Experimental study of the possibility of detecting contamination of high-voltage insulators with the help of a thermal imager

ACTUALITY. External insulation is one of the most damaged elements of high-voltage equipment. Changes in climate, ecology have an increasing impact on it’s condition. The proportion of overhead transmission line (OTL) outages due to pollution varies by region and specific operating conditions, but on average it can range from 20% to 40% of all OTL failures. In regions with high levels of industrial pollution or near sea coasts, this figure can reach 50% or more. The main causes of outages are related to the accumulation of contaminants on insulators, which leads to overtopping in wet conditions. It is precipitation such as drizzle, fog or dew that has the greatest impact, combined with various solid conductive particles deposited on the insulator surface from the air, and forming a layer of surface contamination. Methods for diagnosing insulation are various, including thermal imaging. OBJECT. To study the effect of wetted contaminated surface of glass and polymer insulators on their temperature under laboratory conditions and to evaluate the possibility of diagnosing the contaminated condition. METHODS. Three dozen laboratory experiments with suspended glass and polymer insulators in a fog chamber with thermograms, control of leakage current and degree of contamination were carried out to achieve the goal. During the experiments, the degree and method of contamination and humidification conditions were changed. RESULTS. In the course of laboratory studies it was shown that thermal imaging cameras can diagnose even lightly contaminated insulation in the wetted state. The mean and rms values of temperature contrasts depend more on the level of contamination (greasiness) than on the degree of uniformity of contamination application. The methodology of construction of the insulation control system on overhead power lines and the algorithm of automated data processing are proposed.

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