Automatic system for detection critical conditions in overhead lines distribution insulators based on leakage current analysis

In this paper, a new automatic system has been proposed for critical conditions diagnosis of distribution insulators. In this regard, a variety of experiments have been conducted on different types of insulators under different environmental conditions. Leakage current harmonics on these experiments have been analyzed. Fast Fourier Transform (FFT) applied on leakage current waveforms and results show a strong correlation between third to fifth harmonics amplitude ratio regarding to insulators conditions. Therefore, third to fifth harmonics ratio of leakage current (R3/5) has been proposed as an indicator to diagnosis critical conditions in distribution insulators. Results demonstrate if value of index R3/5 becomes more than unit, it will be critical condition for insulator and high probability of flashover occurrence. Hence, an automatic system designed for critical conditions detection and flashover prediction using the index R3/5.