PD activity inside random wire wound motor stator insulation and early failures: A case study analysis

This paper presents the outcome of a partial discharge test campaign performed on random wire wound stator insulation of electrical motors. The test campaign was carried out in the frame of a rewinding program involving some units that experienced early failures due to insulation breakdown. The cause of the early failures was targeted to the pollution of the motors due to the harsh environment. Besides the performance of the stator insulation was investigated in many conditions in order to check its compliance with the operating conditions and with the technical standard requirements.