Study on leakage current characteristics and influence factors of 110kV polluted composite insulators

In this paper, the artificial contamination test of composite insulator(FXBW-110/100) was carried out in the artificial climate chamber. The leakage current signal of composite insulator with different contamination and hydrophobic state was collected. Through the analysis of the leakage current of the time and frequency domain, its characteristic parameter characterization method of leakage current based on the pulse amplitude(Ih), energy ratio(K) and energy(E) of leakage current is proposed. The results show that under the same voltage, the leakage current pulse amplitude increases with the increase of salt deposited density (SDD) of composite insulators. With the increasing of SDD, there are more frequent the surface discharge occurred and more spike pulses in the leakage current waveform. In the same pollution state, with the decline of the hydrophobicity(HC) grade of composite insulators, the amplitude of the leakage current increases gradually and the frequency of the pulse increases gradually. Through the Fast Fourier Transformation(FFT) analysis of the leakage current, it is found that the highest leakage current is the basic wave, the three and the five harmonic. With the increasing of SDD and hydrophobicity, all of the leakage current harmonics were increased to a certain extent, however, the increasing amplitude of three times and five times harmonic were bigger than that of fundamental wave. The three characteristic parameters of leakage current, i.e. pulse amplitude (7h), energy ratio(K) and energy (E) all increase with the increase of SDD, and the decrease of HC.