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.
Birds, substations, and transmission
Birds have the dubious honor of causing more power system outages than any other animal. In addition to directly causing outages by wingtip contacts or nesting activities, they are indirectly responsible for many other animal-caused outages. Not only have birds been a problem since the first power systems were built, but many utilities have had little or no success in devising mitigating measures. Partly, this is due to a tendency to focus on the engineering side of the problem to the exclusion of the "bird" side of the problem. in other words, utilities tend to repair or replace damaged equipment with little or no idea of why the birds were there in the first place or what the probability of a re-occurrence might be. Without an adequate understanding of basic bird behavior, utilities may end up installing deterrents or protective devices that are neither the most effective nor the most appropriate. This paper briefly analyses the type of bird behaviour that causes problems in substations and transmission. The main problems are nesting birds, roosting birds, and large birds. Bird deterrents and equipment protection are also discussed in this paper.