Patent Publication Number: US-11651872-B2

Title: Insertable pin for high voltage insulating covers

Description:
FIELD OF THE INVENTION 
     The invention relates to a dielectric retaining pin, installable using a hot stick, for retaining a dielectric cover over a high voltage fuse cutout or for retaining other covers over other high voltage components, where the cover protects birds and other animals from electrocution. 
     BACKGROUND 
     Applicant&#39;s own U.S. Pat. No. 10,679,815, incorporated herein by reference, describes a dielectric cutout cover held in place using dielectric retaining pins. The cover protects birds and other animals from electrocution, which may trigger an over-current condition that causes a power outage. 
     The present disclosure relates to improvements in the retaining pins, and descriptions of their use are presented to fully understand their function in improving the overall insulating properties of the resulting cover. 
       FIG.  1    illustrates a conventional fuse cutout  10 . A mounting bracket  12  secures a ceramic or polymer insulator  14  to a wooden utility pole or cross-arm used to support high voltage conductors, such as carrying 3-phase 12 KVAC or higher. A “hot” wire  16  is attached to one phase. A metal connector  18  electrically connects to the wire  16  to a top contact  20  of a blowable fuse  22 . The fuse  22  electrically connects to a pivot joint  24  and a bottom connector  26 . The bottom connector  26  is connected to another wire (not shown) which may lead to a transformer or any other electrical device or conductor. Opening or blowing of the fuse  22  disconnects the top contact  20  from the bottom connector  26 . 
     A metal hook assembly  28  is fixed to the connector  18  and is used to temporarily support a loadbreak tool for opening the fuse  22 . The bent hook assembly  28  is better shown in  FIGS.  7  and  8   . A metal pull ring  30  is physically and electrically connected to the upper end of the fuse  22 . The pull ring  30  always faces away from the pole or cross-arm. 
     The loadbreak tool has a metal hook that engages the pull ring  30  to allow the linemen to open the fuse  22  when the wire  16  is energized. The loadbreak tool also engages the metal hook assembly  28 . The loadbreak tool includes a spring-loaded switch that rapidly opens up the circuit to prevent an arc forming after the fuse  22  is pulled away from the top contact  20 . 
       FIG.  2    illustrates a dielectric cover  32  previously invented by the Applicant. The cover  32  also represents a similar design of other commercially available cutout covers that have a slot  34  in the back for placing the cover  32  over the cutout  10 , and removing the cover  32  from the cutout  10 , while the energized wire  16  is connected. In some covers, the slot may resiliently close after the wire  16  passes through. 
     The cover  32  covers the top and sides of the cutout  10 , including partially surrounding the metal hook assembly  28  and the pull ring  30  on their lateral sides. A flared-out portion  36  of the cover  32  is intended to allow easy access to the hook assembly  28  and pull ring  30  by the loadbreak tool. 
     The cover  32  has through-holes  38 ,  39 , and  40 . Depending on the type of insulator used, porcelain or polymer, one retaining pin is inserted through one hole (and its opposite hole) and another identical retaining pin is inserted through one of the remaining holes, such as by using a hot stick. The pins go below the cutout&#39;s metal connector  18  and top contact  20  to prevent the cover  32  being blown off the cutout. The same retaining technique may be used for any other type of cover for high voltage components to protect wildlife from electrocution. 
       FIGS.  3  and  4    are two views of a retaining pin  44 , described in Applicant&#39;s U.S. Pat. No. 8,963,011, incorporated herein by reference. The pin  44  has a ring  46  that engages a hook on a hot stick. At the other end of the pin  44  is a resilient portion  48  (a nose) with a narrow tip that expands outward at about a 15 degree angle. The resilient portion  48  allows the pin  44  to be inserted easily through the cover&#39;s holes  38 - 40  by the hot stick, but the top of the resilient portion  48  has a 45 degree angle, which makes it much more difficult to remove the pin  44 . A cross-section of the body  49  of the pin  44  is smooth and slightly oval. The pin  4  is formed of a polymer. Identical pins  44  extend below the metal connector  18  and the top contact  20  so the cover  32  does not blow off in high winds. 
     The pins  44  and cover  32  have been used in the field, and a flashover problem has been discovered in rare instances. Such a flashover incurs a substantial expense since a lineman must replace a fuse. The flashover issue was presented by the utilities company to the Applicant for analysis. The Applicant has concluded that the flashover was due to liquid running along the smooth body  49  of the pin  44  and creating a low resistance path between a high voltage component and a roosting bird. The bird may have been roosting on the cover  32  and contacted (or came close to) a ground or a different phase. The low resistance path between the ring  46  (on the outside of the cover) and the portion of the pin  44  closest to the high voltage components likely caused an arc between the bird (roosting on the cover  32 ) and the nearest grounded structure, such as a metal or wooden support structure. The liquid running along the pin&#39;s smooth body  49  in one case was due to a bird defecting on the pin  44  while perhaps perching on the cover  32 . Bird droppings contain a relatively high concentration of salt, which causes the liquid to be conductive. Alternatively, rain or snow may be the cause of the liquid running along the pin  44 . 
     What is needed is an improvement to the prior art cover and pin assembly that prevents flashovers due to conductive liquid running along the body of the pin  44 . 
     SUMMARY 
     A dielectric cover over high voltage components, such as for protecting wildlife from electrocution, is held in place over the components by dielectric pins that extend through holes in the cover, where the pins are manipulated by a loadbreak tool or hot stick. The pins vary in length depending on the voltage requirements of the cover and the size of the various components. A higher voltage requirement typically increases the size of the high voltage components and the size of the cover. The pins may vary between 3-12 inches in length. 
     Instead of the pin having a smooth body, the pin has a plurality (e.g., six or more) of circular ribs or skirts radially extending outward along the pin&#39;s body that greatly increase the surface leakage distance between the “outside” ring  46  of the pin and the area of the pin closest to the high voltage components under the cover. The ribs/skirts also prevent any liquid from being drawn along the body of the pin such as by gravity or capillary action. Thus, flashovers by bird droppings or contaminated water on the pins are prevented. 
     The ribs/skirts have a diameter smaller than the cover&#39;s through-holes so do not interfere with insertion or removal of the pin. Since the pins are injection molded, the ribs/skirts do not add any cost to the pins, yet provide a valuable advantage over the prior art pins. 
     In one embodiment, the pin&#39;s body is oval, so the skirts and ribs are also oval. The cover&#39;s holes may also be oval, so the pin is oriented in a particular way when inserted through the holes. The ring is perpendicular to the wide dimension of the oval, so the orientation causes the ring to be parallel with the ground for optimal engagement with the hot stick. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a side view of a conventional fuse cutout disclosed in Applicant&#39;s U.S. Pat. No. 10,679,815. 
         FIG.  2    is a perspective view of a prior art cutout cover that fits over the cutout and is held in place by retaining pins. 
         FIG.  3    is a front view and  FIG.  4    is a side view of an oval-shaped pin used to secure the cover over the cutout. 
         FIG.  5    is a perspective view of a dielectric retaining pin, in accordance with one embodiment of the invention, where concentric skirts (tapering outward) are distributed along the body of the pin. 
         FIG.  6    is a perspective view of a dielectric retaining pin, in accordance with another embodiment of the invention, where concentric ribs (generally constant thickness) are distributed along the body of the pin. 
         FIG.  7    is a semi-transparent side view of the cutout cover of  FIG.  2    being retained in place using the pin of  FIG.  5  or  6   . The cutout is using a relatively thick porcelain insulator, and one of the pins is inserted through a top set of holes that is not blocked by the insulator. 
         FIG.  8    is a side view of a cutout cover, similar to that of  FIG.  2   , being retained in place using the pin of  FIG.  5  or  6   . The cutout is using a relatively thin polymer insulator, and one of the pins is inserted through a bottom set of holes that is not blocked by the insulator. 
       Elements labeled with the same numerals in the various figures may be identical or similar. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS.  5  and  6    illustrate dielectric retaining pins  50  and  52  that are used to secure dielectric covers over high voltage components. The covers may be cutout covers, covers over insulators supporting wires, or any other type of insulating cover, typically for protecting wildlife from electrocution. 
     In one embodiment, the pins  50  and  52  are about 4 inches long, and the drawings have generally accurate relative dimensions. The pins  50  and  52  are an injection molded polymer. 
     The performance of the pins  50  and  52  is exactly like the pin  44  in  FIGS.  3  and  4   . The only difference is the skirts  54  in  FIG.  3    and the ribs  56  in  FIG.  6    along the body  58  or  60 . 
     In  FIG.  7   , the pin  50  or  52  is inserted through the cover&#39;s holes  38  and  40  ( FIGS.  2  and  7   ) until the expanded portion  62  of the pin  50  or  52  abuts the cover  32 . The expanded portion  62  provides one level of prevention of liquids entering the cover  32  via the pin  50  or  52 . 
     In the event there is a gap between the pin  50 / 52  and the cover, allowing a liquid to enter the cover  32  via the pin  50 / 52 , the skirts  54  or ribs  56  not only block the liquid from running along the body  58 / 60  but add a significant surface leakage distance along the body  58 / 60 . This greatly increases the flashover voltage and the insulating properties of the cover assembly in high moisture conditions. 
     In  FIG.  7   , the insulator  14  is a porcelain (ceramic) type, which is relatively thick. As such, the hole  39  is blocked by the insulator  14 . However, holes  38  and  40  are not blocked, so the pin  50 / 52  is inserted through those holes  38 / 40  and below the metal connector  18  and top contact  20  of the cutout to keep the cover  32  in place during high winds. 
       FIG.  8    shows the use of a similar cover  56  over a polymer insulator  66  that is narrower than the porcelain insulator  14  of  FIG.  7   . Pin  50  or  52  is inserted through holes  39  and  40  since the hole  39  is not blocked by the narrower insulator  66 . If the hole  38  is not blocked, a pin  50 / 52  can instead be inserted through the hole  38 . The pins  50 / 52  prevent the cover  32  being blown off in high winds. 
     The pin  50 / 52  can be used with many other types of dielectric covers that are used to protect wildlife from high voltage components. Such other covers include covers that are secured over an insulator supporting a wire, or covers over bushings for transformers, switches, etc. 
     Instead of the skirts  54  and ribs  56  shown, other types of designs may be used to increase the surface leakage distance along the pin&#39;s body. 
     In the example of  FIG.  5   , six skirts  54  are shown but any number of skirts can be used, as required. 
     Similarly, in the example of  FIG.  6   , fifteen ribs  56  are shown but any number of ribs can be used, as required. 
     In one example, the body  58 / 60  of the pin  50 / 52  has a diameter of about one-quarter inch, and the skirt  54  or rib  56  radially extends about 1/16-⅛ out of the body  58 / 60 . 
     The body  58 / 60  may be oval shaped, which means the skirts  54  and ribs  56  are also oval shaped. The holes in the cover  32  may be similarly oval shaped, and the pin  50 / 52  is oriented so the oval shapes are aligned. This also prevents the pin  50 . 52  from rotating after being inserted into the hole. The ring  46  is perpendicular to the wide diameter of the oval, so the ring  46  is generally parallel to the ground when the cover  32  and pin  50 / 52  are properly installed. This is an optimal angle for grasping the ring  46  with a hot stick. The resilient portion  48  of the pin  50 / 52  aligns with the wide part of the oval and is perpendicular to the ring  46 . 
     Any diameter the skirts  54  or ribs  56  may be adequate, depending on the moisture level. The skirts  54  or ribs  56  can instead take other forms of a plurality of radial portions extending outward from a centerline of the body  58 / 60  between the resilient portion  48  (the nose) and the grasping ring  46 . The radial portions have a diameter that is smaller than the holes in the cover  32 . 
     The pins  50 / 52  are inserted and removed via a hot stick to allow the cover  32  to be installed or removed while the conductor  16  is energized. 
     Other embodiments of pins are envisioned. For example, in some uses, the pins do not require the resilient ends to prevent the pins being unintentionally dislodged from the cover. In one embodiment, the pin  50 / 52  does not need to be pushed all the way through the cover  32 , since pushing the pin only partially through the cover  32  will still secure the cover  32  over the cutout. 
     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.