Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Patent
1998-05-18
2000-08-22
Leja, Ronald W.
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
174144, H02H 100
Patent
active
061081876
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The proposed invention can be related to the field of high-voltage techniques, more precisely for electric power transmission lines with protection devices against overvoltages during a thunderstorm, including those in a form of impulse lightning arresters.
PRIOR ART
The known high-voltage power transmission lines comprise, as a rule, a power conductor fastened on structures by means of insulators, and lightning protection facilities, i.e. devices for limitation of overvoltages, occurring when lightning strikes the line. The line can include several power conductors, if, for example, it is a multiphase one. As a rule, structures are grounded, but there could be also some ungrounded designs. Usually a power conductor is connected with a supply cable via a cable termination.
The most commonly used electric power transmission lines include arc horn arresters as devices limiting overvoltages, that are made in the form of two metal rods located directly close to insulators, or strings of insulators, or other protected line elements. The said metal rods are placed at some distance one from another, creating a spark gap, and when an overvoltage occurs as a result of lightning striking an electric power transmission line, the said discharge goes through the said spark gap of the arrester, thus protecting the insulator from destruction.
There is another well-known type of electric power transmission line with a facility for overvoltage limitation, made as a rectifying arrester, consisting of one or several (depending on the voltage class) standard elements, connected sequentially. Each of the said elements comprises discs of nonlinear resistors with spark gaps between them, wherein each of the spark gap and nonlinear resistors sets are placed within a porcelain hermetically sealed cover (cf. High voltage techniques. Ed. D. V. Razevig, M., Energiya, 1976, p. 300).
Lines with such arresters are reliable, but the rectifying arresters included therein are complicated and expensive, increasing costs for their usage and construction of the whole line.
Another known electric power transmission line with a facility for overvoltage limitation, made as a tube arrester, consists of a vyniplastic tube, blind with a metal cover, that is one of the end electrodes. On the said cover an inner rod electrode is fixed. The free electrode and the end one, fixed at the free end of the tube are the main electrodes. In such a line, the arrester tube is separated from the power conductor by an external spark gap (cf. High voltage techniques. Ed. D. V. Razevig, M., Energiya, 1976, p. 289).
This known line has a drawback of protection unreliability, for its arrester operation is accompanied with the release of highly ionized allied gas, and this can initiate flashover of air insulation in the case of adjacent phase conductors and grounded constructions ingress into a zone of arrester exhaust. The known design arrester has a limited range of interrupted currents and is short-lived because the vyniplastic tubes burn out when discharge current flows through them.
There is also a high-voltage support insulator type which consists of an insulation body (in particular, fabricated of ceramics) having sheds as well as metal flanges at the ends thereof serving for fixation of the insulator to the support structure (cf. High voltage techniques. Ed. D. V. Razevig, M., Energiya, 1976, p. 78).
There is yet another support ceramic insulator which comprises an insulating ceramic body with spiral sheds and metal flanges, placed at the ends of it (cf. High voltage technics. Ed. D. V. Razevig, M., Energiya, 1976, p. 85).
The known insulators in lightning overvoltage circumstances have an air gap between the metal flanges flashovered, and then the said gap, under effect of the operational frequency voltage applied to the power conductor turns into a power arc of the line, which requires the emergency cut-off of a high-voltage line containing the mentioned insulator.
There is a fitting known for insulator fastening to structure having fo
Podporkin Georgy Viktorovich
Sivaev Alexandr Dmitrievich
Leja Ronald W.
Streamer Electric Company, Inc.
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