DO6Handbook
Jan2006 4of 107 pages
1. Introduction
1.1Use
Fastandaccuratemeasurementsofultra-smallresistancescanbemadeusing theDO6
milliohmmeter. Withitsruggedtable-topcaseandmembranekeypad, thisinstrumentis
designedforbothlaboratoryuseandharshindustrialenvironments.
Temperature-compensatedresistance-testingofwiresandcoilsispossibleusing aPt100
sensororpyrometertomeasurehetemperatureofthedevice undertest.Heinstrumentthen
corrects theresistance toe.g. 20°C(selectable)
Themeterhasahugerangeofapplications, suchasmeasuring:
•Transformer/motorwindings
•Coilsofanykind
•Cablesandwiresonthedrumorasmetersamples
•Switchandrelaycontacts
•Heatingelements
•Connectionsandcontacts topowerrails, and
•muchmore
CompletecontrolcapabilityviatheRS232 PCinterface meansthatfullyautomatictest
stationscanbesetup.ThemeterincludesaPLCinterface forintegrationinproduction
process controllers. A2-waycomparatorwithPLCandrelayswitching outputsisalso
providedforclassificationandselectionofthedevicesundertest.
1.2Description
Themeterworks onthebasisoftheproven4-wiremeasurementmethod, inwhichtest-lead
resistancesandcontactresistancesareeliminated. Themeasurementtechniquealso
compensatesautomaticallyforanythermalEMF’s inthemeasurementcircuit. The
instrumentleadsaremonitoredfordamagebyabuilt-indetector.
Ofcoursethemeterincludestemperaturecompensationforanytypeofmaterialundertest
suchascopper,aluminium,brass, tungstenetc. usinganexternalPt100 sensororexternal
infraredthermometer(accessory)tomeasurethetemperature.Aspecialcircuitforprotecting
themeasurementinputwhenmeasuring high-inductivedeviceshasbeendevelopedtoprevent
damagetothemeterfromvoltagepeaksproducedwhendisconnectingthedevice undertest.
Ifthereisarequirementtotestdevicesusing differentparametersinanautomatictestsetup,
thenup to16 device settingssuchasmeasuring range,limits, temperaturecoefficientetc. can
besaved. Alldevice-specificsettingsareshownonthedisplay.
ThesettingscanberetrievedviathekeyboardorPLCinterface using abitpattern(4bits).Of
coursealldevice settingscanalsobemadeviatheRS232 interface.
Abacklit, highcontrastLCDdisplayisusedfordisplaying thereadings, soitisextremely
easytoreadthemeasurementinbothdarkandwelllitrooms.
