Using of the Aging Models and Rotating Machine Insulation Evaluation

The voltage waveforms generated by power frequency converters affect significantly the reliability of drive wall insulation. A power inverter produces modulated voltage on its output which contains square-shaped voltage impulses with fast rise times. This allows controlling the drive speed and torque, but in the same time it has significant effect on the wall insulation reliability. This type of voltage rapidly ages the insulation system. This leads to the breakdown of insulation which means the drive failure. The problem is to predict the machine wall insulation lifetime, when it operates as a part of the power inverter fed drive. The main goal of the research project was to provide quantification of the wall insulation reliability decrease. Insulation systems were laboratory aged both, by the ac 50 Hz voltage and high frequency pulse voltage (slew rate 16 kV/mus). The life time curves have been evaluated and simple mathematical models have been employed to show the wall insulation reliability decrease. The results will be used in a new more accurate aging models designing.