Triggered Wildlife Guard for Electrical Insulator Bushings

The present invention relates generally to an insulating wildlife guard for the electrical bushing of a distribution voltage transformer and more particularly to a novel and improved wildlife guard which is closed and locked by the activation of a trigger mechanism.

Many electric utility transformers are outdoor installations which in the past, have been subjected to possible damage and the creation of power outages due to contact with small mammals and birds. These animals tend to contact the energized conductors leading to transformer insulator bushings thereby creating a short circuit condition.

Most new transformers are now installed with protective, insulating guards on the transformer bushings, and these guards are easily installed by hand since this is done before the new transformer is energized. However, many transformers installed in the past did not include bushing guards of any type, and utilities are striving to retrofit these installations with guards which can be installed without disconnecting the power to the transformer. One such wildlife guard, shown in U.S. Pat. No. 4,845,307 to Cumming et al., is formed by a one piece unit having a lengthwise slot through which the live conductor to the transformer bushing is forced during the installation of the guard. This is somewhat difficult to accomplish from a distance, since the guard must be positively forced over a live conductor, and generally the use of a bucket truck and line crew would be required so that the guard could be brought close to the overhead transformer bushing for installation.

In an attempt to make installation easier, one piece tubular guards formed of two hinged semicircular cylinders have been designed to fit around a bushing and to engage when closed. Again, the problem with these hinged shields or guards is that they must first be carefully positioned relative to the insulator and live wire to the insulator and then the two hinged halves must be forced together around the insulator and locked in the closed position. This again is very difficult to achieve from a distance, and requires the use of a bucket truck and line crew to close the guard.

It is a primary object of the present invention to provide a novel and improved triggered wildlife guard which may be easily installed on a transformer bushing without disconnecting the primary electrical lead from the bushing.

Another object of the present invention is to provide a novel and improved triggered wildlife guard which may be easily installed using a conventional hot stick without requiring the use of a bucket truck and line crew.

A further object of the present invention is to provide a novel and improved triggered wildlife guard which, upon activation of a trigger, automatically closes and locks around the energized lead wire for a transformer bushing and which may then be easily positioned in the locked closed state over the transformer bushing terminal.

A still further object of the present invention is to provide a novel and improved triggered wildlife guard which automatically closes when triggered so that it may be easily installed from the ground with a long hot stick.

These and other objects of the present invention are accomplished by providing a novel and improved triggered wildlife guard which is substantially cylindrical in form and has a domed top wall with a central opening. The wildlife guard is a unitary unit having two side sections which are hinged along one edge and which latch together along an opposite edge. Spring units are provided along the hinged edge to bias the unit toward a closed and latched configuration, and a trigger mechanism is provided to hold the two halves of the wildlife guard apart. This trigger mechanism is released by contact with the lead wire for a transformer bushing and a stop is provided across the opening in the domed top of the wildlife guard to ensure that the energized lead wire is properly positioned before the guard is snapped to a closed and locked position. Flexible fingers are provided at the bottom of the guard which permit the guard to be moved downwardly over a transformer bushing terminal and which engage the bushing terminal help position the guard firmly on top of the bushing.

FIG. 1 is a perspective view of the triggered wildlife guard of the present invention in an open condition around a conductor for a transformer bushing;

FIG. 2 is a top plan view of the wildlife guard of FIG. 1;

FIG. 3 is a view in front elevation showing the upper portion of the wildlife guard of FIG. 1;

FIG. 4 is an exploded perspective view of the wildlife guard of FIG. 1; and

FIG. 5 is a view in front elevation of an embodiment of the triggered wildlife guard of the present invention.

Referring now to the drawings, the triggered wildlife guard of the present invention indicated generally at 10 is adapted to fit over a transformer bushing terminal 12 connected to an electrical lead line 14. The wildlife guard is formed from two segmental halves 16 and 18 which are hinged together along a hinge line 20. When the halves 16 and 18 are brought together, they form a cylindrical body having a closed domed top 22 at one end and a large circular opening 24 at the opposite end. The segmental halves 16 and 18 are molded from an electrically insulated, weather-resistant plastic such as polypropylene, and when joined formed a unitary, hinged unit. To hinge the halves of the wildlife guard together, projecting hinge elements 26 are integrally molded with the segmental half 18 and these hinge elements slide into slots 28 in hinge receiving blocks 30 molded on the segmental half 16. When the hinge elements 26 are mounted in the blocks 30, molded projecting springs 32 on the segmental half 18 engage molded projecting spring pads 34 on the segmental half 16 and spring bias the segmental halves of wildlife guard to a closed and latched position. The springs 32 are flexed and placed under tension by contact with the spring pads 34 when the hinge elements 26 are in placed in the receiving blocks 30.

In the closed and latched position of the triggered wildlife guard 10, a flange 36 along a leading edge of the segmental half 18 which is opposite to the hinge line 20 is received in a channel 38 between spaced flanges 40 and 42 molded on a leading edge of the segmental half 16 opposite to the hinge line. The bottom of the flange 42 is cut away at 44, and in the cutaway portion there is formed a molded latch 46 which engages a projection 48 projecting outwardly from the flange 36. When the segmental halves 16 and 18 are driven to a closed position about the hinge line 20 by the action of the springs 32, the projection 48 enters between the flexible hooked arms of the latch 46 and is retained thereby to lock the wildlife guard in the closed position. The combination of the flange 36 and the channel 38 insures that the projection 48 is guided into latching contact with the latch 46.

When the wildlife guard is latched in the closed position, a circular opening is formed in the domed top wall 22 by arcuate openings 50 and 52 formed in the segmental halves 16 and 18 respectively. Projecting above the arcuate openings 50 and 52 are L-shaped wire stops 54 and 56 having legs 58 and 60 which bridge the distance between the segmental halves of the wildlife guard when the segmental halves are open. As will be noted from FIG. 2, these legs 58 and 60 ensure that a wire 14 is positioned between the arcuate openings 50 and 52 when the segmental halves of the wildlife guard are open and that the wire is prevented from passing beyond the arcuate openings into the space between the segmental halves. The wire stops 54 and 56 include a cutaway portion 62 to receive the opposed leg 58 or 60 when the segmental halves of the wildlife guard close.

To hold the wildlife guard open for installation, a molded, electrically insulated trigger bar 64 is provided. This trigger bar is positioned adjacent to but inside the flanges 36 and 40, and has at least one free end 66 which engages a flat ledge 68 formed on the segmental half 18. The opposite end of the trigger bar 70 may be connected to the segmental half 16 by a thin, flexible plastic hinge 72. It will be noted in FIG. 1 that the trigger bar 64 is positioned adjacent the large opening 24 for the wildlife guard, while in FIG. 5, the trigger bar is positioned toward the center of the wildlife guard. The trigger bar may be connected at one end 70, as previously described, or both ends of the trigger bar may be free and rest against flat portions formed on the segmental halves 16 and 18.

To install the wildlife guard 10 on a bushing 12, an insulating hot stick is used to raise the wildlife guard above the bushing as shown in FIG. 1. Then, the top of the wildlife guard is moved inwardly until the energized lead 14 contacts the legs 58 and 60 of the wire stops 54 and 56. Next the lower portion of the wildlife guard is moved inwardly until the energized lead 14 contacts the trigger rod 64. As will be noted from FIG. 2, the trigger rod is inside the flanges 36 and 40 so that when the trigger rod pivots away from the flat portion 68 allowing the segmental halves 16 and 18 to snap together and lock, the lead wire 14 will be inside the closed wildlife guard. The trigger rod 64 is pivoted about the hinge 72 away from the flat 68 by moving the lower end of the wildlife guard 10 inwardly to force the lead wire 14 against the trigger rod 64 to dislodge the trigger rod. The trigger rod could additionally be dislodged by tapping the rod with a second hot stick.

Once the trigger rod 64 is dislodged and the segmental halves of the wildlife guard 10 spring shut around the hinge line 20 and lock, the wildlife guard will be closed about the lead wire 14 above the bushing 12. Now the wildlife guard can be moved down the lead wire and over the bushing terminal 12. Adjacent the bottom opening 24 of the wildlife guard are inwardly projecting flexible fingers 74 which are molded integrally with the segmental halves 16 and 18. These flexible projecting fingers extend inwardly around the circumferential extent of the wildlife guard. This enables these fingers to snap over the projections on the bushing 12 as a wildlife guard is lowered into place and to hold the wildlife guard in position over the bushing. These fingers also prevent wildlife from entering the wildlife guard through the opening 24.

The triggered wildlife guard of the present invention is easily installed on a bushing 12 using a conventional hot stick, and may easily be installed from the ground. The problem of the wire riding between the hinged halves of the wildlife guard which might be experienced with a normal hinged guard is alleviated by the wire positioning stops 54 and 56. Also, it is now not necessary to manually close an attempt to latch the two halves of the pivoted wildlife guard while maintaining the guard in position. Instead, the halves spring together when the trigger rod is disengaged and the flange 36 passes between the flanges 38 and 40 and positively guides the projection 48 into engagement with the latch 46. Thus, the closing and latching operation which is extremely awkward with the pivoted halves of a wildlife guard, and generally requires the use of a bucket truck and line crew is accomplished automatically with the triggered wildlife guard.

The triggered wildlife guard 10 provides a protective cover for a transformer bushing and lead wire which is designed to prevent power outages and equipment damage which might be caused by wildlife contact with an energized bushing. The wildlife guard may be easily installed using a single hot stick, and flexible fingers at the base of the wildlife guard fit the guard to bushing terminals of various sizes.