Using polarization/depolarization current characteristics to estimate oil paper insulation aging condition of the transformer

The polarization/depolarization current method is an aging evaluation method of oil paper insulation. It is non-destructive and without need to handle the transformer. In this paper, characteristic of time domain dielectric response method was studied which based on the polarization/depolarization current method. The experimental platform was built in the laboratory, and the time domain electric conduction model based on time domain dielectric response was established. In different aging time, the polarization/depolarization current of oil paper insulation products was tested. Through the relationship between polarization/depolarization current and dielectric response, polarization conductivity was calculated. It proved that polarization conductivity increases with the aging time. In this paper, the least square method was used to fit the polarization conductivity and aging time. The results showed that the characteristics and the aging days of oil paper have exponential relationship. This provides a new method for quantitative evaluation of transformer insulation aging characteristics.