A comparative study on leakage current harmonics of porcelain disc insulator contaminated with NaCl and KCl

Flashover on disc insulator of over head transmission line is a major problem in power industry. Due to deposition of different contaminants particles, the surface of the disc insulator deteriorates which results in flashover occur on it. Hence, condition of the insulator surface must be monitored on regular basis in order to avoid the failure of power transmission. For this purpose, different approaches are taken to assess the condition of the insulator surface among which measurement of surface leakage current is found to be most efficient. But, existing literature shows that determination of peak value of leakage current is not always a good indicator to investigate the condition of insulator surface. Considering the above-mentioned fact, a different approach has been taken here that can efficiently predict the condition of insulator surface. Instead of determining the peak value, the harmonic contents present in the leakage currents has been evaluated to study the condition of insulator more accurately. For this purpose, an experimental setup has been developed in the laboratory that can measure the surface leakage current at different applied voltage. A disc insulator is contaminated separately with KCl and NaCl mixed with kaolin. The surface leakage current of the contaminated disc insulator is measured at different voltage and salinity level. Harmonic content present in the surface leakage current is evaluated for KCl and NaCl contamination at different voltage and salinity level. It may be observed that the harmonic contents present in leakage current are good indicator of salinity level.