Abstract:
An electric power distribution switch incorporates a stress-relieving connection structure, a closing guiding structure, a weather shield structure and a contact structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of application PCT/US2011/023921 filed Apr. 18, 2011, which application claims benefit of U.S. Provisional Patent Application No. 61/325,360 filed Apr. 18, 2010 for all purposes, the disclosures of these applications are hereby expressly incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This patent relates to commodity distribution and in particular to a switch for electric power distribution applications. 
         [0003]    Distribution switches can be configured to provide no-external-arc circuit interruption for overhead distribution feeders. Such switches are well suited for line switching (Including sectionalizing and feeder switching), transformer switching, cable switching and the like. Often configured to be gang-operated, i.e., a single operating mechanism switches all of the distribution phases. Such gang-operated switches may provide may provide a ground level manual operating handle or a vandal-resistant hookstick operating handle. The switches include an interrupter providing simultaneous, close three-pole interphase interrupting. 
         [0004]    While many configuration of distribution switches, such as the Omni-Rupter® Switch available from S&amp;C Electric Company of Chicago, Ill., United States of America, continuous improvement in the structure and function of such switches ensures enhanced operating capability and reliability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is perspective view of a distribution switch in accordance with the prior art. 
           [0006]      FIG. 2  is a perspective view of terminal connection to a switch of a distribution switch. 
           [0007]      FIG. 3  is a side view of the terminal connection of  FIG. 2 . 
           [0008]      FIG. 4  is a top perspective view of a contact assembly of a distribution switch. 
           [0009]      FIG. 5  is an enlarged view of the contract assembly of  FIG. 4  with the contact spring removed to enhance the view. 
           [0010]      FIG. 6  is a perspective view of a blade assembly of a destruction switch. 
           [0011]      FIG. 7  is a perspective view of a blade cam of the blade assembly of  FIG. 6 . 
           [0012]      FIG. 8  is a side view of the blade cam of  FIG. 7 . 
           [0013]      FIG. 9  is a top view of the blade cam of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  depicts a distribution switch  10  including a mounting member  12  so that the switch  10  may be mounted to a utility pole  14 . Many alternative mounting configurations are possible. The switch  10  includes a plurality of phase interrupting and switching assemblies  16 , and in the application for switch  10  three assemblies  16  corresponding to a three-phase distribution system. Each of the assemblies  16  is coupled to an operator  18  for simultaneous operation. 
         [0015]    Each assembly  16  includes a current interrupter  20  such as a vacuum interrupter, a blade assembly  22 , a blade contact assembly  24 , and terminal connections  26 . 
         [0016]    Switches, like the switch  10  incorporate pivoting hinges to allow rotation of the blade assembly  22  during opening and closing of the switch. The terminal pad for landing the high voltage conductor of the distribution system may be incorporated in the hinge design. A typical configuration, before the structures of the instant invention, uses a single-axis rotating contact. This configurations is sensitive to the alignment of the conductor to the hinge terminal pad, namely, the conductor needs to be well aligned with the hinge terminal pad to prevent uneven loading of he hinge structure. With large size conductors it is difficult to conform and land the conductors on the hinge terminal pad without applying an off-set or torsional load to the hinge terminal pad. Offset or torsional loading of the hinge assembly can cause uneven contact forces or misalignment of the blade and jaw contracts of the switch during closing. 
         [0017]    Referring to  FIGS. 2 and 3 , a terminal connection  26  is shown and includes a spherical hinge joint  28 . The hinge joint  28  incorporates a blade terminal portion  30  and a hinge terminal portion  32  secured to an insulator  34 . The blade terminal portion  30  is formed with a semi-spherical or convex surface portion  36 . The hinge terminal portion  32  mounts on the blade terminal portion  30  and is formed with a semi-spherical or convex surface portion  38  corresponding to the convex surface portion  36  such that the interaction of the portions  36  and  38  act as a bearing. Additionally, the portion  38  may be formed with buttons, bumps or other protuberances to contact the portion  36  to ensure good electrical contact. 
         [0018]    Both the blade  30  and the hinge  32  are formed with an aperture (not depicted) through which a post  40  extends, the post  40  being secured to the insulator  34 . The post has a groove end  36  on which a fastener clip  37  secures the blade  28  and the hinge  30  to the insulator along with washers and spacers, as necessary. A spring  44  is disposed between the washers  46  to provide damping force to ensure the hinge portion  32  always remains in contact with the blade portion  30 . Other securing and biasing techniques including staking, upsetting and the like may be used. Additionally, the aperture formed in the hinge portion  32  may be formed as slot  48  to allow it to rotate 360 degrees about the post  40  and additionally rotate upward ( FIG. 2 ) and downward ( FIG. 3 ) a predetermined amount, for example between about 10 and 15 degrees, for example 13 degrees, and to twist about its longitudinal axis between about +/−5 degrees, for example 3 degrees. 
         [0019]    The offset, twist and rotation of the hinge portion  32  are made without affecting contact force with the blade  30  or straining the terminal connection  26 . 
         [0020]    Alignment and loading of the terminal connection  26  by the conductor can also affect blade and contact engagement resulting in uneven or excessive contact forces and corresponding contact wear. Unusual contact forces and contact wear can reduce the current carrying capability of the terminal connection. Referring to  FIGS. 4-5 , a contact assembly  50  is of the jaw contact type and includes a plurality (two depicted) jaw contact buttons  52  of the corresponding jaw contact fingers  54  of a jaw contact  56  that float in apertures  58  formed in guide fingers  60 . The floating contact buttons arrangement allows evening of contact forces of the upper and lower jaw contacts. 
         [0021]    The width of the guide fingers  60  and deflection of the jaw contact fingers  54  is such that force to align the jaw contacts  56  and gradually spread the contact force over a large surface area of the blade  30 . The guide fingers  60  also provide a sacrificial arcing surface while closing the blade into high current faults or similar energized situations. The leading tips  62  of the guide fingers take the pre-strike arc erosion during fault dosing while leaving the jaw contact  56  surfaces undamaged. Additionally, the guide fingers  60  support the jaw contacts  56  from collapsing due to a biasing force of the contact spring  64  and from electromagnetic forces during high current situations, thus allowing elimination from the assembly of a spacer previously used to maintain the spacing of the jaw contacts  56 . 
         [0022]    During closing of the blade  30  the guide fingers  60  center the blade  30  as it enters into the contact assembly  50 . If the blade  30  is misaligned, the guide fingers  60  gradually center the blade  30  as it enters the contact assembly  50 . The guide fingers are spaced a predetermined amount wider than the thickness of the blade  30 , for example approximately 0.030 inch (0.762 millimeters). The guide fingers  60  further include a bumper  66  and guide block  68  that are adjustable on the mounting block  70  in order to align and center the guide fingers on the jaw contacts. Once the guide fingers  60  are aligned, the jaw contact buttons  52  protrude from the apertures  58 , for example approximately 0.050 inch (1.25 millimeter) to make contact with the blade  30 . 
         [0023]    The switch  10  incorporates for each phase a shunt interrupter  20 . The interrupter  20  is operated by engagement of a shunt-operating arm  70  with a cam  72  secured to the blade  30 . It is important for proper operation of the shunt interrupter  16  that the arm  70  properly latch with the cam  72  because failing to do so can result in the contacts in the interrupter  16  not opening correctly and the current not being interrupted. It is possible even that an external arc can result and a flashover of the switch  16 . 
         [0024]    Referring to  FIGS. 6-9 , the cam  72  is formed with an integral closing feature  74  to ensure the operating arm  70  is moved to the fully closed and latched position upon dosing of the associated switch  16 . An additional feature  76 , a multi-angled cam surface that allows resetting of the operating arm  70 . The surface  76  forces the flexible arm  70  over the conductive pin  78  during closing of the switch  16 . There is also a protruded shelf  80  on the cam  72  that acts as an ice shield to prevent formation of ice on the end of the blade  30 . Significant ice formation on the tip of the blade  30  conductive material can prevent the switch  16  from fully closing into the contact assembly  50 . A non-conductive material is chosen for the cam  72  that allows it and the ice shield  80  to act as a dielectric barrier between the arm  70  and the guide fingers  60  of the contact assembly  50   
         [0025]    The cam  72  is mounted to the blade  30  of the associated switch  16 . The conductive pin  78  that connects to the blade  30  is formed integral with the cam  72 , for example by in situ molding. The pin  78  actuates the operating arm  70  of the interrupter  20  during the opening sequence of the switch  16 . One the interrupter  20  trips open, the pin  78  continues to keep the interrupter  20  open until the arm  70  loses contact with the pin  78 . The arm  70  then returns to its closed position by action of an internal spring (not depicted). During dosing of the switch  16 , the surface  76  raises the arm  70  over the pin  78 . The integrated dosing stop  84  on the cam  72  ensures the interrupter  20  is closed, reset and ready for the next operation. 
         [0026]    While the invention is described in terms of several embodiments of switches, it will be appreciated that the invention is not limited to such structures. The inventive concepts may be employed in connection with any number of devices and methods of making and using such devices. 
         [0027]    Additionally, while the structures and methods of the present disclosure are susceptible to various modifications and alternative forms, certain embodiments are shown by way of example in the drawings and the herein described embodiments. It will be understood, however, that this disclosure is not intended to limit the invention to the particular forms described, but to the contrary, the invention is intended to cover all modifications, alternatives, and equivalents defined by the appended claims. 
         [0028]    It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph.