Eaton Cutler-Hammer Digitrip RMS 910 Instructions Manual

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

I.L29-889APage204.4ConductingTestsTopreserve theprimaryprotectionfunctionoftheTripUnit,all in-servicetestingwhetherunder‘Trip”or“No-Trip”conditionsisexecutedONLYifloadcurrentval-uesarenogreaterthan50%xlr(lr=theLong Delay Cur-rentSetting). Any attemptto conduct in-servicetestingwhentheloadcurrentexceeds50%of /r,willNOTbeexecutedbytheTrip Unit.Sincethe DigitripRMS910Trip Unitis designedto runwith control powerfrom thePower/Relay Moduleforthedisplaywindowand communications functions, all testingshould be conducted withthe control poweravailable,eitherthroughthePowerRelay Moduleor,whenthebreakerisoutsidetheenclosure,throughthe AuxiliaryPowerModule(APM)(SeeSection1.6and Fig.7).Although the Trip Unitis designedtoperformallofitsProtectionFunctionswithout theexternalcontrol power,andwithoutthedisplayandcommunicationfunctionsavailable,resultsofthe testscouldbeconfusing.Whenperforming asingle-phase primarycurrentinjectiontests,forexample,especiallywhen thesingle-phasecurrentislow,withouttheAPM it may appearasifthe Trip Unitdoesnotrespond untilthecurrentis well-above thesetvalue,leadingthe testertobelievethereisanerrorintheTripUnitwhen thereis none.The reasonthisoccurs isthatthe single-phase test currentisnotagood simulationofthenormalthree-phase circuit.Ifthree-phasecurrenthadbeen flowing,theTripUnit wouldactuallyhave per-formedcorrectly. Usethe APMforcorrectTripUnitperfor-mancewhenever single-phase current injection tests aremade.4.3Testing ProvisionsAs illustratedinFigs.1and9,anintegraltestpanelisprovidedto testtheDigitripRMS910TripUnit.Whilethe IntegralTestPanel doesenableonetochecktheperformanceofmanypartsofthetripsystem,includ-ing:•MicroprocessorFunctions•TripRelease•Trip Settings• LEDs•DisplayPanel•ZoneInterlocking Function•PowerRelayModule•Rating Plug• CommunicationsFunctionsthereare somepartsitcannotcheck,forexample:• Current Sensors•AuxiliaryCurrentTransformers•Bridge Circuits• Calibration Resistors•Potential TransformerModule•AnalogOverride Circuitand thefunctionsofthese elements are best verified byprimarycurrentinjection testing.As indicated in Fig.9,note1,sixdifferent“TestAmps”settings(1,2,3, 6T,8 and10xln)are available fortestingthe phase elementsofthe Trip Unit,andtwosettings (GFandGFT)are providedfortesting thegroundelement. Before startinganytestsequence,checktheUnitStatus (GreenLED)in the lower rightcorneroftheTrip Unit (SeeFigs.1and9)tobe sureitisblinking on and offaboutonce each second,whichindicates that theTripUnitisfunctioning normally.In theevent theUnitStatus LED isnot blinking,install an AuxiliaryPower Module(APM)(See Fig.7), orifyou have already installedone, checktosee thatitis connected correctly.(See Section 1.6.)Ifthe circuit breaker is carrying current,checkthat thecurrentisnotmore than 50%ofthe LongDelay Current Setting(/r);because theTripUnitwillnot executeyourtestinstructions when itsenses that the current through the breakerexceeds the 50%level.Ifthe current throughthe circuit breaker increasesto a value greaterthan 50%of the Long Delay Current Setting, /r,the Trip Unit will automatically abort any TripUnit Test that may be in progress. Should an1)^CAUTIONASETTING OFEITHER6TOR GFTWILL TRIPTHECIRCUIT BREAKER.(SEE SECTIONS4.1AND 4.4.2.)FORANY COMBINATIONOFTHE PHASE PROTEC-TIONSETTINGS, AN APPROPRIATE“NO TRIP”CON-DITION CANBESET TO TEST THE LONG TIME,SHORT TIME AND INSTANTANEOUSTRIPSET-TINGS WITHOUT TRIPPING THE CIRCUIT BREAKER.(SEE SECTION 4.4.1.)IN THE“GF”TEST POSITION,THE LEVEL OF TESTCURRENT, BASED ONln,IS ADEQUATE TO DEMON-STRATE THE OPERATING CONDITION OF THE TRIPUNIT WITHOUT TRIPPING THE CIRCUIT BREAKER.THIS IS A FUNCTIONAL CHECK ONLY, NOTACALI-BRATION.2)EiTN Effective May 1997