Accelerated aging tests on magnet wires under high frequency pulsating voltage and high temperature

Breakdown voltage and accelerated multistress aging tests were conducted on fine gauge magnet wire of heavy build insulation film of polyurethane resin with nylon overcoat. The aging tests were carried out under simultaneous high frequency pulsating voltages (15-40 kHz) and high temperatures (100-180°C). The effects of the duty cycle and rise time of the voltage pulse on the time-to-breakdown were also investigated. The experimental results show that the insulation aging is mainly caused by increasing the applied voltage magnitude and temperature. Increasing the frequency, however, is not the major factor in insulation deterioration. The results also show that fast rising voltage pulse and long duty cycles severely shorten the lifetime of the insulation