12
MegohmmeterModels6501/6503
CHAPTER 4
OPERATION
4.1 Auto-ranging
How it works:Whenthepointerreachesapproximately90%ofthe
fullscalelength,theauto-rangeistriggered,theredauto-range(x10)
LEDlightsup.Thepointergoesbacktothebeginningofthescale
andresumesitstravel.Thereadingsshouldbemultipliedby10when
thex10LEDison.
4.2 SafetyCheck-VoltageTest
Beforemeasuringinsulationresistance,conrmthatthesampleis
fullydischarged(particularlyindielectricandcapacitancesamples)
andthatthesampleisnotconnectedtoanenergizedcircuit.
Toperformthevoltagetest,settherangeselectiontoVMΩ(Model
6501) or 500V MΩ (Model 6503), connect and read on the red
voltage scale (600V
AC max). DO NOT CRANK. If measuring on
aDCcircuit,thepointerwilldeectbutthemeasurementmaybe
inaccurate.
4.3 InsulationResistanceTesting(MΩRange)
Aftercheckingforalivecircuit(seesafetycheck),selectthetestvolt-
ageandconnectthemegohmmeter.Severalconnectionexamples
areillustratedfurther.CrankthehandleuntiltheAmberLED(Model
6501) or Green LED (Model 6503) on the upper right-hand side
lights,ensuringthattheselectedtestvoltagehasbeenreached.