Electricity: conductors and insulators – Electric shock hazard protective devices – Shock protection – grounding devices
Reexamination Certificate
1999-02-11
2001-05-29
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Electric shock hazard protective devices
Shock protection, grounding devices
CD13S184000
Reexamination Certificate
active
06239357
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to insulating covers and, more particularly, to insulating covers for overhead power transmission lines.
BACKGROUND OF THE INVENTION
Electrical power may be transmitted from a generation source to consumers via overhead conductors strung between towers or poles. Electrical power is typically transmitted in phases wherein multiple conductors are utilized. One or more of these conductors are “hot” conductors carrying a specified amount of alternating current electric power and one conductor serves as a ground. Flashover may result if contact is made between hot conductors or between hot conductors and other grounded objects. Non-grounded contact with a hot conductor, such as when a bird sits upon a hot conductor, typically does not result in flashover.
Because uninsulated conductors are typically less expensive than insulated conductors, many electric power suppliers utilize uninsulated conductors for power transmission. With often hundreds of miles of transmission power lines, the use of uninsulated conductors can result in large cost savings to electric power suppliers. Uninsulated conductors are typically strung between towers or poles such that there is sufficient clearance between the conductors to avoid contact therebetween or with grounded objects.
Although bare conductors may be less expensive to install than insulated conductors, potentially costly problems may arise as a result of their use. Adequate clearances between conductors and/or other grounded objects may not be sustainable during adverse weather conditions (i.e., storms and high winds). As a result, the potential for flashover caused by conductors contacting one another or another object may be increased. Another source of flashover may be caused by large birds and animals which have sufficient size to make contact with a hot conductor and a grounded object or other conductor. In addition, falling trees and tree branches may cause contact between hot conductors and ground, resulting in flashover.
Flashover may result in a power outage which is undesirable to electric power suppliers and to consumers. For existing power transmission systems, electric power suppliers may find it desirable to replace bare conductors with insulated ones in order to eliminate the chance of flashover. Unfortunately, the cost of replacing bare conductors with insulated conductors may be expensive. Furthermore, an interruption in the delivery of power may be required to replace the conductors. This may be economically disadvantageous to an electric power supplier as well as being undesirable to electric power consumers.
Insulating covers for temporary use in protecting workers from live power lines are available. Unfortunately, these insulating covers are typically designed for short term and/or local use. Furthermore, existing covers, such as Applicant's OLIC (Overhead Line Insulating Cover) product line, are typically available only in short lengths, typically ten feet (three meters) and less. Because of their shape and configuration, these temporary covers may be bulky and somewhat difficult to handle in longer lengths. A power line span between supporting towers or poles may exceed hundreds of meters. As a result, many of these temporary covers may be required to cover an entire span. Unfortunately, gaps between adjacent covers would be potential sources of flashover.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide covers capable of protecting overhead power transmission lines from flashover caused by contact with a grounded object or another conductor.
It is another object of the present invention to provide flashover protection covers that can be installed on existing power transmission lines without requiring a power outage during installation.
It is yet another object of the present invention to supply flashover protection covers in a continuous configuration so as to cover an entire power transmission line span between supporting structures.
These and other objects are provided, according to one aspect of the present invention, by flashover protection covers provided in continuous lengths that can enclose a live electrical power line within a chamber contained within another chamber. A flexible panel has an inner surface and generally parallel opposite edge portions configured to be joined together to form a first longitudinally extending chamber. A longitudinally extending first wall has an arcuate shape connected along an edge portion thereof to the inner surface of the panel. The first wall also has an opposite free edge portion. The first wall is configured to form a second longitudinally extending chamber within the first chamber. The second longitudinally extending chamber is configured to enclose a power line when the panel edge portions are joined together. The free edge portion of the first wall may abut, or be in close proximity to, the panel inner surface when the panel edge portions are joined together.
A second wall is connected along an edge portion thereof to the inner surface of the panel and includes an opposite free edge portion. The second wall is configured to be longitudinally coextensive with the first chamber. The second wall edge portion is connected to the panel inner surface in generally parallel spaced apart relationship with the first wall edge portion such that the second wall is adjacent to the first wall free edge portion when the panel edge portions are joined together. The second wall inhibits electrical arcing from the power line into the first chamber between the first wall free edge portion and the panel inner surface. The second wall also increases the leakage length of the flashover protection cover.
Flashover protection covers according to the present invention can be provided in continuous lengths sufficient to cover spans of power lines of any length. A plurality of slots are formed in the first and second walls of the cover to facilitate winding or coiling the uninstalled cover around a spool or similar device. A live electrical power line is positioned between the arcuate first wall and the panel inner surface. The panel edge portions are then secured together to enclose the power line within the longitudinally extending chamber defined thereby. The plurality of slots that facilitate providing the cover in a generally flat uninstalled configuration are covered during installation with electrically-insulating material prior to securing the panel edge portions together. As the panel edge portions are secured together, the cover may be advanced along the power line span. Alternatively, a flashover protection cover, according to the present invention, may be applied to a live power line continuously. Installation operations are preferably performed via a remotely-controlled device which is either stationary or movable along a power line span.
According to another aspect of the present invention, flashover protection covers may include stress reduction hinges that facilitate reduced-stress bending of the flashover protection covers. By reducing bending-induced stresses, the stress reduction hinges can help reduce material failures, such as cracking, caused by thinning and/or inducing strain in the material during closing procedures.
Flashover protection covers according to the present invention are advantageous because they can be installed on existing power transmission lines without requiring the power lines to be removed from service. Covers according to the present invention provide electrical insulation sufficient to prevent power line flashover if adjacent power lines touch, such as during high winds, or if a grounded object, such as a tree or animal, makes contact with a power line. By reducing the potential for flashover, the possibility of power outages is diminished. Furthermore, hazards associated with flashover, such as fire, are also diminished.
REFERENCES:
patent: Re. 24613 (1959-03-01), Hageltorn
patent: 1224970 (1917-05-01), Singer
patent: 1485994 (1924-03-01), S
Kamel Sherif I.
Kayser George W.
Mabry, III Clyde Benton
Myers Bigel & Sibley & Sajovec
Nino Adolfo
Reichard Dean A.
LandOfFree
Flashover protection cover with stress reduction hinges does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flashover protection cover with stress reduction hinges, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flashover protection cover with stress reduction hinges will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2518430