Research of aging status assessment of large generator winding insulation by polarization and depolarization current

摘要

To study the influence of aging on time dielectric spectroscopy, the polarization/depolarization current method in time domain dielectric response technique is used for the aging state of generator insulation. Therefore, a multi-factor test is carried out for stator bars and the polarization/depolarization current is tested for stator bars after different aging time. Meanwhile, the influence of different aging time on the dielectric properties of generator insulation is analyzed and the characteristic parameters for aging are presented. The results shows that, the polarization and depolarization current curves move above to the left with the increase of aging time. The depolarization charge quantity is sensitive to the aging state of generator insulation and there is a exponential relationship between the depolarization charge quantity and test time, therefore, the depolarization charge quantity can be used to predict the aging state of generator insulation.