Abstract:
A dielectric cover system for an insulator supporting a high voltage conductor is molded to fit over the insulator to cover at least a top portion of the insulator and the conductor in contact with the insulator. A clip internal to the cover allows the cover to be freely placed over the insulator and then effectively restricts an inner diameter of the cover at a reduced diameter neck portion of the insulator, such that the clip blocks the cover from being lifted off the insulator and rotated about the insulator during high wind conditions. The clip is particularly effective where the conductor is supported in a side groove of the insulator, so the insulator and conductor form an asymmetric structure.

Description:
FIELD OF THE INVENTION 
     This invention relates to an insulating cover system for high voltage power line insulators and, in particular, to a cover system that is adapted to prevent the cover from tilting or rotating due to high winds while covering the insulator. 
     BACKGROUND 
     High voltage (HV) electrical distribution systems typically use utility poles or towers that support insulators, such as ceramic insulators, and the insulators support conductors that carry the high voltage. The ceramic insulators are affixed to the crossarms by bolts. The HV conductor (typically twisted wire strands) seats in a groove in the insulator and is affixed to the insulator via a metal tie wire. The groove may be on top of the insulator or on the side of the insulator. 
     Frequently, there are three parallel cables, each carrying a different phase. If there is a short to ground or a short between cables, a fuse or breaker will trip, causing a power outage or a rerouting of the electricity. A lineman must then fix the problem and refuse or reset the fuse/breaker. 
       FIG. 1  is a perspective view of a conventional ceramic insulator  10  that is mounted on a wooden pole (not shown) using conventional hardware, such as a bracket or a bolt. Round insulators are typically 4-8 inches in diameter. A bare cable  12  (a conductor) is secured to the insulator  10  by a wire (not shown) twisted around the insulator neck  13  and the cable  12 .  FIG. 2  is a top down view of the insulator  10  and cable  12 . For three phase distribution, there are typically two insulators/cables at the ends of a wooden crossarm and one insulator/cable supported in the middle or on the top of the pole. 
     When there is a straight run of the cable  12 , the cable  12  may be supported by the indent  14  at the top of the insulator  10  or may be tied to the side of the neck  13 . A twisted wire keeps the cable  12  in place. When the cable path needs to change direction, the cable  12  is bent around the neck  13  of the insulator  10 , as shown in  FIGS. 1 and 2 . 
     In locations where there are large birds, or other animals, dielectric cable shields (which include an insulator cover) are sometimes used to prevent such birds or animals contacting two or more of the-energized or grounded cables. 
     Prior art insulator covers for covering the insulator  10  in  FIG. 1  are typically designed for the symmetrical insulator/wire configuration, where the cable  12  is supported by the top indent  14  of the insulator  10 . If a prior art cover were used with the asymmetrical configuration of  FIG. 1 , the cover would undesirably seat at an angle over the insulator  10 . The cover is somewhat larger than the insulator, so there is some play between the cover and insulator. 
     Additionally, different conductor diameters may be used with the same type of insulator, where the diameter may be selected based on the required voltage or current transmitted or the distance between poles. This further creates unpredictability in the insulator cover&#39;s ability to be properly oriented with respect to the insulator and conductor. 
     In either the symmetrical or asymmetrical case, the prior art covers are not secured to the insulator  10  and cable  12 , and a high wind may catch the open underside of the cover and rotate it with respect to the insulator  10  and cable  12 , reducing the effectiveness of the cover in protecting wildlife and preventing shorts. If a cover is rotated, it may jeopardize the leakage distance of the insulator and electrically short the insulator. If a rotated or tilted cover is spotted, a lineman must reorient the cover. The problem with tilted covers is more extreme when the conductor is tied to the side of the insulator, as shown in  FIG. 1 . In  FIG. 1 , the rotation point of the cover may be around the off-centered cable  12 , so the cover more easily lifts off from the opposite side. This exact problem with prior art insulator covers has been reported to the present inventor by a power company, and the inventor was asked to design an improved insulator/conductor cover that did not rotate about the cable and insulator with high winds. 
     Therefore, what is needed is a practical cover system for an insulator/cable that can accommodate symmetrical and asymmetrical insulator/cable configurations and which cannot be rotated or even tilted when subjected to high winds. 
     SUMMARY 
     A semi-rigid insulator cover, in accordance with one embodiment of the present invention, has a shape that can accommodate both symmetrical and asymmetrical insulator/cable configurations while being in the same proper orientation. In one embodiment, the insulator cover has an internal securing clip, such as made of a dielectric plastic, that seats in the narrowed neck area of the insulator to prevent the cover from being lifted or rotated with respect to the insulator. 
     If the clip is rigid, the cover is placed over the insulator while being tilted to cause the clip to enter the narrowed neck area of the insulator. Then the cover is un-tilted to assume the proper position over the insulator while the clip becomes further inserted within the narrowed neck area of the insulator. If the clip is resilient, the cover may just be pushed down vertically over the top of the insulator, and the clip snaps into place after passing the ear portion of the insulator. 
     The lineman then inserts a pin through holes in the cover that extend just below the cable (supported by one side of the insulator neck). This prevents the cover from being lifted off (tilted) from the cable-side of the insulator. In one embodiment, there are two sets of the holes on either side of the insulator. The clip is located on the side of the cover opposite to the side that the cable is located. Therefore, the clip prevents the cover being lifted off (tilted) from the opposite side of the cable. 
     Since the cover is now restricted by both the pins and the clip, it can neither be lifted off the insulator nor rotated about the insulator. 
     The same cover may also be used when the cable is tied to the top of the insulator. However, if the pins are sufficiently close to the centered conductor, the clip may not be needed to prevent rotation but does not hamper the installation of the cover. In one embodiment, the clip can be easily removed from the cover without tools if not needed. 
     Different designs of covers, all including the clip, may be fabricated for use with different types of insulators, such as longer insulators having ridges. 
     In a preferred embodiment of the invention, the insulator cover also includes an arm attachment feature for a cable cover. As an additional securing feature, the arms include holes that are below the cables. A push pin is passed through the holes so as to additionally block the arms from being lifted off the cables. However, such pins, by themselves, may not prevent rotation of the cover system about the cable and insulator. The previously described securing clip prevents such rotation. 
     Other features of the cover system are also described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional ceramic insulator on a crossarm of a utility pole supporting a HV cable seated in a side groove of the insulator. 
         FIG. 2  is a top down view of insulator of  FIG. 1 . 
         FIG. 3  is a perspective view of an insulator/cable cover having an internal securing clip, in accordance with one embodiment of the invention. 
         FIG. 4  is a top down view of the cover of  FIG. 3 . 
         FIGS. 5A and 5B  are front and side views of a plastic pin that is inserted through holes in the cover and the arm attachments, and below the cable, for blocking removal of the cover and arm attachments from the cable. 
         FIG. 6  is a perspective view of the plastic clip secured to an insulator, where the remainder of the cover is invisible. 
         FIG. 7  is a right side view of structure of  FIG. 6 . 
         FIG. 8  is a perspective view of the clip. 
     
    
    
     Elements labeled with the same numerals may be identical or similar. 
     DETAILED DESCRIPTION 
       FIG. 3  is a perspective view of a semi-rigid insulator cover  16  and attachable arms  18 / 20  installed over an insulator  24  and cable  26 , where a securing clip internal to the cover  16  is secured to the cover  16  with a plastic bolt  28 . All materials may be polymers, such as HDPE, or other type of moldable durable dielectric material. The cover  16  does not significantly distort under high wind conditions. The insulator  24  is shown attached to a crossarm  30  of a utility pole. 
       FIG. 4  is a top down view of the cover  16 . 
     The insulator cover  16  includes a bottom bell-shaped portion  34 , for covering the standard ceramic insulator  24 , and a top portion  36  for covering the top of the insulator  24  and the cable  26 . Note how the cover  16  in  FIG. 4  is asymmetrically shaped to accommodate the cable  26  supported by the left side of the insulator  24 . If the cable  26  were on the other side of the insulator  24 , the cover  16  would be installed in the opposite orientation, so the same cover  16  accommodates the cable  26  being affixed on either side of the neck or on top of the insulator  24 . 
     A ring at the top of the bolt  28  allows the cover  16  to be placed over the insulator  24  using a hotstick. The bolt  28  and clip (shown in  FIG. 6 ) may be manually removed, to make space in the cover  16 , if the cable  26  was to be seated in the top groove of the insulator  24 . Therefore, the cover  16  fits the same over the insulator  24  whether the cable  26  is affixed to the top of the insulator  24  or to its neck  38  ( FIG. 6 ). 
     Typically, prior to installing the cover  16  over the insulator  24 , the arms  18  and  20  are attached to the cover  16  by vertical bolts  44 , which pivotally secure the arms  18 / 20  to the cover  16  via flanges. Each flange may be about one to two inches long, and has a hole at each end. One end is attached to the cover  16  by the bolt  44 , and the other end is pivotally attached by a bolt (not shown) to the respective arm  18 / 20 . This allows each arm  18 / 20  to not only pivot but to be displaced laterally to accommodate the cable  26  when it is off to one side of the insulator  26 , as shown in  FIG. 4 . In other words, the flange allows the arms  18 / 20  to be coaxial with the cable  26  even when the cable  26  is not centered with respect to the insulator  24 . The pivoting of the arms  18 / 20  also allows the arms  18 / 20  to accommodate a bend in the cable  26  around the insulator  24 . The cover  16  has flared openings  46  to allow the arms  18 / 20  to pivot without any stresses on the cover system. 
     The cover  16  has opposing holes, and each arm  18 / 20  has opposing holes, that are below the cable  26 . A pin  48  is inserted with a hot-stick or by hand through the two holes in the cover  16 . Similar pins  50  are used for the arms  18 / 20 . The pin  48  has a ring  52  ( FIG. 5A ) at one end for the hot-stick and a resilient, expandable tip  54  ( FIG. 5B ) at the other end. When the pin  48  is pushed through the holes, the tip  54 , being narrow at its end and tapered, compresses to easily pass through the holes. The tip  54  has a greater than  60  degree angle rim portion that makes it more difficult to remove. Therefore, the pin  48  remains held in place. The pins  48  and  50  are under the cable  26  to prevent the cover  16  and arms  18 / 20  from being lifted off the insulator  24  and cable  26  by wind. 
     To prevent the cover  16  and arms  18 / 20  from rotating with respect to the insulator  24  during high winds, an internal clip  56  ( FIG. 6 ), secured to the top of the cover  16  by the bolt  28 , seats in the area of the neck  38  of the insulator  24 .  FIG. 6  shows the clip  56  with the remainder of the cover  16  invisible. The bolt  28  fits through the hole  57  in the top of the clip  56 . The hole  57  may be threaded, or the bolt  28  is secured by a nut to the clip  56 .  FIG. 7  is a right side view of  FIG. 6 . 
     The clip  56  is designed to allow the cover  16  to be easily placed over the insulator  24  yet perform the securing function after the cover  16  has been placed over the insulator  24 . Other variations of the clip  56  are envisioned. 
     In one embodiment, the clip  56  is stamped out of a ⅛ inch thick, flat polymer sheet. The clip  56  is then bent, as shown in  FIG. 8 , under heat. The narrowed sections  58  of the clip  56  allow the flange portion  60  to easily bend with respect to the stationary base portion  62 . This allows the cover  16  to be pushed down vertically over the insulator  24 , where the flange portion  60  snaps into place within the neck  38  ( FIG. 6 ) of the insulator  24  after being somewhat straightened when being pushed over the ear  64  of the insulator  24 . The opening  66  in the clip  56  accommodates the ear  64 . 
     The flange portion  60  blocks the cover  16  from tilting upward in a counter-clockwise manner, as viewed in  FIG. 6 . Since the cable  26  is off-centered, and on the left side of the insulator  24 , the pins  48  ( FIG. 3 ) under the cable  26  prevent the cover  16  from tilting upward in a clockwise manner. 
     To remove the cover  16 , the bolt  28  may be removed from the cover  16 . Alternatively, the cover  16  may be removed by first removing the pins  48 / 50  then tilting the cover  16  in the direction of the flange portion  60  to lift the cover  16  off starting from the left side (in the configuration of  FIG. 6 ). 
     The clip  56  may also be formed so that the flange portion  60  does not easily bend. In such a case, the cover  16  is placed over the insulator  24  while tilted downward (toward the right in  FIG. 6 ) to first seat the flange portion  60  in the neck  38 , then straightened. 
     There are a variety of insulator shapes, and the insulator  24  is just one example. Other insulators are longer with sides having multiple ridges or skirts for higher voltages, and other insulators are simpler. An insulator having multiple ridges or skirts has multiple necks, and the securing clip may restrict the cover&#39;s inner diameter at any of the neck areas. The shape of the cover  16  is customized for each type of standardized insulator. 
     In another embodiment, the clip is secured to a side of the cover  16  rather than to its top. In another embodiment, the cover  16  is molded to form the clip integral with the cover  16 . In another embodiment, there is an identical clip  56  on both internal sides of the cover  16  for symmetrically preventing tilting of the cover  16 . In such a case, the clips  56  are resilient and snap over the ear of the insulator when the cover  16  is pushed over the insulator. 
     Having described the invention in detail, those skilled in the art will appreciate that, given the present disclosure, modifications may be made to the invention without departing from the spirit of the inventive concept described herein. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.