AEMC 5050 - Page 15

Megohmmeter Models 5050/5060 13
Thetestvoltageischoseninthesamewayastheinsulationmeasurementinthe
SET-UPmenu.Thedevicethencausesafastdischargeduringwhichtheinsula-
tioncapacity ismeasured, thenmeasured 1minute afterthe residualcurrent is
circulatingintheinsulation.
TheDDvalueiscalculatedfromtheformulabelow:
DD=
 currentmeasuredafter1minute(mA)
  testvoltage(V)xcapacitymeasured(F)
Theindicationof theinsulation qualityasa functionoftheresultingvalue isas
follows:
DD value Insulation quality
DD >7 Very bad
7 >DD >4 Bad
4 >DD >2 Doubtful
DD <2 Good insulation
NOTE: The dielectric discharge test is suited for the insulation measurement of
rotating machines, and in general, for the insulation measurement of heteroge-
neous or multilayer insulation containing organic materials.
Using the R-DAR-PI-DD Function:
Duringoraftermeasurement,theR-DAR-PI-DD buttonallowsyoutoscrollthrough
thefollowingvalues:
• DAR(formeasurementslasting>1min)
• PI(formeasurementslasting>theprogrammedPItimes)
• DDcanonlybecalculated1minuteaftertheendoftheinsulationmea-
surementandcircuitdischarge,andonlyifitwasselectedbeforebegin-
ningthemeasurement.
• CapacitanceinµF(onlyafterthemeasurementhasstoppedandthecir-
cuithasbeendischarged)
• ResidualleakagecurrentcirculatingintheinstallationinµAornA
• InsulationresistanceinMΩ,GΩ or TΩ
NOTE: During the measurement, the DAR value is not available if the DD value
was preselected before the measurement. The PI value is not available if DAR or
DD values were preselected before the measurement.
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