Abstract:
A portable load-breaking and pickup apparatus for handling a load associated with a power distribution system is disclosed. The apparatus includes first and second spaced-apart connectors electrically connected by a load break assembly. The load break assembly includes first and second outer contacts configured for mating engagement and configured to provide a low-resistance path between the first and second connectors, and first and second inner contacts configured for mating engagement and configured to provide a high-resistance path between the first and second connectors. The load break assembly transitions from an open position to a closed position in two stages. The two stages include closing the high-resistance path prior to closing the low-resistance path, and closing the low-resistance path after the high-resistance path has been closed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the field of the power distribution servicing and maintenance industries and, more particularly, to an apparatus for handling a load associated with a power distribution system. 
         [0002]    Over the years, power distribution systems have been developed which distribute power from various types of power generation facilities to end users such as residential and commercial customers. Today, power is still primarily distributed to residential and commercial customers using overhead-power-line networks. As used herein, an upstream direction along a power line will generally be in a direction toward a power generation facility or power source, and a downstream direction along a power line will generally be in a direction toward a customer, e.g., residential or commercial, or other user of power. 
         [0003]    These overhead-power-line networks require regular maintenance and repair to ensure proper operation, thereby ensuring that customers receive reliable and continuous power. Unfortunately, maintenance and repair work on overhead power lines can be quite dangerous. For example, cutting live power cables can result in dangerous electric arcing. 
         [0004]    Conventionally, an upstream switch must be opened before cutting any downstream portion of an overhead power line so that repairs or maintenance can be performed. However, opening an upstream switch associated with the power line cuts power to all customers downstream of the switch. An alternative approach is to provide a device that can break and return load to an overhead power line without the need to open the upstream switch. An exemplary load-breaking and load-returning apparatus is disclosed in commonly assigned U.S. Pat. No. 6,078,008, which is hereby incorporated by reference in its entirety. 
         [0005]    That being said, present day devices do not control arcing in a manner suitable for high amperage situations. The current devices work well for low amperage operations where controlling arc is of less importance; however, as utilities deal with higher amperages, a device that provides greater control of dangerous arcing is needed. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    These and other shortcomings of the prior art are addressed by the present invention, which provides a portable load-breaking and pickup jumper apparatus configured for controlled closing to mitigate dangerous arcing. 
         [0007]    According to one aspect of the present invention, a portable load-breaking and pickup apparatus includes first and second spaced-apart connectors electrically connected by a load break assembly. The load break assembly includes first and second outer contacts configured for mating engagement and configured to provide a low-resistance path between the first and second connectors, and first and second inner contacts configured for mating engagement and configured to provide a high-resistance path between the first and second connectors. The load break assembly transitions from an open position to a closed position in two stages. The two stages include closing the high-resistance path prior to closing the low-resistance path, and closing the low-resistance path after the high-resistance path has been closed. 
         [0008]    According to another aspect of the present invention, a portable load-breaking and pickup jumper apparatus includes a first connector configured for direct connection to a power line and a second connector electrically connected to the first connector. The second connector is electrically connected to the power line by a jumper cable. The apparatus further including a load break assembly electrically connected between the first connector and the second connector. The load break assembly includes first and second outer contacts configured for mating engagement and configured to provide a low-resistance path between the first and second connectors, and first and second inner contacts configured for mating engagement and configured to provide a high-resistance path between the first and second connectors. When the apparatus transitions from a closed position to an open position, the first and second outer contacts separate to break the low-resistance path while the first and second inner contacts remain engaged. The first and second inner contacts separate to break the high-resistance path once a pre-determined gap between the first and second outer contacts is achieved. When the apparatus transitions from the open position to the closed position, the first and second inner contacts re-engage prior to the first and second outer contacts to reestablish the high-resistance path and contain arcing within an insulator. The first and second outer contacts then re-engage to reestablish the low-resistance path. 
         [0009]    According to another aspect of the present invention, a portable load-breaking and pickup jumper apparatus includes a first connector configured for direct connection to a power line; a second connector configured for connection to a power line by a jumper cable, wherein when the apparatus is in a closed position, the second connector is electrically connected to the first connector to allow a flow of electricity through the apparatus; and a load breaking assembly electrically connected between the first and second connectors. The load breaking assembly includes a venting structure configured for axial movement and electrically connected to the second connector; an outer male contact connected to an end of the venting structure; an inner housing electrically connected to the first connector; an outer female contact connected to an end of the inner housing and configured for mating engagement with the outer male contact to provide a low-resistance path; an insulating sleeve positioned inside of the inner housing; a probe assembly electrically connected to the first connector and positioned in the insulating sleeve, the probe assembly including a contact portion and an insulating portion; and an inner female contact secured in electrical contact with the outer male contact by the insulating sleeve. The inner female contact includes a plurality of fingers extending into the insulating sleeve for engagement with the contact portion when in the closed position to provide a high-resistance path. When the apparatus is transitioned from the closed position to an open position, the venting structure is pulled outwardly from the apparatus. The outer male contact separates from the outer female contact to break the low-resistance path. The inner female contact and the contact portion remain engaged until a pre-determined gap between the outer male and female contacts is achieved and then separate to break the high-resistance path. When the apparatus is transitioned from the open position to the closed position, the venting structure is released to allow the venting structure to move inwardly towards the apparatus. The inner female contact and contact portion engage to reestablish the high-resistance path prior to engagement between the outer male and female contacts, thereby containing arcing in the insulating sleeve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0011]      FIG. 1  is a fragmentary perspective view of a portable load-breaking and pickup jumper apparatus in accordance with an embodiment of the invention; 
           [0012]      FIG. 2  is a perspective view of the apparatus of  FIG. 1  positioned on a power line; 
           [0013]      FIG. 3  is a plan view of the apparatus of  FIG. 1 ; 
           [0014]      FIG. 4  is a cross-sectional view of the apparatus of  FIG. 3 ; 
           [0015]      FIGS. 5A and 5B  are cross-sectional views of internal parts of the apparatus of  FIG. 3 ; 
           [0016]      FIG. 6  is a cross-sectional view of a trigger assembly of the apparatus of  FIG. 3 ; 
           [0017]      FIG. 7  is an exploded view of the internal parts of the apparatus of  FIG. 3 ; and 
           [0018]      FIGS. 8-11  are cross-sectional views of the apparatus of  FIG. 3  showing interaction of the internal parts as the apparatus moves from the closed position to the open position and back to the closed position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring to the drawings, an exemplary portable load breaking and pickup jumper apparatus according to the present invention is illustrated in  FIGS. 1-3  and shown generally at reference numeral  20 . The apparatus  20  is designed to be placed onto a power line  10  to quickly break and return a load to portions of the line  10 . 
         [0020]    The apparatus  20  typically includes a first connector  21  positioned at a first end  22  of the apparatus  20  for direct connection to the power line  10  and a second connector  40  positioned on a second end  41  of the apparatus  20  to allow a jumper cable  14  to be connected between the connector  40  and the power line  10 . 
         [0021]    The first connector  21  and second connector  40  are formed from one or more conductive materials. The first connector  21  includes a clamp head  23 , a threaded clamp body  24  having a clamping surface  26  (i.e., cut away or grooved portion) and a hook portion  27 , and a top cap  28  connected to the threaded clamp body  24 . The clamp head  23  includes an upper hand guard  29  and an upper outer housing  30  which can be manually gripped by a hand of a user to thereby threadingly adjust the first connector  21  between open or closed positions. As understood by those skilled in the art, other types of power line connectors can be used for the first and second connectors according to the present invention. For example, a clamp applied with a gripping style hotstick or utility tool known as a “shotgun stick” by those skilled in the art, can be used as well. 
         [0022]    A lower outer housing  31  extends between the first connector  21  and the second connector  40 ; thereby extending a portion of the lower outer housing  31  into an interior of the upper outer housing  30 . The upper and lower outer housings  30  and  31  are typically formed from one or more insulating materials, such as fiberglass. 
         [0023]    The second connector  40  includes a collar  43  connected to a lower end of the lower outer housing  31  and a conductor bar  42  connected to the collar. A reset trigger assembly  60  is also connected to the collar  43 . The reset trigger assembly  60  may be triggered using a hotstick  18  or other suitable device. As shown, a first end  13  of the jumper cable  14  is connected to the conductor bar  42  using a first clamp  15  and a second end  16  of the jumper cable  14  is connected to the power line  10  using a second clamp  17 . 
         [0024]    A venting structure  44  having vents  45  is contained in the lower outer housing  31  and extends through a bore of the second connector  40 . The venting structure  44  is slidable axially along the apparatus  20  to transition the apparatus  20  between a closed position and an open position. An engaging ring  46  is connected to a first end  48  of the venting structure  44  to allow a hotstick  18  or other suitable device to engage the ring  46  and allow a user to pull the venting structure  44  outwardly from the lower outer housing  31 , thereby transitioning the apparatus  20  from the closed position to the open position. A spring  47  biases the venting structure  44  towards a closed position. As the apparatus  20  transitions from the closed position to the open position, the spring  47  is compressed. The compression of the spring  47  provides a force that enables the apparatus  20  to automatically return to the closed position. 
         [0025]    Referring to  FIGS. 4-7 , the apparatus  20  includes an inner housing  50 . A first end  51  of the inner housing  50  is connected to the threaded clamp body  24  and a second end  52  of the inner housing  50  is connected to an outer female contact  53 . A mating outer male contact  54  is connected to a second end  56  of the venting structure  44 . As illustrated, the spring  47  surrounds the venting structure  44  and is held in position between the male contact  54  and the second connector  40 . The outer female and male contacts  53  and  54  are formed of a conductive material, such as brass. 
         [0026]    An insulated sleeve  70  resides inside of inner housing  50  and includes first and second ends  71  and  72 , respectively. The second end  72  of the sleeve  70  is connected by threaded engagement to the outer male contact  54 . A toggle assembly  73  having a toggle  74  is connected to the first end  71 . An inner female contact  76  is secured between the second end  72  and the outer male contact  54  by compression. The inner female contact  76  includes a flange  77  for being compressed by the second end  72  and the outer male contact  54  and a plurality of fingers  78  extending outwardly from the flange  77  into an interior of the insulating sleeve  70 . 
         [0027]    The insulating sleeve  70  is configured to receive a probe assembly  80  therein. Probe assembly  80  includes a first end  81  having a load break spring  82 , a spring connector  83 , and a ramped rod connector  84 . As shown, spring connector  83  is connected to a first end  86  of the spring  82  and rod connector  84  is connected to a second end  87  of the spring  82 . The spring connector  83  secures the probe assembly  80  to an inside surface of the threaded clamp body  24 . 
         [0028]    A rod  88  having first and second ends  89  and  90 , respectively, is connected to the rod connector  84  by first end  89  such that the rod  88  extends outwardly from the first end  81  and into the insulated sleeve  70 . The second end  90  of the rod  88  includes a contact portion  91  for engaging inner female contact  76  and an insulated portion  92  for disengaging the contact portion  91  from the inner female contact  76 . Insulating arc tubes  93  are positioned over the rod to control arc. The contact portion  91  and the inner female contact  76  are formed of a conductive material, such as brass. 
         [0029]    Trigger assembly  60  is connected to the collar  43  and includes a lever  61 , a trigger guard  62 , a trigger spring  63 , and a trigger plug  64 . In a non-use position, the lever  61  compresses the spring  63  against the plug  64  which is compressed against the venting structure  44 . When the venting structure  44  is pulled outwardly to transition the apparatus  20  from a closed position to an open position, the plug is pushed into a locking groove  66  to secure the apparatus  20  in the open position. When the lever  61  is depressed, the spring  63  is decompressed, thereby allowing the plug to disengage the locking groove  66  which in turn allows the apparatus  20  to transition from the open position to the closed position. Lockout provisions may also be incorporated with the trigger assembly  60 . This provisions include inserting a lockout bolt to prevent the trigger from being depressed or to prevent the venting structure  44  from moving, placing a cover over the trigger assembly  60  which prevents a user from accessing the assembly  60 , or any other suitable provision. 
         [0030]    Referring now to  FIGS. 8-11 , in general, to facilitate the transition between the closed position and the open position, the apparatus  20  typically includes a low-resistance current path and a high-resistance current path. In the closed position, both the low-resistance current path and the high-resistance current path are typically closed, whereas, in the open position, both paths are open. During the transition from the closed position to the open position, the low-resistance current path will typically open before the high-resistance current path. 
         [0031]    In the closed position,  FIG. 8 , the apparatus  20  provides a low-resistance current path from the first connector  21  to the second connector  40 . As shown, the outer male contact  54  is in mating engagement with the outer female contact  53  and the inner female contact  76  is in mating engagement with contact portion  91 . Additionally, toggle  74  is in mating engagement with rod connector  84 . In order to transition the apparatus  20  to an open position, a user uses hotstick  18  to pull the venting structure  44  outwardly from the lower outer housing  31 . 
         [0032]    As the apparatus  20  transitions from the closed position to the open position,  FIG. 9 , the low-resistance path is broken by separation of the outer male contact  54  from the outer female contact  53 . Additionally, the load break spring  82  is expanded due to the toggle  74  being engaged with the rod connector  84 . The inner female contact  76  and contact portion  91  are still in mating engagement to maintain the high-resistance path. 
         [0033]    Once sufficient gap is achieved between the outer male contact  54  and the outer female contact  53  to withstand the voltage after the load break operation, the toggle  74  toggles from an engagement position to a non-engagement position by an interior surface of the first inner housing  50 ; thereby, disengaging the toggle  74  from the rod connector  84  and releasing the load break spring  82  to move from an expanded position to a normal position,  FIG. 10 . This in turn causes the probe assembly  80  to move upwardly towards the threaded clamp body  24 ; thereby disengaging the inner female contact  76  from the contact portion  91 . This disengagement occurs rapidly as the load break spring  82  retracts and allows the disengagement to occur within the insulating arc tubes  93 ; thereby breaking the high-resistance path and the electrical arc quickly and safely. The venting structure  44  is continued to be pulled outwardly from the lower outer housing  31  until the trigger plug  64  engages the locking groove  66  to maintain the apparatus  20  1in the open position. Venting of hot gasses from the transition between closed and open positions, escape down the venting structure  44  and out vents  45 . 
         [0034]    In order to transition the apparatus  20  from the open position to the closed position, a user depresses lever  61  using the hotstick  18  or other suitable tool. Once the lever  61  has been depressed, the trigger plug  64  is allowed to disengage the locking groove  66 ; thereby allowing the venting structure  44  to move inwardly towards the lower outer housing  31 . As discussed above, the spring  47  is compressed during the transition from the closed position to the open position and, as a result, the spring  47  forces the venting structure  44  inwardly as it expands to a non-compressed position. 
         [0035]    Generally, it is known in the industry that when two contacts are closing into one another and an AC voltage exists between the two, there will always be an arc before the contacts actually touch. As the gap between the contacts narrows, the sine wave feature of AC voltage continually changes the voltage difference between the contacts. The arc always seems to form at the point when the AC wave is at its peak. This being the case, picking up electrical load can cause damaging arcing, particularly when dealing with high amperage situations. 
         [0036]    As the venting structure  44  moves inwardly, a two stage closing occurs to pick-up the electrical load and minimize damaging arcing. First, the inner female connector  76  comes into contact with the contact portion  91 . This allows the temporary path or high-resistance path to close first inside the insulating arcing tubes. As the inner female connector  76  comes into contact with the contact portion  91 , the fingers  78  make initial contact with the contact portion  91  and then slide over the contact portion  91  for a pre-determined distance to provide overlapping. As the fingers  78  slide over the contact portion  91  in an overlapping manner, the outer male contact  54  and outer female contact  53  engage to close the low-resistance path. Because of the two stage closing, the damaging arcing is contained. 
         [0037]    As the inner and outer contacts close, hot gases are vented out of the apparatus  20  through the venting structure  44  and out the vents  45 . 
         [0038]    The foregoing has described a portable load-breaking and pick up jumper apparatus. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.