Abstract:
A junction assembly has a first electrically conductive junction having at least one inlet and a second electrically conductive junction having at least one outlet. A plurality of electrically conductive flexible connectors are disposed between and attached to the first and second junctions. A casing surrounds the inlet and the outlet such that coolant can flow in from the inlet, throughout the interior of the casing interior, and out through the outlet.

Description:
FIELD OF THE INVENTION 
     The present invention relates in general to a gas cooled electrical junction assembly, and more particularly, to a gas cooled electrical junction assembly located between a parallel ring and main lead used in a turbine generator within a power generation plant. 
     BACKGROUND OF THE INVENTION 
     Many power generation plants produce electricity by converting energy (e.g. fossil fuel, nuclear fission, hydraulic head, geothermal heat) into mechanical energy (e.g. rotation of a turbine shaft), and then converting the mechanical energy into electrical energy (e.g. by the principles of electromagnetic induction). Fossil fuel power generation plants typically use a turbine to convert the fossil fuels into mechanical energy and a generator to convert the mechanical energy into electricity. 
     One aspect of the above-described power generation scheme involves a junction assembly that is located between the generator&#39;s parallel rings and the generator&#39;s main lead. The junction assembly conducts AC electrical current from the parallel rings to the main lead. The junction assembly must also accept and attenuate the vibration that the parallel rings and coil windings place upon it, as well as withstand the high temperature caused by the electrical current that runs through it. 
     As shown in FIG. 1, to meet these requirements, a conventional junction assembly  10  typically comprises several flexible connectors  12  (sometimes set back-to-back) secured to a thin, flat elongated junction  14 . The flexible, connectors  12  are constructed of conductive wire strands  16  to provide an electrically conductive path and to provide the junction assembly  10  with flexibility to accept the various and varying forces and loads applied by the parallel rings  20 , main lead  22  and other generator components. The junction  14  secures the flexible connectors  12  relative to the parallel rings  20  and main lead  22 , and has a passageway  18  through which a coolant flows to cool the flexible connectors  12  by conduction. 
     There are several shortcomings, however, to the above-described conventional junction assembly. One shortcoming involves the tracked coolant route, which causes any and all cooling of the flexible connectors to be performed by conduction along and from the passageway. Another shortcoming of the tracked coolant route involves the undesirable overcooling of flexible connectors located near the coolant inlet and undercooling of flexible connectors located near the coolant outlet. 
     There is thus a need for a junction assembly that more efficiently cools the flexible connectors. There is also a need for a junction assembly that more uniformly cools the flexible connectors. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention thus involves a junction assembly comprising a first electrically conductive junction having at least one inlet; a second electrically conductive junction having at least one outlet; a plurality of electrically conductive flexible connectors disposed between and attached to the first and second junctions; and a casing surrounding the inlet and the outlet, whereby coolant can flow in from the inlet, throughout the casing interior, and out through the outlet. 
     Another aspect of the invention involves method of cooling an electrically conductive element comprising providing at least one electronically conductive element disposed between and attached to a second and a third electrically conductive element, the second and third elements each having at least one opening; providing a casing that surrounds the openings in the second and third elements; and flowing coolant through the opening in the second element and through the opening in the third element such that the coolant cools the first element. 
    
    
     Further aspects, features and advantages of the present invention will become apparent from the, drawings and detailed description of the preferred embodiments that follow. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other concepts of the present invention will now be addressed with reference to the drawings of the preferred embodiments of the present invention. The illustrated embodiments are intended to illustrate, but not to limit the invention. The drawings contain the following figures, in which like numbers refer to like parts throughout the description and drawings and wherein: 
     FIG. 1A is a side elevation view of an exemplary prior art generator junction assembly; 
     FIG. 1B is a side elevation view of another exemplary prior art generator junction assembly; 
     FIG. 2 is a side elevation view of the junction assembly of the present invention, showing a casing surrounding an inlet and an outlet; 
     FIG. 3 is a side elevation view of another embodiment of the junction assembly of the present invention; 
     FIG. 4 is a side elevation view of a portion of the junction assembly; and 
     FIG. 5 is a top elevation view of another embodiment of the generator junction assembly of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention described herein employs several basic concepts. For example, one concept relates to a junction assembly that more efficiently cools the flexible connectors. Another concept relates to a junction assembly that more uniformly cools the flexible connectors. Another concept relates to a gas cooled junction assembly. 
     The present invention is disclosed in context of an exemplary generator junction assembly located between a generator&#39;s parallel rings and a generator&#39;s main lead. The principles of the present invention, however, are not limited to generator junction assemblies located in this particular area, and can be used in connection with other areas within a generator that have similar cooling requirements. It will be understood by one skilled in the art, in light of the present disclosure, that the present inventions disclosed herein can also be successfully utilized in connection with junction assemblies outside the generator field and outside the power generation field that have similar cooling requirements. One skilled in the art may also find additional applications for the apparatus, components, configurations and methods disclosed herein. Thus, the illustration and description of the present invention in context of exemplary junction assemblies is merely one possible application of the present invention. However, the present invention has been found particularly suitable in connection with generator junction assemblies. 
     To assist in the description of the invention described herein, the following terms are used. Referring to FIG. 3, a “longitudinal axis” (X—X) extends along a length of the junction  34 . A “lateral axis” (Y—Y) extends along another length of the junction  34 . A transverse axis” (Z—Z) extends normal to both the longitudinal and lateral axes, and provides the third or depth dimension of the junction  34 . In addition, as used herein, the “longitudinal direction” or “longitudinal length” refers to a direction substantially parallel to the longitudinal axis, the “lateral direction” or “lateral length” refers to a direction substantially parallel to the lateral axis, and the “transverse direction” or “transverse length” refers to a direction substantially parallel to the transverse axis. 
     FIG. 2 shows a junction assembly  30  comprising a plurality of flexible connectors  32  and a pair of junctions  34  located between a generator&#39;s parallel rings  20  and a generator&#39;s main lead  22 . The junction assembly  30  includes a casing  42  that surrounds the flexible connectors  32  and junctions  34 . The casing  42  (as illustrated in FIG. 2) or the end of the junctions  34  (as illustrated in FIG. 4) have at least one inlet  36  or outlet  38  (more generally, opening  40 ) through which a coolant (e.g. air, hydrogen, water) flows to cool the flexible connectors  32  and junctions  34 . The coolant typically flows at a rate of between about 5 cubic feet per minute, depending on the particular generator with which the junction assembly is used. Suitable coolant pressure is about 2 pounds per square inch to about 10 pounds per square inch. 
     The number and size of openings  40  through which the coolant flows (i.e. total cross sectional surface area) will also vary depending on the particular generator, coolant, flow rate, pressure, etc. with which the junction assembly is used. For example, hydrogen is about 7 times more efficient than air for cooling purposes. In general, a total cross sectional surface area of about 0.1 inch to about 10 inches is suitable. For example, if used with a an air-cooled generator having about 20,000 to about 30,000 amps of current running through the junction assembly with a flow rate of about 10 cubic feet per minute at a pressure of about 5 pounds per square inch, a total flow rate of about 1 to about 3 inches is suitable. 
     The illustrated embodiment shows one junction  34  having three openings  36  and the other junction  34  having two openings  38 . The openings need not be located in any particular place, and can be disposed uniformly across the longitudinal length of the junction  34 , towards the end, sides or perimeter of the junction  34  (where AC current crowding causes higher temperatures), randomly, and the like. For ease of construction, the illustrated openings  40  have a generally cylindrical or elliptical shape and extend generally perpendicular to the flexible connectors  32 . However, each opening can have a variety of cross-sectional shapes, such as linear, curved, curvilinear, combinations thereof and the like, and can have an overall path that is linear, curved, curvilinear, combinations thereof and the like, and be disposed in uniform relation to other openings or not so disposed. The openings can also be rifled to help swirl and distribute the coolant through the casing. Further, the opening can also be angled to help direct the coolant to particular areas within the casing, such as where the flexible connectors are located. A flow rate controller (not shown), such as an orifice or restrictor valve can be used to control the flow rate or pressure of the coolant. The openings can also thus have a showerhead type configuration. 
     Still referring to FIG. 2, a casing  42  surrounds the inlets  36  and outlets  38  to provide a structure within which the coolant is free to move. The casing  42  also provides a restraining mechanism that directs the coolant entering the inlets  36  to exit the outlets  38 . The casing  42  is advantageously hermetically sealed, but need not be so. By this configuration, the coolant, particularly when in gas form (i.e., air or hydrogen) can cool the flexible connectors  32  by radiation, as well as by convection and/or conduction. Cooling by radiation provides for a more efficient and even cooling of the flexible connectors  32 . 
     The casing  42  can be embodied in a variety of three dimensional shapes, such as cubical, parallelepiped, prism, cylindrical, spherical, ovoid, discus, conical, pyramidal and the like. FIG. 2 shows the casing  42  having a generally spherical shape. 
     The casing  42  preferably has a total volume of about 0.1 cubic foot to about 5 cubic feet, depending on the particular generator with which it is used, the number of flexible connectors  32  used, the amount of current running through the junction assembly  30 , the type and temperature of coolant used, and the like. For example, if used with an air-cooled generator having about 20,000 to about 30,000 amps of current running through the junction assembly  30 , a suitable volume is about 0.5 cubic foot to about 2 cubic feet. 
     The casing  42  can be made of a rigid or semi rigid insulating material such as fiberglass, glass, combinations thereof and the like to withstand the vibration displacement of about 20 mils during each of several million cycles that the junction assembly  30  experiences and to withstand the typical generator temperatures of about 120° F. However, the casing  42  can be made of a variety of other materials to withstand such vibration and temperature, such as metals, resins, plastics and the like. 
     FIG. 3 shows another embodiment of the present invention. In this embodiment, the junction  34  has a generally compact or condensed shape (as opposed to elongated) to assist in dispersing electrical current more evenly along the entire shape of the junction  34 , thereby addressing AC current crowding and junction assembly vibration. The flexible connectors  32  have a solid portion  64  and flexible wire strand portion  62 . The flexible connectors are arranged in a row-and-column pattern within channels  46  (or within individual slots, etc.) within this overall shape. The channels  46  form columns (e.g. C 1 -C 6 ) extending in the lateral (Y—Y) direction and the flexible connectors  32  in similar locations within different columns form rows (e.g. R 1 ) extending in the longitudinal (X—X) direction. 
     As exemplified, a pair of junctions  34  having a plurality of channels  46  (e.g.  2 - 20 , 6 illustrated) is shown securing a plurality of flexible connectors  32  (e.g.  2 - 50 , 4 illustrated) to form a junction assembly  30 . One junction  34  is adapted to connect with the parallel rings  20  and one junction  34  is adapted to connect with the main lead  22 . Two flexible connectors  32  are shown positioned within the outermost channel columns C 1 , C 6  of the junctions  34 , and two flexible connectors  32  are secured to the junctions  34  by a bolt  52  that passes through holes  50  in the junctions  34  and a nut  54 . Inlets  36  and outlets  38  are arranges on the junctions  34 , as explained above. A casing  42  is arranged around the inlets  36  and outlets  38 , as explained above. 
     FIG. 4 shows the casing  42  having a generally square or rectangular shape, an outlet  38 , and a pair of flexible connectors  32 . A pressure seal  56  is shown as an O-ring or notch to help retain and/or relieve pressure on the walls  58  of the casing  42 . 
     FIG. 5 shows the casing  42  having a generally tubular shape, with two radially extending rows of flexible connectors  32  and a central integral inlet-outlet  60 . One skilled in the art will recognize that any number of radially extending rows can be used. 
     Although this invention has been described in terms of certain exemplary uses, preferred embodiments, and possible modifications thereto, other uses, embodiments and possible modifications apparent to those of ordinary skill in the art are also within the spirit and scope of this invention. It is also understood that various aspects of one or more features of this invention can be used or interchanged with various aspects of one or more other features of this invention. Accordingly, the scope of the invention is intended to be defined only by the claims that follow.