A comparative study on the effect of acids on the hydrophobicity of HTV and LSR polymeric insulators

Overhead transmission lines insulators which located near chemical factories are suffering from industrial pollution that characterized by industrial waste gases produced from the chimneys of these factories. In fact, the substance such as SO₂ in air is increasing continuously due to the influence of industrial waste gas, and it will form acid rain or acid fog. The surface conductivity of polluted insulators will increase greatly and reduce the insulation characteristics of them under acid rain or fog conditions. Unfortunately, there is a lack of test results about the electrical and physical performance of polluted composite insulators under acid rain or fog. The effect of acids on silicone rubber insulators (either on high-temperature vulcanized silicone rubber (HTV) or liquid silicone rubber (LSR) samples) is thoroughly investigated in this paper. Several specimens were individually immersed in sulphuric acid with different concentrations of these acids in the air for a suitable time. Every 6 hours one specimen is taken off from the solution and then it was investigated by measuring the contact and/or receding angles. The specimens were left to be dried and the contact and/or receding angles were measured to study the recovery phenomena of both HTV and LSR insulators.