Abstract:
An expandable dielectric cover system for a pair of insulators supporting a conductor includes a first insulator cover and a separate insulator cover. A sleeve covers portions of the first insulator cover and second insulator cover and covers the conductor between the two covers. The sleeve covers a variable length of the first insulator cover and second insulator cover to accommodate a wide range of separations between the two covers while still covering the conductor. Pivotable arms are connectable to the other sides of the covers for covering a length of the conductor extending away from the sleeve.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to an insulating cover system for high voltage power line insulators and conductors (wires) and, in particular, to a cover system that is adapted to cover two insulators mounted a variable distance apart while still covering the conductor between the two insulators. 
       BACKGROUND 
       [0002]    A wood utility pole, formed from the trunk of a tree, is typically used for supporting high voltage (HV) conductors (e.g., twisted wire strands) in a power distribution system. Since the poles are formed from trees, the pole diameters vary from pole to pole. For example, the pole may have a diameter at the top of the pole of five inches, and four feet down from the top of the pole it may be ten inches. Another pole may have a diameter at the top of ten inches, and four feet down from the top it may have a diameter of fourteen inches. 
         [0003]    Each pole has secured to it one or more horizontal crossarms that support ceramic insulators which, in turn, support the HV conductors. Two crossarms are popular for their added strength and reliability. The crossarms are affixed to the pole using either bolts, a brace, a bracket, or other means. A conductor is typically affixed over the top of each insulator via a metal tie wire, a bracket, or other means. 
         [0004]      FIG. 1  is a side view of a top portion of a wooden pole  10 , looking into the ends of two horizontal crossarms  12  and  14 .  FIG. 2  is a top down view of the pole  10  of  FIG. 1  showing four sets of insulators supporting four conductors. The crossarms  12  and  14  are typically wood, such as 6 feet×3.5 inches×4.5 inches, depending on the support strength needed for the conductors. Material other than wood is also used for crossarms. 
         [0005]    Ceramic insulators  16  and  18  are affixed to the crossarms  12  and  14  by bolts  20 . A conductor  22  (typically twisted wire strands) seats in a groove in the insulators  16 / 18  or in some other securing feature, as previously described. 
         [0006]    The crossarms  12 / 14  in  FIG. 2  are shown supporting additional sets of insulators supporting additional conductors for 3-phase voltages. Alternatively, additional crossarms attached at different heights on the pole  10  may support the additional sets of insulators and the conductors for 3-phase voltages. The invention is applicable to all of the sets of insulators. 
         [0007]    Since the diameter of the pole  10  is variable, the separation of the insulators  16 / 18  is unknown prior to the pole  10  being assembled. Typical separations are 5-16 inches. 
         [0008]    Insulator covers, which are used in conjunction with extension arms that cover a length of the conductors, are frequently used for the protection of wildlife and preventing outages, permanent or momentary, due to shorts by trees, wildlife, debris, etc. The insulator/conductor covers are typically required to be 72 inches in length according to the Suggested Practices Guide developed by the Avian Power Line Interaction Committee (APLIC). Insulator/conductor covers measure 36 inches in one direction from the center of the insulator and 36 inches in the other direction. To obtain this 72 inch coverage, manufacturers have been designing these covers in three separate parts: the insulator cover, one extension arm connectable to one side of the insulator cover, and a second extension arm connectable to the other side of the insulator cover. 
         [0009]    For covering the insulators  16  and  18  in  FIG. 1  along with the conductor  22  between the insulators, such conventional covers would not work. This is because the distance between the insulators  16 / 18  varies from pole to pole, and an extension arm would be too long to fit between the insulators  16 / 18  and/or the extension arm would not precisely fit between the insulator covers. Additionally, the conductor  22  sags on one side of each insulator  16 / 18  due to the weight of the conductor  22  between poles, but the conductor  22  between the insulators  16 / 18  does not sag. The conventional extension arms could not accommodate the asymmetrical and variable conductor sag. 
         [0010]    A one piece double insulator cover, with a fixed conductor cover between them, will not work or fit correctly around the two insulators  16 / 18  since their separation is unknown until the pole is assembled. A wide variety of double insulator covers would have to be available to the lineman, while in the field, in different sizes or lengths to accommodate all the possible separations of the insulators. 
         [0011]    What is needed is a practical cover system for use with a pair of insulators supporting a conductor, where the separation between the insulators is variable. 
       SUMMARY 
       [0012]    The invention utilizes two insulator covers that are independent of each other and a separate sleeve that covers the conductor between the insulators. A single sleeve can accommodate a wide range of separations between the insulator covers. The insulator covers are asymmetrical and have one side that connects to an arm for covering the conductor and another side that faces the other insulator cover. The arm has a degree of movement that accommodates vertical and lateral angles of the conductor, while the sleeve is generally straight to accommodate the straight conductor between the insulators. 
         [0013]    The end portions of the sleeve overlap the tops of the insulator covers along a variable length of the insulator covers to enable the insulator covers to have variable separations while the end portions of the sleeve still overlap the insulator covers. For example, a single sleeve may accommodate a range of separations of the insulators of 5-14 inches. If the separation is greater than 14 inches, another sleeve may be selected in the field that can accommodate separations between 14-22 inches. In the embodiments described, each sleeve accommodates at least an 8 inch variation in insulator separation while still completely covering the conductor between the insulator covers. 
         [0014]    The cover arms are independent of each insulator cover and are attachable to the insulator covers without tools. 
         [0015]    Accordingly, the same multi-piece double insulator cover provides an adjustable fit for a range of pole diameters while accommodating a range of conductor angles. 
         [0016]    Other features of the cover system are also described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a side view of the top section of a wooden utility pole having crossarms, where ceramic insulators are supported on the crossarms for supporting a conductor. 
           [0018]      FIG. 2  is a top down view of the pole of  FIG. 1 . 
           [0019]      FIG. 3  is a side view of two insulator covers covering the insulators of  FIG. 2 , with extension arms attached to one side of each insulator cover for covering the conductor. The separation between the centers of the insulators is 14 inches. 
           [0020]      FIG. 4  is a top down view of the structure of  FIG. 3 . 
           [0021]      FIG. 5  is a top down view of the structure of  FIG. 4  after a sleeve has been placed over the insulation covers, where the sleeve covers the conductor between the insulator covers, and where the sleeve can accommodate separations between the insulators of 14-22 inches. 
           [0022]      FIG. 6  is a side view of the structure of  FIG. 5 . 
           [0023]      FIGS. 7-10  are identical to  FIGS. 3-6 , respectively, except that the insulators are 5 inches apart, and a sleeve is used that can accommodate separations between the insulators of 5-14 inches. 
       
    
    
       [0024]    Elements labeled with the same numerals may be identical or similar. 
       DETAILED DESCRIPTION 
       [0025]      FIG. 3  is a side view of a left insulator cover  26  and a right insulator cover  28 , each covering an associated insulator  16  and  18  from  FIG. 2 .  FIG. 4  is a top down view of the structure of  FIG. 3 . All materials may be polymers, such as PVC, or other type of moldable durable dielectric material. 
         [0026]    Each insulator cover  26 / 28  includes a bottom bell-shaped portion  30 , for covering the standard ceramic insulator, and a top portion  32  for covering the top of the insulator and the conductor  22 . The expanded bottom portion of the ceramic insulator is generally known as a skirt. In the example of  FIG. 3 , the separation between the centers of the insulators  16 / 18  is 14 inches, but a separation up to 22 inches can be accommodated by the same cover system. The conductor  22  is shown discontinuous between the insulators  16 / 18  to indicate that it is much longer than shown. 
         [0027]    The insulator covers  26 / 28  are positioned over the insulators  16 / 18 , and a pin  38  is inserted with a hot-stick or by hand through two holes in the cover  26 . An identical pin is used for the cover  28 . The pin  38  has a ring  40  at one end for the hot-stick and a resilient, expandable tip  42  at the other end. When the pin  38  is pushed through the holes, the tip  42 , being narrow at its end and tapered, compresses to easily pass through the holes. The tip  42  has a greater than 60 degree angle rim portion that makes it more difficult to remove. Therefore, the pin  38  remains held in place. The pin  38  is under the conductor  22 . Since the pin  38  is under the conductor  22 , the insulator cover  26  is blocked from being lifted off the insulator  16  and conductor  22  by wind. 
         [0028]    A left extension arm  36  attaches to the left insulator cover  26  with a vertically extending bolt  37 , or any other suitable vertical shaft. The arm  36  has a flange with a hole through which the bolt  37  passes. The flange pivots with respect to the bolt  37  to allow the arm  36  to accommodate bending of the conductor  22 . As seen in  FIG. 4 , the insulator cover  26  has a flared opening  46  for accommodating the bending of the conductor  22  without any stress. The arm  36  also has a degree of vertical movement with respect to the bolt  37 , which allows the arm  36  to accommodate sagging of the conductor  22 . 
         [0029]    The arm  36  is typically secured to the cover  26  by the manufacturer or otherwise secured before the cover system is taken into the field, so that tools are not required by the lineman for installing the cover system. 
         [0030]    The arm  36  has a set of holes through which is inserted a pin  44  under the conductor  22  for additionally loosely securing the arm  36  over the conductor  22 . The pin  44  has features similar to that of the pin  38  but may be shorter. 
         [0031]    Optionally, a retaining device, such as a plastic bolt  48 , is located on the side of the insulator cover  26 , below the ear of the insulator  16 , to prevent the cover  26  from lifting and potentially rotating about the insulator  16 . The bolt  48  is screwed in sufficiently to contact the narrow neck of the insulator  16  (shown in  FIG. 1 ) so as to block the cover  26  from rotating about the insulator  16 . The cover  26  is already blocked from coming off the conductor  22  by the pin  38 . 
         [0032]    The right insulator cover  28  and right extension arm  50  are a mirror image of the left insulator cover  26  and left cover arm  36  and have the same securing features. 
         [0033]    Since the separation between the insulators  16 / 18  is variable and the conductor  22  between the insulators  16 / 18  must be completely covered, a sleeve  54 , shown in  FIGS. 5 and 6 , is provided that fits over the tops of the insulator covers  26 / 28  to varying lengths, depending on the separation. The sleeve  54  has a bottom opening generally corresponding to a bisected cross-section of the insulator covers  26 / 28 , so any portion of the end sections of the sleeve  54  can fit directly over the insulator covers  26 / 28  and form a friction fit, which prevents the sleeve  54  from sliding after being positioned over the insulator covers  26 / 28 . Once the insulator covers  26 / 28  are installed, the sleeve  54  is simply centered with respect to the insulators  16 / 18  and pushed down over the covers  26 / 28  and center conductor  22  portion. A ring  55  attached to the sleeve  54  allows the sleeve  54  to be placed using a hot-stick. Holes are provided in the insulator covers  26 / 28  and arms  36 / 50  to allow them to be installed and removed with the same hot-stick. 
         [0034]    In the example, the sleeve  54  is about 18 inches long, and the exposed conductor  22  between the insulator covers  26 / 28  is about 10 inches long. The length of each insulator cover  26 / 28  that the sleeve  54  can fit over is about 4 inches, providing about 8 inches of acceptable variation between the insulators  16 / 18  (i.e., up to 22 inches) for the same sleeve  54 .  FIGS. 5 and 6  show the minimum separation between the centers of the insulators  16 / 18  (14 inches) for use with that particular sleeve  54 .  FIGS. 5 and 6  illustrate arrows  56  showing how the separation of the insulator covers  26 / 28  may be increased (up to 8 inches) while the sleeve  54  still rests on a portion of each insulator cover  26 / 28  for covering the center conductor  22  portion. 
         [0035]    Once the sleeve  54  is in place, a pin  56  is pushed through two holes near the bottom-center of the sleeve  54 , and under the conductor  22 , to secure the sleeve  54  in place. The pin  54  may be identical to the pin  38 . 
         [0036]    In another embodiment, a plastic bolt is inserted through the bottom hole of the sleeve  54 , instead of the pin  54 , and tightened to compress the sleeve  54  against the insulator covers  26 / 28  to more firmly secure the sleeve  54  to the covers  26 / 28 . 
         [0037]    Accordingly, since the lineman generally knows the range of separations of the insulators  16 / 18  for a particular type of pole  10  ( FIG. 2 ) but those separations may typically have an 8 inch range, the cover system of  FIGS. 3-6  can be used for the entire range of separations. 
         [0038]    In the example, the minimum separation between the insulators  16 / 18  for use with the sleeve  54  is 14 inches. If the separation were anywhere between 5 inches and 14 inches, a smaller sleeve would be used, as shown in  FIGS. 7-10 . In  FIGS. 7-10 , the same insulator covers  26 / 28  and arms  36 / 50  are used, but a shorter sleeve  60  ( FIGS. 9 and 10 ) is used since the separation between the insulators  16 / 18  is only 5 inches, and there is only 1 inch of the center portion of the conductor  22  exposed. In the example of  FIGS. 7-10 , the sleeve  60  is about 9 inches long, where the sleeve  60  overlaps each insulator cover  26 / 28  by 4 inches, and overlaps the 1 inch gap between the insulator covers  26 / 28 . The insulators  16 / 18  can be separated up to about 14 inches while the same sleeve  60  can be used to cover the conductor  22 . 
         [0039]    Accordingly, the same insulator covers  26 / 28  and arms  36 / 50  can be used for any practical range of separations between the insulators  16 / 18 , while only one or two sleeves  54 / 60  need be available to the lineman to accommodate a very wide range of separations. Typically, only one sleeve  54  or  60  will suffice for a particular distribution system. 
         [0040]    The sleeve  54 / 60 , insulator covers  26 / 28 , and arms  36 / 50  also prevent the covered structures getting wet so there can be no electrical short due to water. 
         [0041]    There are a variety of insulator shapes, and the insulators  16 / 18  are just examples. Other insulators are longer with sides having multiple ridges for higher voltages, and other insulators are simpler such as hemispherical with a connector, such as a vice, on top. The insulator covers  26 / 28  and sleeve  54 / 60  may be molded to accommodate any standard insulator shape while still retaining all aspects of the invention. 
         [0042]    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.