Insulator Leakage Current Measurement is important to inspect the insulator silicone rubber coatings performance, can be done in AC high voltage of 50Hz.
Leakage Current Measurement
An AC high voltage of 50 Hz was applied to the insulators. The applied voltage was adjusted to get various conditions such as normal condition, small or high activity of dry band arcing.
The leakage current flowed on the insulator surface was measured by measuring the voltage across a series resistance using a Digital Oscilloscope TDS series with digitizer of 8 bit, bandwidth of 100 MHz, and the maximum sampling rate of 1 Gs/s.
LC waveforms including low and high frequency components were obtained. The digital data was transferred to a personal computer through a GPIB for further analysis. The leakage current waveform is usually a distorted-sinusoidal [4]. The harmonics content determines the degree of distortion from the sinusoidal. In this experiment, the LC waveforms were measured using a computer-aided measurement system and the harmonic content was analysed.
Fourier transformation is used to analyse the harmonic content of the leakage current. In this case we used FFT (Fast Fourier Transform) which can be obtained in MATLAB to analyse the leakage current harmonic. For the quantification of the harmonic content of the leakage current we used the THD (total harmonic distortion).
Hydrophobicity and Surface Smoothness
Hydrophobicity of RTV silicone rubber coated insulator surface is indicated by its contact angle. The contact angle was taken using Sony digital camera with macro lens.
Insulator surface smoothness also been investigated. It is analysed if there is any dependency between the smoothness of insulator surface and hydrophobicity of insulator surface