Corona degradation of the polymer insulator samples under different fog conditions

Abstract

Corona discharges resulting from the metal parts of insulators and the line hardware affect the long term performance of the polymeric insulators used for outdoor application and can lead to its eventual failure. The authors previous work, involved in developing a new methodology to evaluate the performance of polymeric shed materials subjected to corona stresses in the presence of natural fog condition, results revealed more surface hydroxylation thereby resulting in more loss of hydropobhicity. With the increase in industrialization, there is an increase in acidic component of the rain as well as the fog (moisture). The present work, reports the effect of acid fog on the corona performance of the polymeric insulators for both AC and DC excitation, interesting results are obtained. A comparison of the experimental investigations revealed that the acidic fog has more effect than that of the normal fog. This fact has been confirmed by physico-chemical analysis like the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and contact angle measurement. The effect of DC corona is found to be lesser in comparison with the AC; however the hydroxylation induced by the DC corona under the presence of fog is similar with that of AC excitation.Index Terms -acidic fog, Corona, Fourier transform infrared spectroscopy, moisture, silicone rubber, surface oxidation, leakage current.

Electrical Strength and Physicochemical Performances of HTV Silicone Rubber under Salt-Fog Environment with DC Energized

“…It was found that the long-term field exposure yielded weaker insulator deterioration than the salt-fog chamber ageing [15], suggesting that long-term salt-fog aging may have a serious impact on the properties loss of HTV. The salt-fog aging phenomenon under corona treatment is more obvious than that without energy [16]. More hydroxylation induced by corona was found in a cold-fog condition, which may cause a hydrophobicity loss of composite insulators [17].…”

Review of the Performance of High-Voltage Composite Insulators

“…Surface cracks may modify the mechanical and electrical properties of these insulators [ 82 ]. Several researchers have made attempts to understand corona-caused degradation using single and multiple-needle electrode test systems [ 83 , 84 , 85 ]. The purpose of multiple needles is to produce a large area of the degraded surface for different investigations, which is not possible otherwise by using a single-needle electrode arrangement.…”

Influence of load-shedding and night on SiR insulator environmental aging under AC test voltages

“…Corona varying with air-density and humidity is accompanied by UV light, heat, and gaseous by-products (ozone, NO 2 ) and corona discharges leave severe electrical strains and chemical degradation of insulators. Prolong exposure leaves polymer unusable [29]. Heat and light produce surface cracking and erosion [12].…”