Study on ageing properties of magnet wires' insulation used for electric locomotive pulling motors

The pulling motor of electric locomotive is controlled by pulsed width modulated (PWM) adjustable speed drives. Under conditions of PWM, the insulation function of the electromagnetic wire declines very fast because of the influence of ageing at high frequency and high temperature. By contrast with conditions of the power frequency, the damage level of the electromagnetic wire in the environment of electrical and thermal ageing is apparent. In this paper, the comprehensive insulation test is carried out in order to study the influence of ageing in the insulation of the electromagnetic wire in the power frequency. In the process of ageing test, the insulation characteristics are analyzed with partial discharge tests. With the digital data processing, the curves of the trend of testing parameters and failure time are obtained. According to analysis the statistic parameters, the ageing mechanism of the electromagnetic wire is analyzed in the power frequency.