Study on FDS characteristics of oil‐immersed paper insulation bushing under non‐uniform moisture content

Abstract

Capacitive high-voltage bushing is one of the typical oil-immersed paper insulation equipment, which is an indispensable external connection component for power transformers. In order to evaluate the effectiveness of frequency domain spectroscopy (FDS) for diagnosing moisture content of oil-immersed paper insulation bushing, this article studied the frequency-domain dielectric characteristics of oil-immersed paper insulation samples and field bushing. At the same time, the basic principle of interfacial polarisation is used to analyse the samples and field bushing with non-uniform moisture content. The results show that the moisture content affects the whole frequency band of the FDS curve. When the distribution of moisture content is non-uniform, the paper with high moisture content has a great influence on the whole FDS curve of oil-immersed paper insulation. In addition, the FDS curves will show a significant loss peak. The frequency of the peak point gradually moves towards the high frequency as the non-uniformity of the moisture content distribution increases. The experimental results show that the variation law of oil-immersed paper insulation can be used to quantitatively evaluate the moisture content and moisture type of oil-paper insulation power equipment.