| The performance of four high voltage polymer insulators patented in the U.S. by South African researchers was experimentally evaluated using a salt fog chamber. The patent was developed to improve the performance of polymer insulators under contaminated conditions by combining weathersheds of EPDM and SiR on the same insulator. The main purpose of this research project was to verify if these new “hybrid” insulators indeed outperform conventional polymer insulators. Four sets of six types of polymer insulators of identical profiles were evaluated. Each set consisted of four custom-made hybrid EPDM/SiR polymer insulators, one pure SiR insulator, and one pure EPDM insulator.; For this dissertation research an experimental program has been carried out. A total of four case studies that combined the orientation of the insulators (i.e., vertical or horizontal), a new feature suggested for this research for the first time, and the fog salinity level (i.e., low or high) were implemented. In addition, as another original contribution, the distribution of the contamination on the insulator surface (after the aging tests) was analyzed in order to establish a relationship between the salt deposits and the performance of hybrid polymer insulators. A virtual instrument with many new features was implemented using DASYLab to calculate information regarding the leakage current signals. A Fast Fourier Transform (FFT) module was implemented to obtain the harmonic content of the leakage current waveforms during the salt fog tests. The virtual instrument also provided real time display of both the waveform and the frequency spectrum of the leakage current signals. In addition, three methods to determine the phase angle between the energizing voltage and the leakage current were also implemented using DASYLab. The three methods are also new features for a data acquisition system.; The six types of polymer insulators tested were ranked according to a composite score calculated from the average daily increase of their cumulative charge, cumulative pulse count and overall maximum leakage current obtained during each salt fog test. Results also indicate that there is an effect of the orientation on the insulator performance. The use of hybrid polymer insulators by electric utilities is not expected since according to the results obtained during the course of the salt fog tests, they do not display advantages over conventional polymer insulators. |
