� AN0032/A� July2008Copyright©2008byACTechnology www.lenze-actech.com �-508-278-9�00 Forgeneralinformationonly.Contentsubjecttochangewithoutnotice.

Application Note

Inputandoutputreactorsserveverydifferentpurposes.Simplyput,aninputreactorprotectsthedriveandanout-putreactorprotectsthemotor.However,thereareafewmoredetailstodeterminethecorrectapplication.

Input (Line) Reactors

Aninputorlinereactorhelpsprotectavariablefrequencydrive(VFD)frominputpowerlinedisturbancesthatcouldcausenuisancetrippingordamagetothedrive.Aninput(line)reactoralsoreducestheharmonicsthattheVFDgeneratesbackontotheline.LinereactorsaresizedbasedontheHPandvoltageratingsofthedriveinuse.Lenze-ACTechuses3%or5%reactors.Input(line)reactorsshouldbeusedinthesecircumstances:

Theinputlinepowerispronetohavedisturbancessuchassurges,spikes,transients,etc.

Thesupplylinepowerisverystiff(greaterthan�0timesthekVAratingoftheconnectedVFD).

Whereharmonicdistortionisaconcern.(IEEE-5�9HarmonicControlinElectricalPowerSystems)

LinereactorsareconnectedinseriesbetweentheinputsourceandtheVFDController.RefertoFigure�forproperwiringinstallation.Thereactorshouldbemountedasclosetothedriveaspossible.

Input Fuse

Input Fuse

Input Fuse

Controller

A1 A2

MotorB1 B2

C1 C2

Input Line Reactor

Figure�:Input(Line)Reactor

3% Impedance Line Reactors

3%impedancelinereactorsshouldbeusedtoreducepowerlinetransientvoltagescausedbycapacitorswitching,linenotching,DCBusover-voltagetrippingandinverterover-currentandover-voltageconditions.Theyimprovethetrueinputpowerfactorandreducecross-talkbetweendrives.

Theinput(line)reactorofferssomeprotectiontothedriveinshort-circuitconditions.IfthesupplytransformerkVAratingisgreaterthantentimesthedrivekVArating,thenalinereactorisrecommendedtominimizedamagetothedriveincasethesupplytransformerevershortsout.Thislineimpedanceisdependentontheshort-circuitratingforthedriveandonthesupplypowerdistributiontransformer.Specifically,thelineimpedancemustbegreaterthanorequaltotheratioofthesupplysourcetransformer’sratingtothedrive’sshortcircuitrating.

Forexample,let’ssayyouhavea�00kVA,460V,�20Apowertransformerforyoursourceandinstalla3%linereactorinfrontofanMCseriesdrive*.Thismeansforthesimplestcalculation,theavailableshort-circuitcurrentwouldbe�20A/.03=4000Amps.ThisislessthantheMCseries5000Aratingsothe3%linereactorwouldworkfine.Youcanmakethissamecalculationbydeterminingthecurrentofthesupplytransformerandthelinereactorimpedance.

*Thesourcetransformer'simpedanceisnotincludedbecausethedifferenceinsizemakesitnegligible.

�.

2.

3.

WhentoUseaLineorLoadReactorProtectingtheDriveortheMotor

2 AN0032/A� July2008Copyright©2008byACTechnology www.lenze-actech.com �-508-278-9�00 Forgeneralinformationonly.Contentsubjecttochangewithoutnotice.

Application Note

5% Impedance Line Reactors

5%impedancelinereactorshavethesamebenefitsasthe3%reactorsplustheyprovidemaximumharmonicmiti-gationwithoutaddedcapacitance.Theseharmonicsignalsproducedistortionlevelsthatmaynotbeacceptableforcertainhighfrequencyornoisesensitiveequipment.UseofthemwillhelptocomplywiththeIEEE5�9Standardandreducemotoroperatingtemperatureandmotornoise.

Multiple Input (Line) Reactors

Inapplicationsinvolvingmultipledrivesinparallel,havingmorethanoneVFDconnectedtoacommonpowerlinerequiresonelinereactorperdrive.IndividualreactorswillprovideproperfilteringandoptimumsurgeprotectionforeachVFDandreducecrosstalkbetweeneachunit.AsinglereactorconnectedtomultipleVFDsdoesnotprovideadequateprotection,filteringorreduceharmonicdistortionwhenthesystemispartiallyloaded.

Eachlinereactor isconnectedinseriesbetweentheinputsourceandtheVFDController.RefertoFigure2forproperwiringinstallation.Eachsetofinputlinestothedriveshouldbeinitsownseparatesteelconduit.Thereactorshouldbemountedasclosetothedriveaspossible.

Input Fuse

Input Fuse

Input Fuse

Controller

A1 A2

MotorB1 B2

C1 C2

Input Fuse

Input Fuse

Input Fuse

Controller

A1 A2

MotorB1 B2

C1 C2

Input Line Reactors

Figure2:MultipleInput(Line)Reactors

Output (Load) Reactors

Anoutput(load)reactor,ontheotherhand,isusedtoprotectthemotorifthewiringdistancebetweentheVFDandmotorisverylong.ThedrivegeneratesahighfrequencyPWMthree-phaseoutputandnoisespikesaregeneratedontheleadingedgeofthesesignals.Thesenoisespikesgetamplifiedduetothelongcablelengthsandthead-ditionalcapacitanceofthecable.Theresultingvoltagecanexceedthemotor’speakvoltageratingwhereinsulationbreakdownoccurs.

Thegeneralruleofthumbisthatanoutputreactorshouldbeusedifthemotorwiringisover�00feet,butthisvaluevariesdependingonthemotor.IfthemotormeetstheNEMAMG-�Part3�standard,itispossibletohaveasmuchas300ftofcablingwithoutareactor.Ifitdoesnotmeetthestandard,themaximumcablelengthshouldbe�00ft.Also,ifthedistanceisbetween300and500ft,aloadreactormustbeinstalled.

3 AN0032/A� July2008Copyright©2008byACTechnology www.lenze-actech.com �-508-278-9�00 Forgeneralinformationonly.Contentsubjecttochangewithoutnotice.

Application Note

If thedistance isbetween500and�000ft,youwoulduseaspecial typeoffiltercalledadV/dTfilter,astheyprovidebetterprotectionattheseextremedistances.Thisalsovariesdependingonoutputcablespecs,shielding,powerconditions,andnoisesuppressionaswellasisolationtechniques.

LoadreactorsareconnectedinseriesbetweentheVFDControllerandthemotor.RefertoFigure3forproperwiringinstallation.Thereactorshouldbemountedasclosetothedriveaspossible.

Input Fuse

Input Fuse

Input Fuse

Controller

A1 A2

MotorB1 B2

C1 C2

Output Load Reactor

Figure3:OutputLoadReactor

Multiple Motors

Foranapplicationinvolvingmorethanonemotorbeingcontrolledbyasingledrive,asinglereactorcantypicallybeusedbetweentheVFDandthemotors.Notethateachmotorrequiresaseparatethermaloverloadforproperprotection.Thereactorshouldbesizedbasedonthetotalmotor/loadhorsepower.

TheloadreactorisconnectedinseriesbetweentheVFDControllerandthemotors.RefertoFigure4forproperwiringinstallation.Eachsetofmotorcablesshouldbeinaseparatesteelconduittoavoidnoiseandcrosstalkthatcancausenuisancetripping.Thereactorshouldbemountedasclosetothedriveaspossible.

Input Fuse

Input Fuse

Input Fuse

Controller

A1 A2

MotorB1 B2

C1 C2

Motor

Output Load Reactor

Figure4:Output(Load)Reactor&MultipleMotors