Electricity: conductors and insulators – Insulators – Special application
Reexamination Certificate
2000-02-25
2001-07-03
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Insulators
Special application
C174S0050SG, C174S139000
Reexamination Certificate
active
06255597
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to insulating covers and, more particularly, to insulating covers for electrical insulator bushings.
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 conventionally transmitted in phases wherein multiple conductors are utilized. One or more of these conductors may be a “hot” conductor that carries a specified amount of alternating current electric power. Flashover may result if contact is made between two hot conductors or between a hot conductor and ground. Non-grounded contact with a hot conductor, such as when a bird sits upon a hot conductor, typically does not result in flashover.
The transmission of electrical power from a generation source to residential areas typically involves a combination or transmission devices which make up a transmission system. In a typical transmission system, power is generated by a power plant such as a hydroelectric installation, a steam installation or a nuclear plant. The output from a power plant generator is normally about 25 kilovolts (kv). The output from a power plant generator is typically transmitted to a step-up substation where the voltage is increased to a transmission line voltage of 230 kv or higher. The next substation encountered is typically a transmission substation where the transmission voltage is decreased from the transmission line voltage to a sub-transmission voltage of approximately 69 kv. A distribution substation is then typically used to step the voltage down from the transmission voltage to a distribution voltage of about 5 to 35 kv. The distribution voltage is the voltage that is transmitted to a residential area, either through overhead or underground distribution systems. Single phase transformers are typically provided at the residential level to reduce voltage to a 240-120 volt, single phase, three wire residential power entrance.
Substations typically include various power transmission and distribution equipment, such as circuit breakers, transformers, capacitors, regulators, hook switches and the like. Uninsulated conductors typically extend between the equipment in a substation in various directions and configurations. To prevent arcing, electrical insulator bushings are typically provided about conductors at the point where the conductors extend from electrical transmission and distribution equipment housings.
Unfortunately, an electrical insulator bushing may act as a bridge for an animal moving between an uninsulated conductor and equipment from which the conductor extends. Although an electrical insulator bushing may prevent an animal from simultaneously touching the uninsulated conductor and the equipment, the length of some insulator bushings may be insufficient to prevent simultaneous contact between an uninsulated conductor and the equipment from which the conductor extends. As a result, animals climbing or perching on power transmission and distribution equipment may cause a short circuit or “flashover” between an uninsulated conductor and grounded equipment from which the uninsulated conductor extends. Flashover may result in power outages which are undesirable to electric power suppliers and to electric power consumers. As a result, devices for preventing animals from simultaneously contacting energized and grounded objects have been developed. For example, U.S. Pat. No. 5,864,096 to Williams et al. describes a disk-shaped guard having a number of spaced, concentric circular ring members of electrically insulating material configured to be mounted to insulator bushings of electrical power transmission and distribution equipment. U.S. Pat. No. 5,650,594 to Urnovitz describes a flat member configured to be releasably engaged on an insulator bushing extending from the upper end of a transformer. U.S. Pat. No. 5,794,495 to Anderson describes an animal guard having a pair of semi-circular-shaped body portions configured to be connected to a transformer insulator bushing.
Unfortunately, these existing devices are not designed to cover any portion of an uninsulated conductor extending from an insulator bushing. Because some wildlife, particularly large wildlife, may be able to circumvent these existing devices, it would be desirable to cover a portion of an uninsulated conductor extending from an insulator bushing.
Insulating covers for conductors are available. These covers conventionally include thick rubber tubing, heat-shrinkable tape, and wrap-around covers. Unfortunately, there are drawbacks associated with installing each of these types of covers. Thick rubber tubing can be somewhat bulky and difficult to install. Furthermore, tubing covers may require that a conductor be disconnected from service so that the conductor can be inserted through the tubing. Such electrical power service interruptions may be economically disadvantageous to an electric power supplier as well as being undesirable to electric power consumers.
U.S. Pat. No. 6,005,196 to Spillyards describes a spring-loaded cover configured to be secured about an electrical insulator bushing and a portion of an electrical conductor extending therefrom. U.S. Pat. No. 4,845,307 to Cumming et al. describes a single piece cover having an open slot so that the cover can be pushed or pulled over an electrical insulator bushing.
Unfortunately, a drawback associated with each of these protective covers is that the opening through which an electrical conductor extends may permit the ingress of pests, such as snakes, rodents, and other small animals. In the event that the cover must be removed at a later time, these pests would have to be contended with. In addition, each of these protective covers may be somewhat difficult to install remotely by a technician using a manipulator tool.
SUMMARY OF THE INVENTION
In view of the above, the present invention provides a wildlife guard that surrounds a portion of an electrical insulator bushing and a portion of an electrical conductor extending therefrom, and includes first and second cover portions formed from weather-resistant, electrically insulative material. The first cover portion includes opposite first and second end portions, and first and second elongated edge portions that extend between the first and second end portions. The first end portion of the first cover portion includes a first lever arm that extends beyond the first elongated edge portion. The second cover portion includes opposite third and fourth end portions, and third and fourth elongated edge portions that extend between the third and fourth end portions. The third end portion of the second cover portion includes a second lever arm that extends beyond the third elongated edge portion.
The first and second cover portions are pivotally coupled at the respective first and third end portions at a location intermediate of the first and second lever arms such that when a force is applied to the first and second lever arms by a portion of an electrical insulator bushing, the first and second cover portions pivot together into engagement in a closed position to define a hollow body that surrounds the electrical insulator bushing and a portion of the electrical conductor extending from the electrical insulator bushing. The first and third ends of the respective first and second cover portions are configured to surround an electrical insulator bushing between adjacent skirts when the first and second cover portions are in the closed position.
The second and fourth elongated edge portions each include a respective plurality of flexible fingers extending therefrom. The flexible fingers are in adjacent, contacting relationship when the first and second cover portions are in the closed position. The electrical conductor extends through the flexible fingers when the first and second cover portions are in the closed position.
A latch configured to maintain the first and second cover portions in the closed position may be provided. In addition one or more
Bowling David Edwin
Hiller Laura Jackson
Myers Bigel & Sibley & Sajovec
Nino Adolfo
Reichard Dean A.
Tyco Electronics Corporation
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