Pulse Voltage and its Aging Effect on PD Characteristics of Slot Insulation

Usage of the modern power electric drives brought advantages in induction motor control. In the same time problems with "pulse stress" produced by the voltage converters appeared. The converters produce repetitive pulses with the high level of voltage rise fronts (slew rates). Rise fronts attained values of up to tens kilovolts per microsecond and voltage pulse repetition frequency up to some tens of kilohertz. However, this technology is an advantage for a drive control; the voltage waveforms generated by power frequency converters may affect significantly the reliability of the electric motor insulation systems. This study is presenting observation of the aging by the high frequency square waveform voltage of frequently used slot insulation. For the studying slot insulation aging process under pulse voltage were chosen partial discharge parameters: the partial discharge inception voltage (PDIV), partial discharge activity level and partial discharge phase resolved characteristics.