallyoadjustsoG
ENERATIONoinoaoBALANCINGoAUTHORITYoAREAofromoaocentralolocationotoomaintainotheoB
ALANCINGoAUTHORITY'soINTERCHANGEoSCHEDULEoplusoFREQUENCYoBIAS.oAGCom
ayoalsooaccommodateoautomaticoINADVERTENTopaybackoandoTIMEoERRORoCORRECTION.
AutomaticoOperationsoSystemsocorrectoanswersoSPECIALoPROTECTIONoSYSTEMS,oREMEDI
ALoACTIONoSCHEMEs,oorootherooperatingoSYSTEMsoinstalledoonotheoelectricoSYSTEMsothatore
quireonoointerventionoonotheopartoofoSYSTEMoOPERATORS.
Auto-
TransformerocorrectoanswersoAoPOWERoTRANSFORMERowithoaosingleocoil.oTheoentireocoiloactso
asotheoPRIMARYoWINDINGowhileoaoportionoofotheosameocoiloactsoasotheoSECONDARYoWINDIN
G.
AuxiliaryoRelayocorrectoanswersoAoRELAYowhoseofunctionoisotoosupplementotheoactionsoofootherot
ypesoofoRELAYS.oForoexample,oaoLOCKOUToRELAYoisoanoauxiliaryorelayowithonumerousocontac
tsothatoeachocanoperformoanoaction.oTheoIEEEohasonumbersoassignedotootwootypesoofoauxiliaryorelays
;o86o(lock-out)oando94o(tripping).
AvailabilityocorrectoanswersoAomeasureoofotimeoaogeneratingounit,oTRANSMISSIONoline,ooroothero
FACILITYoisocapableoofoprovidingoservice,owhetherooronotoitoactuallyoisoinoservice.oTypically,othiso
measureoisoexpressedoasoaopercentoavailableoforotheoPERIODounderoconsideration.
o o o o o o
ED)
AcceleratingoPowerocorrectoanswersoInoaoGENERATOR,otheodifferenceobetweenotheoMECHANIC
ALoINPUToPOWERoandotheoelectricalooutputoPOWERo(assumingonooLOSSES).oForoaoGENERAT
OR'soTORQUEoANGLEotoochange,otheoGENERATORomustohaveoacceleratingoPOWER.
AccumulatedoInadvertentocorrectoanswersoTheoaccumulationooverotimeoofoINADVERTENToENER
GY.oTheoaccumulatedoinadvertentoaccountoofoaoBALANCINGoAUTHORITYorepresentsotheoamou
ntoofoexcessoENERGYoaoBALANCINGoAUTHORITYohasoeitherosuppliedotootheoINTERCONNEC
TIONooroabsorbedofromotheoINTERCONNECTION.oBALANCINGoAUTHORITIESomonitorothei
roaccumulatedoinadvertentotooensureotheoaccountsodoonotogrowotooolarge
ActiveoPowerocorrectoanswersoTheocomponentoofotheoCOMPLEXoPOWERothatoperformsotheowork.
oTheocommonounitoofoactiveopoweroisotheoMWoandotheosymbol oiso"P".oActiveopoweroisosometimesoca
lledoREALoPOWER.
ActualoInterchangeocorrectoanswersoTheometeredoINTERCHANGEooveroaospecificoINTERCONN
ECTIONobetweenotwooPHYSICALLYoADJACENToBALANCINGoAUTHORITIES.
ActualoLoadocorrectoanswersoTheoactualoMWodrawnobyoaoLOADofromotheoPOWERoSYSTEM.oTheo
actualoloadowillobeodifferentofromotheoratedooroNOMINALoLOADoifotheoLOAD'soVOLTAGEooroFR
EQUENCYovaryofromotheiroNOMINALovalues
AdequacyocorrectoanswersoTheoabilityoofotheoelectricoSYSTEMotoosupplyotheoaggregateoelectricaloD
EMANDoandoENERGYorequirementsoofotheoend-
useocustomersoatoallotimes,otakingointooaccountoSCHEDULEDoandoreasonablyoexpectedounSCHED
ULEdoOUTAGEsoofoSYSTEMoELEMENTS.ua
AdequateoRegulatingoMarginocorrectoanswersoTheominimumoon-
lineoCAPACITYothatocanobeoincreasedoorodecreasedotooallowotheoSYSTEMotoorespondotooalloreason
ableoDEMANDochangesoinoorderotoobeoincomplianceowithotheoCONTROLoPERFORMANCEoSTA
NDARDS.
,AdjacentoBalancingoAuthoritiesocorrectoanswersoAoBALANCINGoAUTHORITYoAREAothatoisoint
erconnectedotooanotheroBALANCINGoAUTHORITYoAREAoeitherodirectlyooroviaoaomulti-
partyoAGREEMENTooroTRANSMISSIONoTARIFF.
AGCoPulsesocorrectoanswersoTheoAGCoSYSTEMosendsosignalsotooselectedo(regulating)oGENERA
TORSotooadjustotheiroset-
points.oTheseosignalsoareosentoviaotelecommunicationoEQUIPMENT.oTheosignalsoareooftenocalledo
AGCopulses.
Air-
oGapocorrect oanswersoTheoairospaceobetweenotheoROTORoandoSTATORoofoaomotorooroGENERATO
R.
AlternatingoCurrento(AC)ocorrectoanswersoInoACoSYSTEMotheoCURRENToandoVOLTAGEomagni
tudesoconstantlyovaryooroalternate.oCURRENToandoVOLTAGEomagnitudesodoonotoalternateoinoaoD
CoSYSTEM.
AlternatorocorrectoanswersoAoRotatingomachineowhoseooutputoisoalternatingoVOLTAGEoandoCUR
RENT
AluminumoCableoSteeloReinforcedo(ACSR)ocorrectoanswersoAocommonotypeoofoTRANSMISSION
olineoCONDUCTOR othatocomesoinomanyodifferent osizesoandodesigns.oTheoaluminumoisotheoCOND
UCTORoandotheosteeloprovidesostrength.
AmortisseuroWindingocorrectoanswersoAomachineowindingoconsistingoofoaonumberoofoconductingob
arsoattachedobetweenotheomagneticoPOLESoofotheomachine'soROTOR.oAmortisseurowindingsomayob
eousedoasostarterowindingsoorotoohelpodampenoPOWERoOSCILLATIONS
Ampereo(amp)ocorrectoanswersoTheounitoofomeasurementoforoCURRENToflow,ooftenostatedoaso"am
p".
AmplituteocorrectoanswersoTheovalueooromagnitudeothatoaowaveformohasoatoaospecificopointoinotime.
,AnalogoElectronicsocorrectoanswersoElectronicocircuitryoinowhichotheomagnitudesoofoquantitiesoareo
usedoinoaocontinuousomannerotooperformofunctions.oForoexample,oinputoCURRENTovaluesomayobeoa
mplifiedoandousedotooperformoworkoinoanoanalogoCIRCUIT.oAnalogoisodifferentothanodigitaloinotheos
enseothatoanalogoCIRCUITSouseoVOLTAGEoandoCURRENTomagnitudesocontinuouslyowhileodigit
aloCIRCUITSouseoVOLTAGEoandoCURRENTotoodetermineotheostateo(onoorooff)oofoELEMENTS.
AncillaryoServiceso(FERCoDefinition)ocorrectoanswersoThoseoservicesothatoareonecessaryotoosupport
otheoTRANSMISSIONoofoCAPACITYoandoENERGYofromoRESOURCESotooLOADSowhileomaint
ainingoreliableooperationoofotheoTRANSMISSIONoSERVICEoPROVIDER'soTRANSMISSIONoSY
STEMoinoaccordanceowithoGOODoUTILITYoPRACTICE.
AngleoInstabilityocorrectoanswersoTheooppositeoofoANGLEoSTABILITY.oWhenoaoPOWERoSYSTE
MolosesoANGLEoSTABILITYoitoentersoaoPERIODoofoangleoinstability.oAnoangleounstableoSYSTE
MohasolostosomeoportionoofotheomagneticoboundothatoholdsosectionsoofotheoPOWERoSYSTEMoinosyn
chronismowithooneoanother.
AngleoStabilityocorrectoanswersoAnoangleostableoPOWERoSYSTEMoisooneoinowhichoalloELEMENT
SoofotheoPOWERoSYSTEMoareoboundotogetheroviaomagneticoforces.oForoexample,oanoangleostableo
GENERATOR'sointernaloMAGNETICoFIELDorotatesoinosynchronismo(in-
step)owithotheoMAGNETICoFIELDoofotheo3ΦoPOWERoSYSTEMotoowhichoitoconnects.
ApparentoPowerocorrectoanswersoTheoproductoofoVOLTAGEoandoCURRENToPHASORS.oAppare
ntopowerocomprisesobothoactiveoandoREACTIVEoPOWER,ousuallyoexpressedoinoKILOVOLTAMP
EREso(kVA)ooromegavoltampereso(MVA).oAnotherotermoforoapparentopoweroisoCOMPLEXoPOW
ER.
ARCocorrectoanswersoTheodischargeoofoCURRENTothroughotheoairooroinoaogas.
ArcingoHornsocorrectoanswersoAnoenhancementotooaoDISCONNECToSWITCHotooincreaseotheoswit
ch'soCURRENTointerruptingocapability.
AreaoControloAreao(ACE)ocorrectoanswersoTheoinstantaneousodifferenceobetweenonetoactualoandoSC
HEDULEDoINTERCHANGE,otakingointooaccountotheoeffectsoofoFREQUENCYobiasoincludingoaoc
orrectionoforometeroerror.
, ArmatureocorrectoanswersoTheocomponentoofoaomachineoinowhichotheoVOLTAGEoisoinduced.oInoaoS
YNCHRONOUSoGENERATORotheoarmatureoisousuallyotheoSTATOR.oTheoarmatureowindingoisow
rappedoaboutotheoarmature.
AsynchronousocorrectoanswersoToobeoOUT-OF-
STEPowithoaoreference.oAnoinductionoGENERATORoisoanoasynchronousoGENERATORoasoitsoRO
TORodoesonotorotateoinosynchronismowithotheoPOWERoSYSTEM.
Auto-
LoadocorrectoanswersoAofeatureoonosomeoGENERATORSothatoautomaticallyomovesotheoGENERA
TORotooaoTARGEToLOADo(MW)olevel.
AutomaticoGenerationoControlo(AGC)ocorrectoanswersoEQUIPMENTothatoautomaticallyoadjustsoG
ENERATIONoinoaoBALANCINGoAUTHORITYoAREAofromoaocentralolocationotoomaintainotheoB
ALANCINGoAUTHORITY'soINTERCHANGEoSCHEDULEoplusoFREQUENCYoBIAS.oAGCom
ayoalsooaccommodateoautomaticoINADVERTENTopaybackoandoTIMEoERRORoCORRECTION.
AutomaticoOperationsoSystemsocorrectoanswersoSPECIALoPROTECTIONoSYSTEMS,oREMEDI
ALoACTIONoSCHEMEs,oorootherooperatingoSYSTEMsoinstalledoonotheoelectricoSYSTEMsothatore
quireonoointerventionoonotheopartoofoSYSTEMoOPERATORS.
Auto-
TransformerocorrectoanswersoAoPOWERoTRANSFORMERowithoaosingleocoil.oTheoentireocoiloactso
asotheoPRIMARYoWINDINGowhileoaoportionoofotheosameocoiloactsoasotheoSECONDARYoWINDIN
G.
AuxiliaryoRelayocorrectoanswersoAoRELAYowhoseofunctionoisotoosupplementotheoactionsoofootherot
ypesoofoRELAYS.oForoexample,oaoLOCKOUToRELAYoisoanoauxiliaryorelayowithonumerousocontac
tsothatoeachocanoperformoanoaction.oTheoIEEEohasonumbersoassignedotootwootypesoofoauxiliaryorelays
;o86o(lock-out)oando94o(tripping).
AvailabilityocorrectoanswersoAomeasureoofotimeoaogeneratingounit,oTRANSMISSIONoline,ooroothero
FACILITYoisocapableoofoprovidingoservice,owhetherooronotoitoactuallyoisoinoservice.oTypically,othiso
measureoisoexpressedoasoaopercentoavailableoforotheoPERIODounderoconsideration.
