Accelerated electrical degradation of machine winding insulation

Modern electrical machines must be designed as rugged and flexible. The use of power electronic devices causes voltage spikes and introduces harmonics that electrically degrade the insulation of the windings in the machines. Power electronic driver circuits operate at high frequency, resulting in high electrical stress and temperatures, which affect the aging and breakdown properties of the machine winding insulation. High frequency pulse voltages can be used to study the impact of electrical degradation of the machine winding insulation that exists in electrical machines. Insulation materials were tested at 90% rated temperature for the materials. Evaluation of the change in dielectric strength was monitored versus the aging caused by the high frequency pulse voltage. In many high voltage systems, breakdown voltage is an indication of insulation condition. Partial discharge presents issues of electromagnetic compatibility as noise source. Therefore, breakdown test and partial discharge inception/extinction voltage test at 60 Hz was performed on the twisted wire samples. The possible increase in surface conductivity due to ionization, and partial discharge activity was simulated.