Modern Methods of Continuous Insulation Measurement

Abstract

In the chapter modern methods of insulation continuous measurement are presented. The simplest one is imposition of an auxiliary AC test signal between DC network and ground. Procedures based on connection of a resistor between ground and one or both DC network poles are simple methods of indirect (i.e. based on measurement and calculation) determination of insulation-to-ground resistances. This solution is also referred to as “commutation method”. Waveforms of a chosen pole-to-ground voltage recorded during commutation are shown. “Pulse” (rectangular) test voltage imposition is another commonly applied approach. Details of the method are explained and formulas necessary for insulation-to-ground equivalent resistance determination are derived. Few examples of these methods implementation are presented and waveforms illustrating the devices operation are attached. Three other unconventional concepts of insulation continuous monitoring are described. These ideas include insulation leakage resistance automatic control, insulation ground capacitance compensation for an auxiliary AC test signal as well as imposition of auxiliary voltage “triangle” pulses.