Wet tests on naturally polluted glass and composite insulators
The study examines what type of bird excrement contamination will lead to insulator's flashovers on the Estonian 110 kV overhead power lines. Wet tests made in laboratory with naturally contaminated glass and composite insulators show that traditional (insulator's surface) contamination will not lead to flashovers and therefore most likely the flashovers are caused by highly conductive bird excrement streamers. The tests also show that using corona rings at composite insulator's line end fittings, affects the occurring probability of partial discharge extent on wetted insulator.
Effect of arc current on properties of composite insulators for overhead lines
Results of power are tests carried out on composite insulators for 110 kV overhead lines are analyzed. The effect of arcing on the basic electrical and mechanical parameters of the tested insulators is examined. Results of pre- and post-arc electric strength tests as well as those of thermomechanical and mechanical tests carried out on insulators subjected to the power arc test are presented.
Bird Streamer Initiated Breakdown Characteristics under HVDC Conditions
A study of the role played by bird streamers (bird excretements) in transmission line faults under HVDC conditions is described in this paper. The research was initiated due to the lack of knowledge regarding this phenomenon. An insight is given as to what bird streamers faults are, and their role in the breakdown of air-gaps. A model HVDC transmission line tower has been built at the HVDC laboratory at the University of KwaZulu-Natal. The tower was used facilitate in the air-gap breakdown tests. The tests were carried out in order to find the minimum distance required on a transmission tower top for a flashover to occur. The results obtained show that a streamer effectively reduces the air-gap between the tower and the live fitting on a tower. An indication of future work will be given.