AU2006202973B2 - Electrical link disconnect device - Google Patents

Description

S&F Ref: 772045 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address Cable Accessories (Australia) Pty. Ltd., of Applicant: an Australian company, ACN 002 184 616, of 26 Derby Street, Silverwater, New South Wales, 2128, Australia Actual Inventor(s): Bruce James Ogden Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Electrical link disconnect device Associated Provisional Application Details: [33] Country: [31] Appl'n No(s): [32] Application Date: AU 2005903751 14 Jul 2005 The following statement is a full description of this invention, including the best method of performing it known to me/us:- ELECTRICAL LINK DISCONNECT DEVICE Field of the Invention The present invention relates to the field of electrical power distribution, and in particular relates to an electrical link disconnect device. 5 Background of the Invention Underground mains power cables, utilised for residential and commercial power distribution, are buried within the ground and have their ends extending up through the ground surface where they are terminated in distribution units, from where service cables that distribute power to individual residential or commercial properties are joined. There 10 is at times a need to disconnect sections of the electrical distribution system whilst the system is under electrical load. For example, it may be necessary to disconnect a section of the service side of the system servicing a group of properties to perform some form of maintenance or to install further service cables to that group of properties. Alternatively, it may be necessary to isolate one transformer providing mains electrical power supply to i5 a section of the system, whilst allowing another nearby transformer to provide power to that section. In one current system, individual cable terminals are linked by copper or brass bus bars that are connected to the terminals by spring loaded conductive links. Disconnecting these bus bars requires specific tooling and particular care given the live nature of the 20 system. In another proposed system, a link disconnect device utilises two spring loaded conductive plates with a cam mechanism located therebetween. The cam mechanism is operated by a separate key to apply pressure to the opposing conductive plates, driving them into a frictionally locked engagement with the walls of recesses formed in the cable 25 terminals to be linked. The link disconnect device is unlocked by further operation of the cam via the key, removing the pressure applied to the conductive plates, thereby allowing the device to be removed utilising the key as a handle. This earlier proposed link disconnect device is, however, relatively complicated in construction and requires the separate key to enable its use. 30 Object of the Invention It is the object of the present invention to overcome at least one of the above disadvantages, or at least to provide a suitable alternative.

2 Summary of the Invention There is disclosed herein an electrical link disconnect device for connecting two electrical cable terminals each having opposing conductive surfaces, said device comprising: 5 a housing; a first conductive element mounted in said housing; a second conductive element mounted in said housing and opposing said first conductive element; and a locking element hingedly connected to said housing and operable between an 1o unlocking position and a locking position at which said locking element is wedged between said first conductive element and said second conductive element, driving said first conductive element and said second conductive element apart for forcibly engaging said first conductive element and said second conductive element with respective opposing conductive surfaces of each of two electrical terminals. 15 Typically, each of said first conductive element and said second conductive element is in the form of a metallic plate. Typically, said housing is formed of a non-conductive material. Typically, said device further comprises at least one compression spring separating said first conductive element and said second conductive element. 20 Typically, said locking element has a tapered operative leading edge. Said locking element may comprise a blade portion including said tapered operative leading edge. Said locking element may be provided with a detent associated with a cooperating detent on said housing for retaining said locking element in said locking position. 25 There is further disclosed herein an electrical connection comprising: a first electrical cable terminal having a first pair of opposing conductive surfaces; a second electrical cable terminal having a second pair of opposing conductive surfaces; and an electrical link disconnect device as defined above extending between said first 30 electrical cable terminal and said second electrical cable terminal, said locking element being in said locking position forcibly engaging said first conductive element with one said conductive surface of said first pair of opposing conductive surfaces and one said conductive surface of said second pair of opposing conductive surfaces and further forcibly engaging said second conductive element with the other said conductive surface 3 of said first pair of opposing conductive surfaces and the other said conductive surface of said second pair of opposing conductive surfaces. There is still further disclosed herein a method of forming an electrical connection comprising the steps of: 5 locating an electrical link disconnect device as defined above so as to extend between a first electrical cable terminal and a second electrical cable terminal with said first conductive element located adjacent a first conductive surface of each of said first electrical cable terminal and said second electrical cable terminal and said second conductive element located adjacent a second conductive surface of each of said first to electrical cable terminal and said second electrical cable terminal, said second conductive surface of each of said first electrical cable terminal and said second electrical cable terminal opposing said first conductive surface of the respective said electrical cable terminal; and pivoting said locking element into said locking position so as to drive said first 15 conductive element and said second conductive element apart into forced engagement with respective said adjacent conductive surfaces of said first electrical cable terminal and said second electrical cable terminal. Brief Description of the Drawings A preferred form of the present invention will now be described by way of example 20 with reference to the accompanying drawings wherein: Figure 1 is a side elevation view of a link disconnect device with the locking element in the locking position. Figure 2 is a cross sectional view of the link disconnect device of Figure 1 taken at cross section 2-2. 25 Figure 3 is a side elevation view of the link disconnect device of Figure 1 with the locking element in the unlocking position. Figure 4 is a perspective view of the locking element of the link disconnect device of Figure 1. Figure 5 is a perspective view of the housing of the link disconnect device of Figure 30 1. Figure 6 is an exploded view of the hinge connection of the link disconnect device of Figure 1. Figure 7 is a perspective view of a cable terminal lug suitable for use with the link disconnect device of Figure 1.

4 Figure 8 is a front elevation view of an electrical distribution connection utilising the link disconnect device of Figure 1 and cable terminal lug of Figure 7. Figure 9 is a plan view of the electrical distribution connection of Figure 8. Detailed Description of the Preferred Embodiments 5 Referring particularly to Figures 1 to 3, an electrical disconnect link device I comprises a housing 2, a first conductive element 3, a second conductive element 4 and a locking element 5. The first and second conductive elements 3, 4 are here in the form of metallic plates, typically formed of tin plated copper or some other form of conductive metallic 10 material. The first and second conductive plates here have a thickness of approximately 3 mm. The first and second conductive plates 3, 4 are mounted in the housing 2 in an opposing, parallel relationship with a gap 6 therebetween. The first and second plates 3, 4 extend between opposing longitudinal ends 7, 8 of the housing, adjacent to respective open lateral sides 9, 10 of the housing. is The locking element 5 is hingedly connected to the housing 2 by way of a hinge 11 located at the top 12 of the housing 2 adjacent the first longitudinal end 7 of the housing 2 and is operable between a locking position, as depicted in Figure 1, and an unlocking position, as depicted in Figure 3. In the locking position, the operative portion 13 of the locking element 5 is wedged in the gap 6 between the first and second conductive plates 20 3, 4, driving the first and second conductive plates 3, 4 apart. In the unlocking position, the operative portion 13 of the locking element 5 is located above the housing 2, away from the first and second conductive plates 3, 4. The locking element 5, separately depicted in Figure 4, is integrally formed of a glass reinforced nylon material. The locking element 5 has an elongate lever portion 14 25 from which depends the operative portion 13. A hinge aperture 15 is located at one end of the lever portion 14, and an enlarged ring 16 is located at the opposing end to receive the index finger of a user when operating the locking element 5. The operative portion 13 is in the form of a blade having a thickness of approximately 14 mm. The leading operative edge 13a of the blade 13 is tapered to assist in locating the blade 13 between the first and 30 second conductive plates 3, 4 and gradually driving them apart as the locking element is pivoted toward the locking position wedged between the first and second conductive plates 3, 4. The lever portion 14 of the locking element is further provided with a detent 17, here in the form of a bulbous protrusion or knob, on each opposing side to cooperate 5 with corresponding detents, in the forms of recesses 29 provided in the housing (discussed below). Referring to Figure 5, the housing 2 is formed of a non-conductive material, here a fibre reinforced nylon moulding. The housing 2 includes an upright plate portion 18 5 having a thickness of approximately 10 mm (being narrower than the blade 13 of the locking element 5) and extending along the centre of the housing between the longitudinal ends 7, 8. The plate portion 18 includes a central cut-out 19 extending through its thickness and opening to the top 12 of the housing for receipt of the blade 13 of the locking element 5. 10 Spring apertures 20 extend through the thickness of the plate portion 18 at either end of the cut-out. The spring apertures 20 receive compression springs that have their opposing ends bearing against the first and second conductive plates 3, 4, so as to maintain the appropriate gap 6 between the first and second conductive plates 3, 4 for receipt of the locking element blade 13. is Lower webs 21 laterally extend from the bottom of each opposing side of the plate portion 18, with upwardly projecting flanges 22 extending from the lower webs 21. The plate portion 18, lower webs 21 and upwardly projecting flanges 22 define lower grooves 23 for receipt of the lower edge of each of the first and second conductive plates 3, 4. The lower grooves have a thickness of approximately 5 mm, allowing lateral displacement of 20 the 3 mm thick first and second conductive plates 3, 4 as the locking element 5 is pivoted towards the locking position. The lower webs 21 and upwardly projecting flanges 22 only extend part way along the central portion of the length of the housing 2, exposing the lower end portions of the outwardly facing surfaces of the first and second conductive plates 3, 4 for electrical contact with opposing conductive surfaces of a cable terminal as 25 will be discussed below. Upper webs 24 laterally extend from the top of each opposing side of the plate portion 18, with both upwardly and downwardly projecting flanges 25, 26 extending from the upper webs 21. The plate portion 18, upper webs 24 and downwardly projecting flanges 26 define upper grooves 27 for receipt of the upper edge of each of the first and 30 second conductive plates 3, 4. The upper grooves 27 also have a thickness of approximately 5 mm, allowing lateral displacement of the first and second conductive plates 3, 4. The upper webs 24, upwardly projecting flanges 25 and downwardly projecting flanges 26 here extend between the longitudinal ends 7, 8 of the housing.

6 The upper webs 24 and associated upwardly projecting flanges 25 define a slot 28 for receipt of the lever portion 14 of the locking element 5. Recesses 29 are formed on the inner faces of the upwardly projecting flanges 25 for captively receiving the bulbous protrusions 17 formed on the lever portion 13 of the locking element discussed above, 5 allowing the locking element 5 to be retained in the locking position. Recessed hinge apertures 30 are located in each upwardly projecting flange 25 for receipt of a hinge pin 31 as depicted in Figure 6. The hinge pin 31 passes through the hinge apertures 30 of the housing and the corresponding hinge aperture 15 of the locking element 5, and is secured in place by way of a threaded fastener 32. 10 The link disconnect device 1 may be utilised with any cable terminal provided with opposing conductive faces defining a recess for receipt of each longitudinal end portion of the link disconnect device 1, with the opposing conductive faces spaced so as to be forcibly engaged by the first and second conductive plates 3, 4 of the link disconnect device 1. is An example of a particularly suitable cable terminal is a cable terminal lug disclosed in co-pending Australian divisional patent application filed on 14 July 2005 in the name of the present applicant and entitled "A cable terminal lug" as a divisional of application no. 200420141, the disclosure of which divisional application is incorporated herein by cross-reference. Such a cable terminal lug 100 is depicted in Figure 7. The 20 cable terminal lug 100 has a barrel 101 defining a first tunnel 103 opening onto the lower end face of the lug 100. A palm 102 extends from the barrel 101 and a link disconnect device mounting portion 140 extends from the palm 102 to the top face of the cable terminal lug 100. The first tunnel 103 is sized to receive a mains cable core strand which is secured in the first tunnel 103 by way of shear head fasteners 111, 119 extending into 25 the first tunnel 103 by way of threaded apertures 110, 118 in the wall of the barrel 101. The palm 102 defines opposing generally flat faces 104, 105 and a bus bar mounting aperture 109 extending therebetween. The palm 102 is suitable for mounting a bus bar for connecting two opposing cable terminal lugs 100 with a fastener extending through the mounting apertures 109 of the two opposing cable terminal lugs 100. Second 30 and third tunnels 112, 115 extend into the palm 102 for receiving service or earth cables, with the service or earth cables being secured within the second or third tunnels 112, 115 by way of grub screws 114, 117, 121 and 123 threadingly received in threaded apertures 113, 116, 120 and 122 that intersect with the second and third tunnels 112, 115.

7 The link disconnect device mounting portion 140 defines a mounting recess 141. The mounting recess 141 has an opening 142 that extends along the top end face of the cable terminal lug 100 and an adjacent lateral side of the mounting portion 140. The recess 141 is defined by a rear wall 143 and first and second opposing side walls 144, 5 145. The first and second side walls 144, 145 are each divided into primary and secondary side wall surfaces 144a, 145a and 144b, 145b. The side wall primary surfaces 144a, 145a meet the recess rear wall 143 whilst the side wall secondary surfaces 144b, 145b meet the opening 141 at the lateral side of the mounting portion 140. The opposing side wall primary surfaces 144a, 145a are separated by a distance slightly less than the 1o combined thicknesses of the first and second conductive elements 3, 4 and the locking element blade 13 of the link disconnect device 1. This provides an interference fit when the link disconnect device 1 is located in the recess 141 with one of its longitudinal ends 7, 8 abutting the recess rear wall 143 and the locking element 5 in the locking position, forcibly engaging the first and second conductive elements 3, 4 with the opposing side 15 wall primary surfaces 144a, 145a, thereby locking the link disconnect device 1 in electrical contact with the cable terminal lug 100. The secondary side wall surfaces 144b, 145b are separated by a greater distance designed to accommodate the upwardly projecting flanges 22 of the link disconnect device housing 2. An electrical distribution connection between two cable terminal lugs 100 utilising 20 a link disconnect device I is depicted in Figures 8 and 9. The two cable terminal lugs 100 are physically connected utilising an insulated bus bar 150 secured to the palms 102 of the cable terminal lugs 100 by way of a fastener 151 extending through the bus bar mounting apertures 109 of each cable terminal lug 100. The bus bar 150 thus provides a physical connection, but no electrical connection between the cable terminal lugs 100. 25 A link disconnect device I is then located so as to extend between the cable terminal lugs 100, specifically located with each longitudinal end 7, 8 of the link disconnect device 1 positioned in the mounting recess 141 of the corresponding cable terminal lug 100 with the longitudinal ends 7, 8 abutting the corresponding recess rear wall 143. The locking element 5 of the link disconnect device 1 is then forced into the 30 locking position, forcing the first and second conductive elements 3, 4 into forced engagement with the primary side wall surfaces 144a, 145a of the recess 141 in each of the cable terminal lugs 100. A secure electrical connection is thus provided between the cable terminal lugs 100. The cable terminal lugs 100 can then be readily electrically 8 disconnected by pivoting the locking element 5 to the unlocking position and removing the link disconnect device 1 from the cable terminal lugs 100 as required. Three cable terminal lugs can also be interconnected utilizing two disconnect devices by providing a broader link disconnect device mounting portion on one cable s terminal lug with two recesses as described above located side by side. A link disconnect device can then be located in each of these recesses, and extending to the single recess of two separate cable terminal lugs. Another example of a cable terminal that may be utilised with the link disconnect device is the cable connection block disclosed in International Patent Publication No. WO 10 99/03180.

Claims (12)

1. An electrical link disconnect device for connecting two electrical cable terminals each having opposing conductive surfaces, said device comprising: a housing; 5 a first conductive element mounted in said housing; a second conductive element mounted in said housing and opposing said first conductive element; and a locking element hingedly connected to said housing and operable between an unlocking position and a locking position at which said locking element is wedged 1o between said first conductive element and said second conductive element, driving said first conductive element and said second conductive element apart for forcibly engaging said first conductive element and said second conductive element with respective opposing conductive surfaces of each of two electrical terminals. is

2. The device of claim 1 wherein each of said first conductive element and said second conductive element is in the form of a metallic plate.

3. The device of either one of claims I and 2 wherein said housing is formed of a non conductive material. 20

4. The device of any one of claims I to 3 further comprising at least one compression spring separating said first conductive element and said second conductive element.

5. The device of any one of claims I to 4 wherein said locking element has a tapered 25 operative leading edge.

6. The device of claim 5 wherein said locking element comprises a blade portion including said tapered operative leading edge. 30

7. The device of any one of claims I to 6 wherein said locking element is provided with a detent associated with a cooperating detent on said housing for retaining said locking element in said locking position. 10

8. An electrical connection comprising: a first electrical cable terminal having a first pair of opposing conductive surfaces; a second electrical cable terminal having a second pair of opposing conductive surfaces; and 5 an electrical link disconnect device as defined in any one of claims I to 7 extending between said first electrical cable terminal and said second electrical cable terminal, said locking element being in said locking position forcibly engaging said first conductive element with one said conductive surface of said first pair of opposing conductive surfaces and one said conductive surface of said second pair of opposing conductive io surfaces and further forcibly engaging said second conductive element with the other said conductive surface of said first pair of opposing conductive surfaces and the other said conductive surface of said second pair of opposing conductive surfaces.

9. A method of forming an electrical connection comprising the steps of: 15 locating an electrical link disconnect device as defined in any one of claims 1 to 7 so as to extend between a first electrical cable terminal and a second electrical cable terminal with said first conductive element located adjacent a first conductive surface of each of said first electrical cable terminal and said second electrical cable terminal and said second conductive element located adjacent a second conductive surface of each of 20 said first electrical cable terminal and said second electrical cable terminal, said second conductive surface of each of said first electrical cable terminal and said second electrical cable terminal opposing said first conductive surface of the respective said electrical cable terminal; and pivoting said locking element into said locking position so as to drive said first 25 conductive element and said second conductive element apart into forced engagement with respective said adjacent conductive surfaces of said first electrical cable terminal and said second electrical cable terminal.

10. An electrical link disconnect device substantially as hereinbefore described with 30 reference to the accompanying drawings. I1

11. An electrical connection substantially as hereinbefore described with reference to the accompanying drawings. Dated

12 July, 2006 Cable Accessories (Australia) Pty. Ltd. Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON