AU2016102478A4 - Electrical plug and assembly - Google Patents

Abstract

H:\stp\Interwoven\NRPortbl\DCC\STP\10288503_1.docx-14/06/16 - 24 ABSTRACT The present invention provides an electrical plug for use with a multi-core electrical cable, including a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end. The electrical plug further includes a cage assembly removably retained within the passageway proximate the second end, the cage assembly housing a plurality of electrical contacts connected to respective cores of the electrical cable. Fig. 1A 1/14 10 100 101 1 101110 102 120 Fig. 1A 100 130 102 130 130 131 120 Fig. 1 B

Description

1/14 10

100

101

102

1 101110 120 Fig. 1A

100 130 102

130 130

131 120

Fig. 1 B

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ELECTRICAL PLUG AND ASSEMBLY

Priority Documents

[0001] The present invention claims priority from Australian Provisional Application No. 2015902270 titled "ELECTRICAL PLUG AND ASSEMBLY" and filed on 15 June 2015, the content of which is hereby incorporated by reference in its entirety.

Background of the Invention

[0002] The present invention relates to an electrical plug and assembly for use with a multi core electrical cable. In a particular form, the invention relates to a restraint plug and socket used in surface and underground mining.

Description of the Prior Art

[0003] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0004] Electrical connectors such as a cable couplers and adaptors are used in the mining industry to deliver power to equipment used in surface and underground mining operations. Such connectors may be used for example to couple lengths of cable together or to connect cables to electrical switchgear and the like.

[0005] A widely used type of connector arrangement is the restrained plug and socket (or receptacle). In this arrangement, a plug is inserted into a socket and engaged with a pawl that is movable into and out of the socket by a jacking screw so as to restrain the plug within the socket. By way of example, such an arrangement may be used in an electrical three phase power system to deliver voltage up to 6.6 kilovolts (kV).

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[0006] Restrained plugs typically incorporate a one-piece moulded rubber insulator used to house electrical contacts into which phases of a multi-core cable terminate. The insulator is located in a plug body or housing. An earthing ring typically extends radially around the insulator body for contact with a nose cone or earth sleeve that is threadingly engaged with a forward end of the plug housing. Typically the rubber insulator further includes an earthed phase barrier which axially extends through the centre of the rubber insulator in order to minimise the likelihood of phase to phase faults.

[0007] The above described arrangement has several drawbacks. Firstly, it is a complex arrangement which is difficult to assemble, install and repair. Secondly, the rubber insulator is prone to damage and/or failure. Replacing a damaged insulator typically necessitates replacement of other internals of the plug body as well which is expensive and time consuming. There have also been instances of electric shocks resulting from phase to earth faults due to ineffective earth connections between the nose cone and earthing ring.

[0008] The centrally extending phase barrier typically includes a plurality of radially spaced apart legs which extend between adjacent phase conductors. In the event of an arcing incident for example, the phase barrier acts to prevent a catastrophic phase to phase fault by preferentially causing a phase to earth fault. Whilst a phase barrier of this type acts to prevent a catastrophic failure, usually the moulded interior rubber insulator encasing the phase barrier will be irreparably damaged in such an event.

[0009] It is against this background, and the problems and difficulties associated therewith, that the present invention has been developed.

Summary of the Present Invention

[0010] In one broad form the present invention seeks to provide an electrical plug for use with a multi-core electrical cable, including: a) a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end; and,

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b) a cage assembly removably retained within the passageway proximate the second end, the cage assembly housing a plurality of electrical contacts connected to respective cores of the electrical cable.

[0011] Typically, the first end of the body is removably coupled to a compression clamp that causes a portion of the cable to be clamped.

[0012] Typically, an end portion of the body proximate the second end defines a nose portion adapted to be inserted into the socket.

[0013] Typically, the nose portion is substantially cylindrical.

[0014] Typically, the nose portion extends away from a flange portion of the body in a direction of elongation of the body.

[0015] Typically, the cage assembly is located substantially within the nose portion.

[0016] Typically, the cage assembly includes a metallic cage.

[0017] Typically, the cage assembly is earthed to the body through contact between the cage and nose portion.

[0018] Typically, the cage includes a plurality of through openings that extend between a forward end and a rear end thereof, the through openings configured to each receive at least one of: a) an electrical insulator; b) an electrical insulator bushing; and, c) an electrical contact.

[0019] Typically, the cage includes an annular shoulder disposed proximate the forward end of the cage which, in use, abuts an annular locating lip disposed within the nose portion proximate the second end of the body.

[0020] Typically, the cage and nose portion include complementary locating features that act to angularly locate the cage with respect to the nose portion.

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[0021] Typically, the electrical plug further includes at least one retention element engageable with the cage assembly to thereby retain the cage assembly within the passageway of the body.

[0022] Typically, the at least one retention element engages a rear portion of the cage assembly.

[0023] Typically, the at least one retention element has a tapered end portion which engages a complementary tapered section of the rear portion of the cage assembly.

[0024] Typically, the rear portion of the cage assembly includes a groove extending at least partially around an outer periphery thereof and the at least one retention element has a tapered end portion that engages into the groove.

[0025] Typically, the groove is V-shaped.

[0026] Typically, a rear flange of the cage includes a countersunk hole and the at least one retention element has a tapered end portion that engages with the countersunk hole.

[0027] Typically, the at least one retention element extends through the body in a direction transverse to a direction of elongation of the body.

[0028] Typically, the at least one retention element is a tapered grub screw.

[0029] Typically, two tapered grub screws are used to retain the cage assembly within the passageway of the body.

[0030] Typically, the electrical plug is for use with a three-phase electrical cable.

[0031] Typically, the cable is rated up to 6.6kV.

[0032] In another broad form the present invention seeks to provide an electrical assembly, including: a) a plug, including:

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i) a unitary first body extending between a first end for receiving a first multi core electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end; and, ii) a first cage assembly removably retained within the passageway proximate the second end, the first cage assembly housing a plurality of first electrical contacts connected to respective cores of the first electrical cable; and, b) a socket, including: i) a second body having an opening for receiving the plug; and, ii) a second cage assembly removably retained at least partially within the second body, the second cage assembly housing a plurality of second electrical contacts connected to respective cores of a second multi-core electrical cable, the plurality of second electrical contacts complementary to the plurality of first electrical contacts, wherein, the plug is received in the socket to electrically interconnect the plurality of first and second electrical contacts.

[0033] Typically, an end portion of the first body proximate the second end defines a nose portion that is received in the opening of the second body.

[0034] Typically, the nose portion extends away from a flange portion of the first body in a direction of elongation of the first body.

[0035] Typically, an internal shoulder is located in the opening of the second body for abutment with the flange portion of the first body.

[0036] In another broad form the present invention seeks to provide a method of assembling an electrical plug for use with a multi-core electrical cable, the plug having a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end, the method including:

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a) terminating a plurality of cores of the electrical cable into a plurality of electrical contacts housed within a cage assembly; b) retaining the cage assembly within the passageway proximate the second end of the body; and, c) coupling a compression clamp to the body proximate the first end to cause a portion of the cable to be clamped.

[0037] Typically, the step of retaining the cage assembly includes engaging at least one retention element with the cage assembly.

[0038] Typically, the at least one retention element extends through the body and into the passageway.

[0039] Typically, the at least one retention element extends through the body in a direction transverse to a direction of elongation of the body.

[0040] Typically, the at least one retention element is a tapered grub screw which engages at least one of: a) a complementary tapered surface of a rear portion of the cage assembly; b) a groove extending at least partially around an outer periphery of a rear portion of the cage assembly; and, c) a countersunk hole formed in a rear flange of a cage of the cage assembly.

[0041] Typically, the cage assembly is inserted into the passageway through the first end of the body.

[0042] In another broad form the present invention seeks to provide a housing of an electrical plug for use with a multi-core electrical cable, including a unitary body extending between a first end configured for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end and wherein the passageway proximate the second end is further configured to receive a cage assembly housing a plurality of electrical contacts connected to respective cores of the electrical cable.

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[0043] Typically, the first end of the body is configured to be coupled to a compression clamp that causes a portion of the cable to be clamped.

[0044] Typically, an end portion of the body proximate the second end defines a nose portion adapted to be inserted into the socket.

[0045] Typically, the nose portion is substantially cylindrical.

[0046] Typically, the nose portion extends away from a flange portion of the body in a direction of elongation of the body.

Brief Description of the Drawings

[0047] An example of the present invention will now be described with reference to the accompanying drawings, in which:

[0048] Figure 1A is a perspective view of an example of an electrical plug for use with a multi-core electrical cable;

[0049] Figure 1B is a front view of the electrical plug of Figure 1A;

[0050] Figure 2 is an exploded perspective view of the electrical plug of Figure 1A;

[0051] Figure 3A is a cross-sectional side view of the electrical plug of Figure 1A;

[0052] Figure 3B is a cross-sectional side view of the electrical plug of Figure 1A taken through a tapered grub screw that retains a cage assembly within the plug body;

[0053] Figure 4 is a perspective view of an example of an electrical plug and socket assembly;

[0054] Figure 5 is an exploded perspective view of an example of a socket;

[0055] Figure 6A is a cross-sectional side view of the socket shown in Figure 5;

[0056] Figure 6B is a front view of the socket shown in Figure 5;

[0057] Figure 7A is a cross-sectional view of the electrical assembly of Figure 4 showing the plug being introduced into the socket;

[0058] Figure 7B is a cross-sectional view of the electrical assembly of Figure 4 showing the plug fully inserted and restrained in the socket;

[0059] Figures 8A to 8C provide perspective views of an example of a single wire armoured (SWA) plug shown respectively as exploded, partly assembled and fully assembled;

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[0060] Figure 9A is a perspective view of a further example of an electrical plug for use with a multi-core electrical cable;

[0061] Figure 9B is an end view of the electrical plug shown in Figure 9A;

[0062] Figure 10 is a cross-sectional side view of a portion of an electrical plug showing a further example of how the cage assembly may be retained within the plug body;

[0063] Figure 11 is a cross-sectional side view of a portion of an electrical plug showing yet a further example of how the cage assembly may be retained within the plug body; and,

[0064] Figure 12 is a flowchart of an example of a method of assembling an electrical plug for use with a multi-core electrical cable.

Detailed Description of the Preferred Embodiments

[0065] An example of an electrical plug 100 for use with a multi-core electrical cable 10 will now be described with reference to Figures 1A and 1B. Typically, the cable is a three-phase electrical power cable having three phase cores (or phase conductors) and a pilot core arranged to cut off the supply of electricity in the event of a break in an earth return path of the cable.

[0066] Typically, the cable may be used as a trailing or reeling electrical power cable for use in surface or underground mining including for example with mobile apparatus, such as excavators, draglines, stackers and reclaimers. Furthermore, the cable is typically used in low voltage systems up to 6.6 kilovolts (kV) including for example systems operating at 60, 125, 150, 300, 425 Amperes (Amps) and 660V, 1.1kV, 3.3kV and 6.6kV.

[0067] In this example, the plug 100 includes a unitary or integral body 102 extending between a first end 101 for receiving the electrical cable 10 and a second end111 configured for insertion into a socket (or receptacle). An example of such a plug is known as a restrained plug in which the plug is inserted into a socket and restrained by a pawl or similar device through actuation of a jacking screw.

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[0068] The body 102 includes a passageway (not shown) extending between the first end 101 and the second end 111. Accordingly, the body defines a hollow interior suitable for terminating an end of the cable therein.

[0069] The plug 100 further includes a cage assembly 120 removably retained within the passageway proximate the second end 111, the cage assembly 120 housing a plurality of electrical contacts 130, 131 connected to respective cores of the electrical cable 10. Whilst the electrical contacts 130, 131 could be male or female contacts, typically the plug 100 houses female electrical contacts and the mating socket houses complementary male electrical contacts such as contact pins.

[0070] The above described arrangement provides a simpler construction than known plugs in the art. In prior art arrangements, typically a forward most extension of the plug known as a nose cone or earth sleeve is provided separate to the plug body. The nose cone is typically threadingly engaged with the plug body after the cable has been terminated into the cage assembly. In other prior art arrangements, the plug body comprises a front body section and a rear body section that is mechanically fastened to the front body section after the cage assembly has been located in the front body section. In this type of arrangement, the rear body section effectively clamps or otherwise retains the cage assembly within the plug body.

[0071] The above described electrical plug having a unitary body is advantageous over the prior art for several reasons. Firstly, it is easier to manufacture a single part than multiple parts which reduces manufacturing cost and time. Further, reducing the number of body parts minimises inventory which also provides a cost saving. Assembly and repair of the plug is also made simpler by providing a unitary body arrangement. The plug is also likely to be more durable and robust in its operating environment. For example, in prior art arrangements having threaded nose cones, the threaded connection may loosen through repeated use which can cause inadequate earthing, stress on the cable and failure of the plug. A unitary or integral body eliminates the possibility of such faults.

[0072] A number of further features shall now be described with reference to Figures 2 to 3B.

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[0073] The plug 100 has a generally elongate body 102 extending between the first end 101 and the second end 111. An end portion of the body 102 proximate the second end 111 defines a nose portion 110 adapted to be inserted into the socket or receptacle. The nose portion 110 extends away from a flange portion 114 of the body 102 in a direction of elongation of the body. Typically, the nose portion 110 is substantially cylindrical as shown in Figure 2. A terminal end of the nose portion 110 may be tapered in order to ease insertion of the plug into the socket.

[0074] The body 102 is substantially hollow and defines a passageway extending between the first end 101 and the second end 111. In the example shown, the passageway includes a first section 105 extending from the first end 101 to the flange portion 114 and a second section 115 extending through the nose portion 110 of the body 102 from the flange portion 114 to the secondend 111.

[0075] In use, the electrical cable enters the plug body 102 proximate the first end 101. A portion of the cable is supported or clamped proximate the first end 101 so that the cable is restrained from moving relative to the plug body. The first end 101 of the plug body 102 is adapted to receive a compression ring 154 (also known as a gland or grommet), typically made from rubber through which the cable is passed. Accordingly, the compression ring 154 defines an opening having a diameter substantially the same as the cable diameter. The compression ring 154 is seated within the plug body 102 proximate the first end 101. For example, an end section of the body 102 proximate the first end 101 may include a radial seat or shoulder upon which the compression ring 154 is seated.

[0076] A compression clamp 150 is removably coupled to the first end 101 of the body 102 so as to exert an axial force on the compression ring 154. Typically, the compression clamp 150 is mechanically fastened to the plug body 102 by way of suitable fasteners including screws or bolts. In one example, the compression clamp 150 includes a flange having a plurality of radially spaced apart mounting lugs or eyelets that project outwardly from the flange so as to form attachment points for fastening. Fasteners extend through the mounting lugs of the compression clamp 150 and into corresponding lugs or eyelets disposed proximate

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the first end 101 of the body 102 in order to mount or couple the compression clamp 150 to the plug body 102.

[0077] As the compression clamp 150 is fastened to the body 102, an axial force is applied to the compression ring 154 in the direction of elongation of the body 102 which causes a portion of the cable to be clamped. The design of the compression ring 154 is such that an axial force applied to it is translated into a radial compression force. In this way, as the compression clamp 150 is fastened to the body 102, the compression ring 154 is urged to exert a clamping force on a portion of the cable disposed within the compression ring 154. In the example shown in Figures 2 and 3A, the compression ring 154 is sandwiched between a pair of metallic pressure washers 152 which assist in distributing the axial load from the compression clamp 150 to the compression ring 154.

[0078] In another example as shown in Figures 8A to 8C, the plug may be adapted for use with a single wire armoured (SWA) cable 20. In this example, a compression clamp 350 is coupled to a first end 301 of a plug 300 as previously described so that it exerts an axial force onto a compression ring 354 when it is fastened to the plug body 302. The compression ring 354 may be sandwiched between pressure washers 352. In this example, the plug 300 further includes a pair of split conical sections 355, 356 which are joined together around the cable so as to form a cone. A conical clamp 358 is then engaged with the split conical sections 355, 356 in order to clamp the single wire 360. In this regard, the single wire 360 is hooked around the conical clamp 358 and the conical clamp 358 is then sleeved over the split conical sections 355, 356 which sandwiches the single wire 360 between the conical clamp 358 and split conical sections 355, 356 in a tapered locking arrangement. The conical clamp 358 is fastened to the split conical sections 355, 356 and compression clamp 350 through fasteners which extend through corresponding mounting lugs or eyelets of the respective parts. In the above example, the compression clamp 350 has a flat rear surface to accommodate mounting of the split conical sections 355, 356.

[0079] Referring back to Figure 2, the cage assembly 120 shall now be described in further detail. The cage assembly 120 includes a metallic cage or barrel 121 which includes a plurality of through openings 122, 123 that extend between a forward end and a rear end

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thereof. In the example shown, the through openings 122, 123 are configured to receive respective electrical insulators 132, 133 which in turn house the electrical contacts 130, 131 to which respective cores of the cable are terminated. Insulator bushes 134, 135 are engaged into the rear of the insulators 132, 133 so as to hold the electrical contacts 130, 131 into the insulators 132, 133. A rear portion of the cage assembly in the form of an end cap or locking flange 140 has openings which engage around at least a portion of the bushes 134, 135 which, in use, protrude out from a rear face of the cage 121. A screw or similar fastener 136 longitudinally extends through the cage 121 and into the end cap 140 to fasten the cage assembly 120 together. When fastened in this manner, the end cap 140 retains the insulators 132, 133 and contacts 130, 131 within the cage 121.

[0080] The cage 121 may take several different forms and is not intended to be limited to any particular shape or configuration. In the example shown, the cage 121 has a cloverleaf sectioned outer body defining a plurality of radially spaced apart passageways that provide termination recesses for the respective cores of the cable. In other forms, the cage 121 may instead have a more general cylindrical profile without the cloverleaf sections.

[0081] As shown in Figures 3A and 3B, the cage assembly 120 is located substantially within the nose portion 110 of the body 102 proximate the second end 111. The cage 121 includes an annular shoulder portion 124 disposed proximate the forward end of the cage 121 which, in use, abuts an annular locating lip 112 disposed within the nose portion 110 proximate the second end 111 of the body 102. Abutment between the shoulder 124 and lip 112 restrains the cage assembly 120 from moving axially past the second end 111 of the body 102 which also prevents the cage assembly 120 from inadvertently being pulled out of the front of the body 102 in use.

[0082] The cage 121 and nose portion 110 may further include complementary locating features that act to angularly locate the cage 121 with respect to the nose portion 110. For example, the terminal end of the nose portion 110 may include an inwardly projecting protrusion engageable with a complementary slot or groove located on the periphery of the front face of the cage 121. In this way, the cage assembly 120 may be located in the nose portion 110 so as to have a specific angular orientation with respect to the nose portion 110.

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This ensures that each time the plug 100 is assembled, the phase and pilot conductors will be arranged in the same angular configuration with respect to the body 102 of the plug 100. This enables the plug to be readily inserted into the socket in a convenient and repeatable manner.

[0083] After the cage assembly 120 has been located in the nose portion 110 proximate the second end 111 of the body 102, at least one retention element 160 is engaged with the cage assembly 120 to thereby retain the cage assembly 120 within the passageway of the body 102. Typically, the at least one retention element 160 engages the rear portion or end cap 140 of the cage assembly 120. As best shown in Figure 3B, in one example the at least one retention element 160 includes a threaded shaft 162 having a tapered end portion 164 which engages a complementary tapered section 142 of the rear portion 140 of the cage assembly 120. In use, the at least one retention element 160 extends through the body 102 (e.g. through threaded holes 103) in a direction transverse to a direction of elongation of the body 102 so as to at least partially extend into the passageway 105.

[0084] Typically, the at least one retention element is a tapered grub screw 160 and in the example shown in Figure 2, two tapered grub screws 160 are used to retain the cage assembly 120 within the passageway of the body 102. As the grub screws 160 are screwed into threaded holes in the body 102 of the plug 100, the tapered section 164 engages with the tapered outer surface 142 of the end cap 140 which thereby exerts an axial force on the cage assembly 120 urging it towards the second end 111. The cage assembly 120 is therefore effectively sandwiched between the annular lip 112 inside the nose portion 110 proximate the second end 111 and the grub screws 160. Accordingly, the cage assembly 120 is retained or fixed in position relative to the body 102 of the plug 100 and restrained from moving axially in any direction.

[0085] The tapered grub screws 160 therefore provide a simple and convenient means of retaining the cage assembly 120 within the passageway of a unitary plug body.

[0086] The above described cage assembly arrangement is further advantageous as it ensures that the cage assembly is effectively earthed to the plug body in a reliable manner. As the cage 121 is metallic, the cage assembly 120 is able to be earthed to the body 102 through

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contact between the cage 121 and nose portion 110. Typically, the body 102 is made from any suitable metal such as stainless steel or aluminium. As the cage 121 and nose portion 110 are in continuous circumferential contact, the cage 121 is symmetrically earthed all the way around the perimeter of the cage 121 which provides a more reliable earthing connection than prior art arrangements.

[0087] A metallic cage also removes the need to have a metallic phase barrier for phase segregation. Whereas prior art arrangements provide a rubber insulator body housing the electrical contacts, the above described arrangement provides a metallic cage housing individual insulator bodies surrounding the electrical contacts. The phases are therefore physically separated by the metallic cage body which significantly reduces the likelihood of any phase to phase faults occurring. The metallic cage is also more robust and durable than the rubber insulator body which is prone to degradation and failure.

[0088] An example of an electrical assembly shall now be described with reference to Figures 4 to 7B.

[0089] In this example, the electrical assembly includes a plug 100 and a socket or receptacle 200. As previously described, the plug 100 includes a unitary first body 102 extending between a first end 101 for receiving a first multi-core electrical cable 10 and a second end 111 configured for insertion into the socket 200, the body 102 including a passageway extending between the first end 101 and the second end 111. The plug 100 further includes a first cage assembly 120 removably retained within the passageway proximate the second end 111, the first cage assembly 120 housing a plurality of first electrical contacts 130, 131 connected to respective cores of the first electrical cable 10.

[0090] The socket 200 includes a second body 202 having an opening 203 for receiving the plug 100. A second cage assembly 220 is removably retained at least partially within the second body 202, the second cage assembly 220 housing a plurality of second electrical contacts 230, 231 connected to respective cores of a second multi-core electrical cable (not shown), the plurality of second electrical contacts 230, 231 complementary to the plurality of first electrical contacts 130, 131. The plug 100 is received in the socket 200 so as to

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electrically interconnect the plurality of first and second electrical contacts 130, 131, 230, 231.

[0091] As shown in Figure 4, the socket 200 generally includes a mounting plate 210 to allow the socket 200 to be mounted to switchgear enclosures and the like. In this context, the socket 200 (or receptacle) is generally referred to as an outlet. To assist in insertion and withdrawal of the plug 100 from the socket 200, a jacking screw assembly comprising a jacking screw 242, pawl 240 and handle 245 is used. Typically, the pawl 240 is threadingly engaged with the jacking screw 242 and movable there along as the handle 245 is rotated. In use, the pawl 240 is engaged into a groove 106 of the plug body 102 such that the plug 100 is jacked or strained into the socket 200 as the handle 245 is rotated to thereby retain the plug 100 securely in the socket 200.

[0092] The socket 200 includes a cage assembly 220 consisting of a cage 221 having a plurality of through openings 222, 223 for receiving electrical contacts 230, 231. In the example shown, the electrical contacts 230, 231 are male contacts in the form of pins. Contacts 230 are phase contact pins and contact 231 is a pilot contact pin. The electrical contacts 230, 231 are disposed within respective insulators 232, 233 and held therein by insulator bushes 234, 235. The bushes 234, 235, contact pins 230, 231 and insulators 232, 233 are securely clamped into the cage 221 by a metallic star 236 which is wedged between the respective bushes 234, 235 proximate a rear surface of the cage 221.

[0093] The cage 221 further includes a forward end portion 225 in the form of an earth sleeve which in use, receives the nose portion 110 of the plug body 102. The earth sleeve 225 is generally cylindrical and may comprise a plurality of circumferentially spaced scored sections able to resiliently flex to allow easier insertion of the nose portion 110 therein.

[0094] The cage assembly 220 is mounted into the socket 200 through a rear opening 212 and retained within the socket 200 by a pair of tapered grub screws 260 (as previously described with respect to the plug) that engage into openings or notches 224 located on the cage body 221. The tapered grub screws 260 are screwed through the body 202 of the socket 200 in a direction transverse to a direction of elongation of the socket 200.

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[0095] As shown in Figure 6A, typically when the cage assembly 220 is mounted into the socket 200, a portion of the cage assembly 220 protrudes beyond a rear surface of mounting plate 210.

[0096] Figures 7A and 7B show the plug and socket disengaged and engaged respectively. When disengaged, a portion of the pawl 240 is disposed beyond a forward end of the socket 200. As the plug 100 is introduced into the socket 200, the pawl 240 is located in groove 106 formed between surfaces 107, 108 which project upward from the plug body 102. The handle 245 is then rotated in order to jack the plug 100 into the socket 200. As the handle 245 is turned the pawl 245 moves into the socket 200 along jacking screw 242 and exerts a force on surface 107 which urges the plug 100 further into the socket 200. The nose portion 110 slides into the earth sleeve 225 and the plurality of first electrical contacts 130, 131 engage with the plurality of second electrical contacts 230, 231. In the example shown, the phase contact pins 230 are received within the phase female finger contacts 130 and the pilot contact pin 231 is received within the pilot female finger contact 131.

[0097] An internal shoulder 204 is located in the opening of the socket body 202 for abutment with the flange portion 114 of the plug body 102 proximate the base of the nose portion 110. The internal shoulder 204 defines a hard stop for the plug 100 as it is being inserted into the socket 200. When the plug 100 is fully engaged in the socket 200, the flange portion 114 of the body 102 abuts the internal shoulder 204. The plug 100 is prevented from inadvertent withdrawal from the socket 200 by the jacking screw assembly which cannot slip or unwind.

[0098] Referring now to Figures 9A and 9B, there is shown a further example of an electrical plug 400 for use with a multi-core electrical cable. In this example, the plug 400 includes an integral body 402 having a nose portion 410 extending away from a flange portion 414 of the body 402 in a direction of elongation of the body, the nose portion 410 substantially housing a cage assembly 420 as previously described. In this example, the flange portion 414 radially extends away from the body 402 and has a circular or annular profile, the same as the body 402, which is substantially cylindrical in structure. In the previously described examples, the plug flange and body have had at least partially dissimilar profiles.

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[0099] In this example, a pair of retaining elements 460 (grub screws) are radially spaced apart the body 402 for insertion into bosses or protrusions 403 formed in the outer surface of the body 402. As previously described, the grub screws 460 have tapered ends which engage with complementary tapered surfaces of a rear portion of the cage assembly 420 of the plug 400 when the screws 460 are fastened into the body 402. The radial spacing and number of grub screws 460 may be variable so long as the cage assembly 420 is firmly retained within the body 402 of the plug and prevented from moving axially therein.

[0100] Whilst in the previous examples, the retaining elements engage a back surface of a rear portion or end cap of the cage assembly, other means of retaining the cage assembly may be employed.

[0101] For example, with reference to Figure 10, there is shown a portion of an example of an electrical plug 500 wherein the cage assembly 520 includes a rear portion or end cap 540 having a groove 542 (for example a V-shaped groove) extending at least partially around an outer periphery thereof and wherein at least one retention element 560 (for example grub screws) has a tapered end portion 564 that engages into the groove 542. In this way, as the grub screws 560 are screwed into threaded holes 513 in the flange 514 of the plug 500, the tapered section 564 engages with the walls of the groove 542 in the end cap 540 which thereby exerts an axial force on the cage assembly 520 urging it towards the second end 511 of the plug body 502 whereby an annular lip of the nose portion 510 abuts an annular shoulder of the cage assembly 520. As such, the cage assembly 520 is retained or fixed in position relative to the body 502 of the plug 500 and restrained from moving axially in any direction.

[0102] A further example is shown in Figure 11, in which a rear flange 625 of the cage 621 of the cage assembly 620 includes a countersunk hole 626 and wherein at least one retention element 660 has a tapered end portion 664 that engages with the countersunk hole 626. In this way, as the grub screws 660 are screwed into threaded holes 613 in the flange 614 of the plug 600, the tapered section 664 engages into the countersunk hole 626 in the rear flange 625 of the cage 621 which thereby exerts an axial force on the cage assembly 620 urging it towards the second end 611 of the plug body 602 whereby an annular lip of the nose portion

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610 abuts an annular shoulder of the cage assembly 620. As such, the cage assembly 620 is then retained or fixed in position relative to the body 602 of the plug 600 and restrained from moving axially in any direction.

[0103] A method of assembling an electrical plug for use with a multi-core electrical cable shall now be described with reference to Figure 12. In this example, the plug has a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end.

[0104] At step 700, the method includes terminating a plurality of cores of the electrical cable into a plurality of electrical contacts housed within a cage assembly. Preferably, the cage assembly includes a metallic cage housing a plurality of insulators that surround the electrical contacts.

[0100] At step 710, the method includes retaining the cage assembly within the passageway proximate the second end of the body. The cage assembly is inserted into the passageway through the first end of the body (i.e. the rear end of the plug) and located substantially in a nose portion thereof proximate the second end. Typically, the step of retaining the cage assembly includes engaging at least one retention element with the cage assembly. The at least one retention element typically extends though the body and into the passageway. In one example, the at least one retention element is a tapered grub screw which engages a rear portion or end cap of the cage assembly. The rear portion of the cage assembly is preferably also tapered so that a tapered portion of the grub screw engages a corresponding tapered section of the rear portion of the cage assembly. In this way, as the grub screw is fastened through the plug body, the tapered sections engage and progressively tighten together to effectively lock the cage assembly in the passageway of the plug body.

[0101] As described above however, alternative means of retaining the cage assembly may be used, such as by providing a V-groove around at least a portion of the outer periphery of the end cap into which the tapered grub screw is located. Alternatively, a countersunk hole

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may be provided in a rear flange of the cage into which the tapered grub screw is located in order to retain the cage assembly with respect to the plug body.

[0102] At step 720, a compression clamp is coupled to the body proximate the first end which causes a portion of the cable to be clamped. In one example, the compression clamp exerts an axial force onto a rubber compression ring disposed around the portion of the cable. The rubber compression ring in turn exerts a radial compression force to the portion of the cable which clamps the portion of the cable thereby securing or supporting it with respect to the plug body.

[0103] The above described method advantageously simplifies the assembly process. For example, whereas prior art arrangements include multi-part plug bodies which need to be fastened together to complete the assembly, the above described method eliminates this step as a consequence of the plug having a unitary or integral body.

[0104] Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

[0105] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.

Claims (1)

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   THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1) An electrical plug for use with a multi-core electrical cable, including: a) a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end; and, b) a cage assembly removably retained within the passageway proximate the second end, the cage assembly housing a plurality of electrical contacts connected to respective cores of the electrical cable. 2) An electrical plug according to claim 1, wherein the first end of the body is removably coupled to a compression clamp that causes a portion of the cable to be clamped. 3) An electrical plug according to claim 1 or claim 2, wherein an end portion of the body proximate the second end defines a nose portion adapted to be inserted into the socket. 4) An electrical plug according to claim 3, wherein the nose portion is substantially cylindrical. ) An electrical plug according to claim 3 or claim 4, wherein the nose portion extends away from a flange portion of the body in a direction of elongation of the body. 6) An electrical plug according to any one of claims 3 to 5, wherein the cage assembly is located substantially within the nose portion. 7) An electrical plug according to any one of claims 3 to 6, wherein the cage assembly includes a metallic cage. 8) An electrical plug according to claim 7, wherein the cage assembly is earthed to the body through contact between the cage and nose portion. 9) An electrical plug according to claim 7 or claim 8, wherein the cage includes a plurality of through openings that extend between a forward end and a rear end thereof, the through openings configured to each receive at least one of: a) an electrical insulator; b) an electrical insulator bushing; and, c) an electrical contact.

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   ) An electrical plug according to claim 9, wherein the cage includes an annular shoulder disposed proximate the forward end of the cage which, in use, abuts an annular locating lip disposed within the nose portion proximate the second end of the body. 11) An electrical plug according to claim 10, wherein the cage and nose portion include complementary locating features that act to angularly locate the cage with respect to the nose portion. 12) An electrical plug according to any one of the preceding claims, further including at least one retention element engageable with the cage assembly to thereby retain the cage assembly within the passageway of the body. 13) An electrical plug according to claim 12, wherein the at least one retention element engages a rear portion of the cage assembly. 14) An electrical plug according to claim 13, wherein the at least one retention element has a tapered end portion that engages a complementary tapered section of the rear portion of the cage assembly. ) An electrical plug according to 13, wherein the rear portion of the cage assembly includes a groove extending at least partially around an outer periphery thereof and wherein the at least one retention element has a tapered end portion that engages into the groove. 16) An electrical plug according to claim 15, wherein the groove is V-shaped. 17) An electrical plug according to claim 12, wherein a rear flange of the cage includes a countersunk hole and wherein the at least one retention element has a tapered end portion that engages with the countersunk hole. 18) An electrical plug according to any one of claims 12 to 17, wherein the at least one retention element extends through the body in a direction transverse to a direction of elongation of the body. 19) An electrical plug according to any one of claims 12 to 18, wherein the at least one retention element is a tapered grub screw. ) An electrical plug according to claim 19, wherein at least two tapered grub screws are used to retain the cage assembly within the passageway of the body. 21) An electrical plug according to claim 20, wherein the at least two grub screws are radially spaced about the body.

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   22) An electrical plug according to any one of the preceding claims, for use with a three phase electrical cable. 23) An electrical plug according to claim 22, wherein the cable is rated up to 6.6kV. 24) An electrical assembly, including: a) a plug, including: i) a unitary first body extending between a first end for receiving a first multi-core electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end; and ii) a first cage assembly removably retained within the passageway proximate the second end, the first cage assembly housing a plurality of first electrical contacts connected to respective cores of the first electrical cable; and, b) a socket, including: i) a second body having an opening for receiving the plug; and ii) a second cage assembly removably retained at least partially within the second body, the second cage assembly housing a plurality of second electrical contacts connected to respective cores of a second multi-core electrical cable, the plurality of second electrical contacts complementary to the plurality of first electrical contacts, wherein, the plug is received in the socket to electrically interconnect the plurality of first and second electrical contacts. ) An electrical assembly according to claim 24, wherein an end portion of the first body proximate the second end defines a nose portion that is received in the opening of the second body. 26) An electrical assembly according to claim 25, wherein the nose portion extends away from a flange portion of the first body in a direction of elongation of the first body. 27) An electrical assembly according to claim 26, wherein an internal shoulder is located in the opening of the second body for abutment with the flange portion of the first body. 28) A method of assembling an electrical plug for use with a multi-core electrical cable, the plug having a unitary body extending between a first end for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end, the method including:

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   a) terminating a plurality of cores of the electrical cable into a plurality of electrical contacts housed within a cage assembly; b) retaining the cage assembly within the passageway proximate the second end of the body;and c) coupling a compression clamp to the body proximate the first end to cause a portion of the cable to be clamped. 29) A method according to claim 28, wherein the step of retaining the cage assembly includes engaging at least one retention element with the cage assembly. ) A method according to claim 29, wherein the at least one retention element extends through the body in a direction transverse to a direction of elongation of the body. 31) A method according to claim 30, wherein the at least one retention element is a tapered grub screw which engages at least one of: a) a complementary tapered surface of a rear portion of the cage assembly; b) a groove extending at least partially around an outer periphery of a rear portion of the cage assembly; and, c) a countersunk hole formed in a rear flange of a cage of the cage assembly. 32) A method according to any one of claims 28 to 31, wherein the cage assembly is inserted into the passageway through the first end of the body. 33) A housing of an electrical plug for use with a multi-core electrical cable, including a unitary body extending between a first end configured for receiving the electrical cable and a second end configured for insertion into a socket, the body including a passageway extending between the first end and the second end and wherein the passageway proximate the second end is further configured to receive a cage assembly housing a plurality of electrical contacts connected to respective cores of the electrical cable. 34) A housing according to claim 33, wherein the first end of the body is configured to be coupled to a compression clamp that causes a portion of the cable to be clamped. ) A housing according to claim 33 or claim 34, wherein an end portion of the body proximate the second end defines a nose portion adapted to be inserted into the socket. 36) A housing according to claim 35, wherein the nose portion is substantially cylindrical. 37) A housing according to claim 35 or claim 36, wherein the nose portion extends away from a flange portion of the body in a direction of elongation of the body.

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