Eaton Cutler-Hammer Digitrip RMS 910 Instructions Manual

Also see for Digitrip RMS 910: Instructions Instructional Leaflet Instruction leaflet

I.L.29-889APage7Thissignalrequires thatonlyasinglepairofwires beconnectedfromtheinterlock outputterminals of thedownstreambreaker’sTripUnit,tothe interlock inputter-minalsof theupstreambreaker’sTripUnit. For specificinstructions seetheapplicable connectiondiagramsforyourbreaker listedin Section6.Note:Ifabreaker(M)receivesaZone Interlockingsignalfromanother breaker(F) thatis tripping,butthe fault current levelis less than the settingforbreaker(M),thepresenceoftheZone Interlockingsignalfromtheotherbreaker(F)cannotcausebreaker(M) totrip.Ifa circuitbreakerwouldcloseontoahighshort-circuitcurrent,whentheDiscriminatorisinactive,typeLSorLSGTripUnitswillrelyon theshort-time delayfunctionbefore tripping.Ifthefaultcurrentexceedstheshort-timewithstandcurrentcapabilityofthecircuitbreaker,theOverRIDeprotectionfunction willtripthebreakerwithoutdelay.(SeeSection1.1.4.)Also,pleaseseeSection1.1.5forother exceptionswhenZoneInterlockingisemployed.TheDiscriminator(high initialcurrentrelease)canbemadeinactiveby turning the“OVERRIDE/”settingswitch(nearest thebottom edgeoftheTripUnit)fromthe“DIS”position,tothe“[blank]”position.(SeeFigs. 3.2and3.5)Notes:Thisswitchhaseight (8) positions,andseven(7)ofthepositionsshow“DIS”inthewindow,ONLYONE positionshows“[blank]”.When the“OVERRIDE/”window shows“[blank]”,theonlyfast-actinghighshort-circuit protection avail-ableistheOVERRIDE(FixedInstantaneous).(SeeSection 1.1.4.)1.1.4OVERRIDE (Fixed Instantaneous)Each DigitripRMS 910TripUnit has a Fixed Instanta-neous“Override"analog trip circuitpre-settoavaluenogreaterthantheshort-timewithstandcurrent ratingofthecircuitbreaker inwhichtheTripUnit is installed. Sincethespecificvaluesvary fordifferentcircuit breakertypesandratings,refertotime-currentcurves,listedin Section 6,forthe values applicabletoyourbreaker.Ifbreakertripsduetohigh instantaneouscurrent,the“OVERRIDE/”LED will light“RED”,and thedisplay willread“ORID”.CAUTIONIFZONE INTERLOCKINGISNOTTOBEUSED(I.E.STANDARD TIME-DELAY COORDINATIONONLYISINTENDED),THE ZONEINTERLOCKING TERMINALSMUSTBECONNECTED WITH JUMPER WIRES,ASSPECIFIED ON THE CONNECTIONDIAGRAMS FORYOUR BREAKER(SEE SECTION6), SOTHE TIME-DELAYSETTINGS WILL PROVIDETHEINTENDEDCOORDINATION.For examplesofhow ZoneSelectiveInterlockingmaybeused,SeeAppendixA.1.2FourCharacter Information Display WindowThefour-digitalpha-numericdisplay window, illustratedinFigs.1and2,serves twobasic purposes:instrumenta-tion andmode oftripandtrouble indication. The informa-tiondisplayedinthewindowislisted inTables2and3.1.2.1Values Displayed During Normal ServiceThe alpha-numeric display window provides informationalvalues under normal service conditionsand coded mes-sagesafter analarm conditionor afteranover-currenttripoperation. The twelve Green LEDsbelowthe displaywindow indicate which valueofcurrent,voltage,power,power factor, energy,or Total Harmonic Distortion(THD)is being displayed.The value in the display window indi-cates the present valueofthe parameter whose LED islighted“Green".InFig.1,thefirst four“Green”LEDsidentify whichcurrent(kA)value is being displayed,i.e.phaseAcurrent(lA),phase B current(lB),phaseC cur-rent (lc),ground current (lG), orcurrent in the fourth pole(neutral) (lD).The press and release operationofthe“Step” push-button willstepnext to the Green LEDs thatidentify the breaker’s phase to phase voltages being dis-played; i.e.,(VAB), (VBC),(VCA). Values are in volts RMS.1.1.5ZoneInterlockingZone Selective Interlocking(orZone Interlocking)is avail-able(see Fig.2)forDigitripRMS Trip Unitshaving ShortDelay and/orGround Fault protection.Zone SelectiveInterlocking provides thefastest possible tripping forfaults within the breaker’s zoneofprotection,and yet alsoprovides positive coordination among all breakersin thesystem(mains,ties,feeders and downstream breakers)to limit theoutage to theaffectedpartofthesystemonly.When Zone Interlocking isenabled,afault within thebreaker’s zoneofprotectionwill cause theTrip Unitto:•Trip the affected breaker instantaneously,and• Send a signal to upstream RMS Digitrip Trip Units torestrain from tripping immediately. The restrainingsignal causes the upstream breakerstofollow theirset coordination times, so that only the minimum ser-vice is disrupted, while the fault is cleared in theshortest time possible.E:T*NEffective May 1997