DC Insulation Resistance (IR) and Polarization Index (PI)
A megohmmeter (insulation resistance tester), is used to measure the ohmic value of an insulator under a direct voltage of great stability.To measure a high value resistance, techniques for measuring a low value current are used. A constant voltage source is applied to the resistance to be measured and the resulting current is read on a highly sensitive ammeter circuit which displays the resistance value. Insulation resistance test is a non-destructive test and can detect if insulation is good.
Application includes: Transformers, Current and Voltage Transformers, Bushings, Generators, Motors, Switchgear
