Effect of Low Pressure on Insulation Failure of Silicone Rubber for Polymer Insulator

Polymer insulators are being widely used in transmission lines of high-altitude regions. This research was carried out on silicone rubber to investigate the effect of low-pressure on insulation failure. A needle-to-needle electrode system was employed to investigate the insulation failure caused by an arc discharge. The gap distance between the electrodes was made from 5 mm to 15 mm. Obtained results revealed that with reducing the ambient pressure the time to insulation failure increased and both the erosion depth and the weight loss decreased. The weight loss decreased in the narrow gap, but increased in the wide gap; the erosion depth decreased in a wide gap, but increased in a narrow gap; the difference between the gaps decreased with reducing the ambient pressure. It is suggest that the insulation failure of polymer insulator is related with the ambient pressure