Abstract:
An improved pole mount cable restraint insulator is described featuring a pin and bolt locking mechanism that may be used to secure a medium voltage 5 kV to 35 kV electrical cable to the insulator and riser pole. The cable restraint insulator includes a seat to secure the cable. A further improvement over existing cable restraints is the polymer insulating materials used in the construction. Such materials are lighter in weight, electrically track resistant, lower in cost and non-breakable. The cable restraint insulator may be constructed by injection molding and/or casting with variety of electrically insulating polymers.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims priority from U.S. Provisional Patent Application Ser. No. 60/889,854, filed Feb. 14, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to overhead and underground power distribution equipment and, more particularly, to a pole mount cable restraint insulator. 
       BACKGROUND 
       [0003]    Electric utility companies use cable restraint insulators to mount power lines, such as medium voltage cables (for example, 5 kV to 35 kV), to riser poles and to bus bars in underground vaults or substations. These insulators typically feature two parts: 1) a clamp portion to secure the cables to the insulator and 2) a mount portion to secure the insulator to the riser pole or bus bar. Cable clamp portions must be constructed in many discreet sizes to accommodate various cable insulation diameters. A need therefore exists for an insulator with a clamp portion that can accommodate a variety of cable sizes. 
         [0004]    In addition, most often the clamp portions of insulators are constructed using metal and/or porcelain components. While such materials function well, improvements in terms of weight, cost and durability are desirable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of an embodiment of the assembled cable restraint insulator of the invention; 
           [0006]      FIG. 2  is an enlarged perspective view of one of the thread-less locking bolts and pins of the cable restraint insulator of  FIG. 1 ; 
           [0007]      FIG. 3  is a perspective view of the cable restraint insulator and thread-less locking bolts of  FIGS. 1 and 2  mounted on a pole and supporting power lines; 
           [0008]      FIG. 4  is an enlarged view of portion A of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0009]    An embodiment of the cable restraint insulator is indicated in general at  10  in  FIG. 1 . The insulator includes a pair of identical body halves indicated, indicated in general at  12  and  14 . As will be explained in greater detail below, body halves  12  and  14  are secured together by elongated retaining members, such as thread-less bolts  13  and  15 . 
         [0010]    Body half  12  attaches to a riser pole or bus bar (in an underground vault or station) or other structure by use of a mounting hole indicated at  16 . As used herein, the terms “pole” and “bar” mean the same structure. As illustrated in  FIG. 1 , the mounting hole may be counter bored to allow the use of an optional locking washer  18 , which is preferably constructed of metal. As an example only the washer preferably has a thickness of approximately 1/16″. The mounting hole  16  counter bore diameter is sufficient to allow the use of a standard or deep well hex-head or square-head bolt which is received by a bore in the riser pole or bus bore in addition to mounting hole  16 . 
         [0011]    As illustrated in  FIG. 1 , body half  12  features a pair of side tabs  20   a  and  20   b , while body half  14  features a corresponding pair of side tabs  22   a  and  22   b . Side tabs  20   a  and  20   b  feature fastener openings  24   a  and  24   b , while side tabs  22   a  and  22   b  feature corresponding fastener openings  26   a  and  26   b . Body halves  12  and  14  also feature center portions, indicated in general at  32  and  34 , respectively. In addition to the mounting hole  16 , the center portion  32  of body half  12  features a generally concave cable seat  36 . The center portion  34  of body half  14  features generally concave cable seat  38 . 
         [0012]    An enlarged view of thread-less bolt  15  is presented in  FIG. 2 . The thread-less bolt features a shaft portion  40  and a head portion, indicated in general at  42 . The shaft portion  40  features a number of spaced apertures  44  aligned with the longitudinal axis of shaft  40 . A locking pin  46  engages the apertures in a removable fashion. The head portion  42  of the thread-less bolt includes a flange  48 . As illustrated in  FIG. 1 , the shaft portion  40  of thread-less bolt  15  passes through the aligned tab openings  24   b  and  26   b  of body halves  12  and  14  with the flange  48  engaging the underside of tab  20   b . Locking pin  46  secures the assembled pieces together as shown in  FIG. 1 . 
         [0013]    Thread-less bolt  13  of  FIG. 1  features the same construction of thread-less bolt  15  and is received through the aligned tab openings  24   a  and  26   a  of body halves  12  and  14 . Locking pin  50  secures the assemble pieces together as shown in  FIG. 1 . 
         [0014]    While locking pins  46  and  50  are preferably metal spring pins (as illustrated in the figures), other types of fasteners known in the art may alternatively be used. Such fasteners may or may not require apertures in the thread-less bolts  13  and  15 . For example, the locking pin could instead clamp down on the shafts of thread-less bolts  13  and  15 . Such an arrangement may or may not require one or more grooves or slots formed in thread-less bolts  13  and  15 . In addition, standard threaded bolts could be substituted for thread-less bolts  13  and  15  as the elongated retaining members and nuts used in place of locking pins  46  and  50  as fasteners. As yet another alternative, a plastic one-time use “zip” bolt could be used which functions the same as a zip tie but features a shaft portion instead of the prior art tie portion. 
         [0015]    As illustrated in  FIGS. 3 and 4 , body half  12  of the cable restraint insulator  10  is mounted to a riser pole, indicated at  52 . As noted previously, the cable restraint insulator may be mounted to a bus bar or other structure in the same manner. One or more cables  54  are positioned in the seat of body half  12 . As illustrated in  FIG. 4 , body half  14  is positioned so that its seat is placed on the top of the cable(s). Installation of the thread-less bolts  13  and  15  and corresponding locking pins thru the body half tabs completes the installation of the cable restraint insulator. The multiple apertures along the shaft portions of thread-less bolts  13  and  15  permit the cable restraint insulator to accommodate cables of various diameters and various numbers of cables by allowing incremental adjustment of the spacing between cable seats  36  and  38  ( FIG. 1 ). 
         [0016]    The cable restraint insulator body halves  12  and  14 , and the thread-less bolts  13  and  15  are preferably constructed of injection molded track resistant high density polyethylene (HDPE). To those skilled in the art of molding and casting, however, it is apparent that the materials may be of any number of materials such as HDPE, epoxies (Cycloaliphatics), or polyurethane and also that the cable restraint insulator body and bolts may also be cast rather than injection molded. As indicated at  62  in  FIG. 1 , a number of slots may be molded into the body halves  12  and  14  to provide material and weight savings. 
         [0017]    As illustrated in  FIG. 1 , center portions  32  and  34  of the body halves each feature a pair of opposing bosses  64  and  66 , respectively, so that a slot is formed between each pair. The slots each receive a tab portion of a hanger bar or bracket, which is well known in the art, to allow an alternate hanger bracket mounting method. The slot of body half  14  is provided with slide member  68  to aid in securing the body half to the hanger bracket. Of course the slot of body half  12  features a similar slide member. 
         [0018]    The embodiment of the invention described above therefore provides an improved cable restraint mount insulator and clamping system that incorporates a unique adjustable arrangement and method for securing the cable in the hanger mount and, in the preferred embodiment, a HDPE insulating material. Such materials are lighter in weight, electrically track resistant, lower in cost and generally non-breakable. 
         [0019]    While the preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the invention, the scope of which is defined by the appended claims.