Indeed, most outages with no apparent cause are usually attributed to birds. Bird excretions (better known by the euphemism ‘streamers’) sometimes launch massive volumes of conductive material directly onto insulator surfaces or across air gaps, often triggering flashover in an instant. If pecking silicone insulators was not enough to make power engineers want to hurl stones in the direction of large birds, an even more widespread ornithological threat is demonstrated by this image. An insulator with the excellent hydrophobic behavior shown in this image (Class 1) should provide peace of mind to engineers, with its implied assurance that no matter what the pollution and wetting situation, it will resist formation of conductive paths and excessive leakage current. However, this has changed dramatically as silicone vaulted from relative obscurity in the T&D field to becoming a mainstay of HV line and substation insulation, comparable to porcelain or glass. ![]() It may seem strange these days, but in the early 1990s few power engineers had ever heard of or cared much about that tongue twister term, ‘hydrophobicity’. Fortunately, no one was nearby at the time since sharp pieces of porcelain were later found embedded in structures many meters away. Explosive failures have occurred in many countries, such as this one at a substation in Crete a few years ago that caused over million Euros of collateral damage and was reported on in INMR shortly after it occurred. The catastrophic failure of any porcelain-housed component (such as the transformer bushing shown in this image) can lead to ejection of lethal shards at velocities that make them a threat not only to people but also to other assets across a large radius. But none seems to have yet become industry standard. A number of techniques have been proposed to shield composite insulators from severe bird-pecking damage during the period between installation and energization, when this problem apparently lessens due to high electric fields that keep birds away. The problem has been so severe in certain areas that large numbers of insulators on new lines were found critically damaged even before energization. Australia is home to many species of exotic birds that sometimes find insulators a convenient place to sharpen and exercise powerful beaks. This one image has made composite insulator manufacturers around the globe shudder since it reveals in an instant one of the ‘Achilles heels’ of this otherwise brilliant technology. However, notwithstanding their menacing appearance, these growths do not present any longterm danger of degrading the silicone housing material. Research over the years by Professor Stanislaw Gubanski and colleagues, demonstrated that such growths should ideally be removed by water washing followed by alcohol since they create localized sites of moisture accumulation. A similar problem – although more severe – was reported in the mid 1990s on 230 kV composite breaker bushings by a rural power utility in Florida. The rainy and damp environment in the region soon resulted in appearance of substantial biological growths on the shaded lower portion of sheds. This was also the site of one of the first installations of composite-housed bushings, mounted in different configurations during the 1980s. A nighttime inspection of the main line that supplied the facility resulted in this remarkable photo that reveals partial flashovers in progress along the porcelain long rods.Īnneberg was the name of a now-closed insulator research station located in southern-eastern Sweden and operated for years by Chalmers University of Technology. A large chemical works near the Dead Sea in Israel suffered from frequent outages, due in large part to a severe local pollution environment of alkali salts. ![]() When customers complain of unreliable electricity supply, it’s rare to be able to capture the essence of the problem with a single snapshot. Here some of our most interesting images covering 26 years of visits to power network across the globe. But being on the spot to capture an event that links directly with the topic of a particular article – that requires planning and dedication but mostly luck. Of course, taking photos of an overhead line or substation is one thing. There’s a well-known proverb: “a picture is worth a 1000 words” and INMR has always set itself apart from other journals in the T&D field in terms of the number and variety of unique photos offered to readers.
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