HARMONIC ANALYSIS OF LEAKAGE CURRENT OF SILICON RUBBER INSULATORS IN CLEAN-FOG AND SALT-FOG

International audienceEnvironmental and electrical stresses have deterioration effects on Silicon Rubber (SIR) insulators. In coastal areas due to high amount of salt, humidity and dust suspended in the air, the deterioration process is intensive. In this paper, based on IEC 60507 the leakage current (LC) of 20kV SIR insulators has been investigated in clean-fog and salt-fog with and without artificial pollution. Tests have been executed with six similar SIR insulators. A pair of polluted and clean SIR insulators is subjected to clean-fog; other two pairs are subjected to salt-fog with 5 and 10 kg/m 3 salinity respectively. Results show that combination of pollution and salt-fog is more destructive than clean-fog, where the main reason may be the increase of conductivity. Dry band arcing makes insulator perform nonlinearly and some LC waveform harmonic growth. The Fast Fourier Transform (FFT) method, used to find the harmonic spectrum of the LC. Results, also illustrate the coordination between the 3 rd and 5 th harmonic components of the LC and insulators surface condition