Condition monitoring of stator windings in induction motors. I. Experimental investigation of the effective negative-sequence impedance detector

The former US Bureau of Mines funded a research project aimed at developing the enabling technology for incipient failure prediction in electric power system components as a means of reducing the injuries and fatalities that sometimes occur when equipment malfunctions. Over the ensuing years, interest in this has waxed and waned, but interest has been growing for both civilian and military applications. This paper addresses the level of turn-to-turn insulation deterioration that can be resolved using an online monitoring technique based upon an effective negative-sequence impedance detector. The detection of turn-to-turn defects is especially important because they are believed to represent the beginning stage of most motor winding failures.