Adjustable Joint for Electrical Busway

Long extents of rectangular electrical bus bars are arranged within electrical busway sections for transporting multi-phase high current electric power through industrial establishments. One example of a thermally efficient electrical busway section is described within U.S. Pat. Ser. No. 122,863 filed Nov. 19, 1987 and entitled "Thermally Efficient Power Busway Housing". This Application is incorporated herein for reference purposes and should be reviewed for its description of the arrangement of the electrical bus bars within the busway housing.

U.S. Pat. Application Ser. No. 193,000 filed May 12, 1988 entitled "Thermally Efficient Splice Joint for Electrical Distribution Busway" describes a bolted busway joint wherein the splice plates within the joint are arranged for providing accurate spacing to receive the individual bus bars of adjoining busway systems. This Application is also incorporated herein for reference purposes.

When attempting to interconnect or disconnect between a pair of existing busway sections by means of a self-contained busway joint, some expansion clearance is necessary to compensate for variations in the position of the respective busway sections. One method of compensation, such as described within U.S. Pat. No. 3,559,148, utilizes horizontal slots on the sides of the busway sections with screws attached to the joint side walls. When the joint is inserted between adjacent slotted busway sections, the screws are moved within the slots to provide the necessary adjustment.

U.S. Pat. No. 3,489,846 discloses electric busway joints having similar slotted means for allowing thermal expansion of the busway sections.

One purpose of the instant invention therefore is to provide means on adjacent busway sections, integrally formed therein, for cooperating with integrally formed means on the busway joint to provide adjustment between the adjacent busway sections and the intervening busway joint to compensate for variation between the actual total length of a busway run and the planned total length of the busway run.

The invention comprises the combination of adjacent electric busway sections and an intervening adjustable busway connecting joint (hereafter "Busway Joint"). One end of each of the electric busway side frames is integrally formed to provide outwardly extending rails aligned in the vertical plane. Both ends of the busway joint side frames are integrally formed to provide inwardly projecting channels running in the same vertical plane. The busway rails are received within the joint channels during interconnection to allow adjustable motion between the busway sections. The joint channels are slotted to indicate the position of the busway rails contained therein as well as to allow the busway insertion of a tool to assist in the adjustment of the busway rails.

FIG. 1 is a front perspective view of an adjustable electrical busway joint according to the invention;

FIG. 2 is a top perspective view in partial section of the adjustable busway joint of FIG. 1 prior to connection with a pair of adjacent busway sections;

FIG. 3 is a plan view in partial section of the busway joint of FIG. 1 with the cover removed;

FIG. 4 is a front perspective view of an alternate embodiment of the adjustable bus joint according to the invention; and

FIG. 4A is an alternate embodiment of a splice plate used within the bus joint of FIG. 4.

The busway joint 10, according to the invention is depicted in FIG. 1 attached to adjoining electrical busway sections 11 and 12. Electrically conducting bus bars 15-18 are depicted within busway section 11 between opposing side plates 14A, 14B. Similar bus bars are contained within busway section 12 and are arranged between similar opposing side plates 13A, 13B. The busway joint is fastened between the adjoining busway section by means of a thru-bolt 29 which extends through a rectangular washer 26 and a Belville washer 25. The rectangular washer is kept from rotating by means of slots 27 formed in the rectangular washer and tabs 28, extending from the face plate of the busway joint. The busway joint is enclosed at the bottom by means of a bottom cover 19 and at the top by means of a top cover 20. The top cover 20 includes slots 22 through which upstanding tabs 21 formed on the busway section side plates 13A, 13B and 14A, 14B extend. Slots 24 are similarly formed within the top cover 20 to receive corresponding bolts 23 which extend down through the slots and threadingly connect with the busway sections in a similar manner. As described in aforementioned U.S. Pat. No. 3,489,846, the slots provide expansion accommodation for thermal purposes.

The busway joint and busway sections are interconnected in the manner best seen by referring now to FIG. 2 wherein a bus joint connector module 30 such as described within the aforementioned U.S. Pat. Application Ser. No. 193,000 is indicated. As described within this Application, alternating metallic splice plates 30A are interleaved between non-metallic insulating plates 30B for connecting with the adjoining bus bars. The oval tube 35 extending through the connector module exists through the joint side frames 33, 34 by means of oval-shaped slots 36. The bus bars 15A-18A, indicated in phantom within busway section 11 between side plates 14A, 14B, are arranged for interconnection with corresponding bus bars 15B-18B arranged between the side plates 13A, 13B in the adjacent busway section 12, as also indicated in phantom. To allow for relative movement between busway section 11, busway joint 10, a vertically extending rail 31 is integrally formed at the end of each of the side plates 14A, 14B which are received within channels 32 integrally formed within the busway joint side frames 33, 34. The width of the channel recess 32A is larger than the width of the vertically extending rail 31 to allow for relative motion therebetween. When the respective busway sections are positioned within the busway joint, the busway joint side frames 33, 34 are fastened to each other and to the connector module 30 by means of a thru-bolt 42, rectangular washer 41, Belville washer 39, by means of circular slot 40 and by means of a tabbed washer 37 which contains an oval slot 38. The busway joint side plates provide excellent electrical connection with the side plates of the respective busway sections to insure good ground continuity through the joint side plates. This is essential when the side plates of the busway system provide the necessary ground conduction as described, for example, in the aforementioned U.S. Pat. Application Ser. No. 122,863. Ground continuity through the bus joint is also provided by means of the top and bottom covers 20, 19 of FIG. 1 by means of the use of non-ferrous metals such as aluminum or copper for the top and bottom covers as well as the joint side plates 33, 34 as best seen in FIG. 2. The tabbed washer 37 is fitted over the protruding end of the oval tube 35 and the tabs 37A-37D are inserted within corresponding slots 41A-41D in the rectangular washer 41 to prevent the rectangular washer from rotating during attachment between the bus way joint and the busway sections. Similar tabbed washers 37, Belville washers 39 and rectangular washers 43 are provided on the opposite side of the busway joint except that the rectangular washer 43 is threaded to engage the thru-bolt 42. When the busway joint is fastened to the busway sections, the location of the rails 31 relative to the channels 32 is determined by viewing the vertically extending rail surface 31A through the viewing slot 44 formed within the channel 32. The tool access slots 45 that are formed along the edges of the viewing slot facilitate the entry of a levering tool, such as a screwdriver, for moving the rails 31 within the channels 32. The location of the rails 31 within the channels 32 within the busway joint 10 in FIG. 1 is readily indicated by means of the surface 31A which is coated with indicia to highlight the rails when seen from the exterior of the viewing slot 44.

The assembled busway joint of FIG. 1 is depicted in FIG. 3 with the cover removed to show the location of the busway rails 31 within the bus joint channels 32 and to indicate the clearance provided within the bus joint channels by means of the width of the recesses 32A. Also indicated is the connection between the bus bars 15A-18A within the busway section 12 with the bus bars 15B-18B within busway section 13 through the connector module 30.

An alternate busway joint 46 is depicted in FIG. 4 with the connector module omitted and the bus bars within the adjoining busway sections 47, 48 all omitted for purposes of clarity. To provide for expansion with respect to the joint, a pair of tabs 51 are lanced within the side plates 49A, 49B and a similar pair of tabs 52 are lanced within the side plates 50A, 50B of the busway section 48. Complementary slots 54, 55 are formed on opposite ends of the busway joint 46 to receive the respective tabs when the busway sections are inserted within the ends of the busway joint. When the respective busway sections 47, 48 are inserted within the bus joint 46, attachment is made by means of the tabbed washer 57, Belville washer 58 and thru-bolt 60 in the same manner as described with respect to the embodiment depicted earlier with reference to FIG. 2.

An alternate splice plate 61 is depicted in FIG. 4A which consists of a metal plate 63 with an insulative epoxy coating 64 applied to both sides thereof by a selective coating process which leaves a contact area 63A devoid of such coating. This splice plate accordingly does not require alternating insulating plates such as depicted at 30B in FIG. 2. A good description of the combined insulating-splice plate is found within the aforementioned U.S. Pat. Application Ser. No. 193,000.

It has thus been shown that a simple and efficient adjustable joint can be obtained by integrally formed channels integrally formed within the busway joints. Additionally, an indicator slot is provided in the busway joint to indicate the position of the busway rails therein.