User Manual

Auto‐Ohm200S3/DMOM‐200S3/DMOM‐600USER’SMANUAL REV2
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1.3 DMOM-600 General Description and Features
TheDMOM‐600isspecificallydesignedfortestingEHVcircuit‐breakercontactresistances,
bushingcontactjoints,weldingjoints,orforanylow‐resistancemeasuringapplication.Thishigh
currentandverylightweight(33lbs/15Kg)micro‐ohmmeterisdesignedtomeettheIEEE
C57.09‐1999(5.15)requirementfortestingcircuit
breakercontactresistance.
TheDMOM‐600canaccuratelymeasureresistancevaluesfrom1micro‐ohmto450milliohms.
A0.1micro‐ohmresolutionispossiblewithcurrentgreaterthan10A.TheDMOM‐600appliesa
selectabletrueDCtestcurrentfrom10Ato600Atotheresistanceloadtobe
tested.The
DMOM‐600controlsthetestcurrent’sriseandfallrates.Thetestcurrentriseandfallratecan
beselectedfrom5secondsto10seconds.An“AutoTest”modeisalsoavailableandcanbe
initiatedsimplybyapplyingthesensecables’leadsacrossthetwopointsofinterestinthe
currentpath.Thisfeatureisveryconvenientwhenmeasuringasequenceofseveralresistance
valuesinacircuitbreakercontact.TheDMOM‐600canalsocomparetestresultsagainstpreset
limitsanddetermineifatestpassedorfailed,anda“Pass”or“Fail”flagisdisplayed
accordingly.
SinceatrueDCcurrent(withcontrolledrise/falltime)ispassedthroughthecircuitbreaker
contact,nomagnetictransientisinducedintothebreaker’scurrenttransformers.Thisfeature
greatlyreducestheriskofinductivelytrippingabreakercontrol(busdifferentialrelay).
WiththeDualGroundoption,theDMOM‐600canalsomeasurethecircuitbreakercontact
resistancewithbothsidesofthebreakerbushingbeinggrounded.Whenatestcurrentis
appliedtoacircuitbreakerwithbothsidesgrounded,someofthetestcurrentflowsthrough
thesafetygroundcables.Usinganexternalcurrentsensor,theDMOM‐600measuresand
eliminatesthiscurrentfromthetotaltestcurrent.Itthencalculatestheactualresistancevalue
ofthecircuitbreaker.
TheDMOM‐600featuresaback‐lit128x64pixelLCDscreenthatisviewableinbothdirect
sunlightandlowlightlevels.TheresistancereadingsaredisplayedinalargefontontheLCD
screeninmicro‐ohmsormilliohms.Theunitisoperatedviaaconvenient44‐key“QWERTY”
keypadonthefrontpanel.TheDMOM‐600canstore128recordsof64readingsinternally,and
up999testrecordsonanexternalUSBFlashdrive.Testheaderinformation(Company,
Substation,circuitbreakerID’s)canalsobeenteredusingthe44‐keykeypadandisstoredwith
eachtestrecord.TheDMOM‐600alsofeaturesabuilt‐in2.5”widethermalprinterthatcanbe
usedtoprinttestreportsinthefield.
Windows®based(XP/Vista/7)analysissoftwareisprovidedwitheachunitandcanbeusedto
remotelycontroltheDMOM‐600viatheRS‐232Cport.Usingthissoftware,theusercan
retrievetestrecords(fromtheunit’smemoryoraUSBFlashdrive),analyzetestresults,and
printtestresultsonadesktopprinter.Testresults
canalsobeexportedtoPDF,Excel,andXML
formats.
TheDMOM‐600isfurnishedwitha15‐ft(#1/0AWG)testcableset.Customtestcablelengths
areoptionallyavailable.Optionalheavy‐duty,weldingtypeC‐clampsarealsoavailableallowing
theusertoconnectthetestleadstoawidevarietyofbushingsizes,bus‐bars,orlarge
conductors.