Electrical aging of inverter-fed wire-wound induction motors: from quality control to end of life

In this paper, the IEC 60034-18-41 technical standard procedures for assessing the quality of Type I (random wound) motors through (offline) partial discharge testing are briefly summarized first. After, offline and online measurements performed on one motor, able to pass the tests but failed soon after energization through a PWM inverter, will be compared. The analysis will highlight the pros and cons of the standard.