Insulator Leakage Distance Dimensioning in Areas of Winter Contamination using Cold-fog Test Results

Abstract

Electrical utilities have adapted insulator leakage distances to a wide range of contamination environments. This has led to development of guidelines for unified specific creepage distance, for example in IEC 60815. Under freezing conditions, a number of factors change. The surface conductivity of ice is much lower than that of water, but there is the countervailing possibility of accumulating a significant amount of ice. One of the crossover points between applications occurs when a very light layer of hoar frost or freezing fog, simulated in a "cold fog" test, fully wets a precontaminated insulator. The leakage distance requirements for these conditions are compared with those suggested for conventional clean-fog requirements. The possibility of treating fog accretion as a form of non-soluble deposit density is explored.

Effects of electric field distribution on icing and flashover performance of 220 kV composite insulators

“…Such effect makes ice structure dense and its density increase. When testing voltage is low, electric field of insulators without grading ring still has the effect of attraction on polarized droplets and ice density increases [20][21][22][23][24][25]. When testing voltage is high, corona occurs on the low voltage end, and ice density decreases.…”

“…When testing voltage is low, the former effect plays a major role, which increases ice weight. Otherwise, the latter effect plays a major role, which decreases ice weight [1,[21][22][23][24][25][26][27]. Take FXBW-220/110 for example.…”

“…Actually, if ice density is small and bubbles become more, ice is easy to melt and break by the partial arc, which leads to bridging is difficult to maintain. Flashover voltage will increase [4,8,[20][21][22][23][24][25][26][27][28]. In light of 3.1 (2), icicles on the sheds always bend towards core rod, which increases the effective leakage path and increases flashover voltage.…”

Studying AC Flashover Performance of Suspension Insulators Under Natural Cold Fog and Wet Deposition Conditions

“…Conducting experiments on flashovers in cold fog to study the characteristics of the insulator in such conditions is thus important. No specialized method for this is available in China, whereas long-term studies have been carried out across the world on the flashover characteristics of the insulator in cold and foggy conditions by using artificial climate chambers [5], [14], [18], [19]. Cold fog flashover is common in China, but has been classified as pollution flashover even though its process of development and characteristics are significantly different [20].…”

Discrete Wavelet Transform analysis under non uniform contaminated conditions for pollution severity estimating

“…For this reason, their efforts are especially based on designing and dimensioning insulators with excellent dielectric performance in severe pollution conditions [1,2]. Most of the time, the formation of polluted layer can be caused by natural or anthropogenic parameters [3].…”