ELECTRIC CONNECTION

Abstract: An electrical interconnection arrangement for connecting together two pieces of electrical equipment, comprising: (a) a first connection component (110) comprising a first elongate conductive member (114) which in use is at a relatively high voltage, enclosed within insulating material (116) and protruding at one end beyond an end surface thereof, the other end (120) of the first member (110) being arranged for electrical connection with one of the pieces of electrical equipment, wherein said one end of the first conductive member (114) has an enlarged radiussed region within the insulating material (116) adjacent the protruding portion (118) thereby to provide electrical stress relief at the exposed surface of the insulating material, and (b) a second connection component (112) comprising a second elongate conductive member (126) enclosed within insulating material (128) and having a socket (130) exposed at an end surface thereof for receiving the protruding end (118) of the first conductive member (114), the other end (132) of the second member (112) being arranged for electrical connection with the other of the pieces of electrical equipment; wherein a respective conductive layer (122, 134) extends over the surface of the insulating material (116, 128) of each connection component at its said one end and extends therealong towards it other end, thereby to provide electrical screening, which in use is substantially at earth potential, at said one end region of the component, each conductive layer terminating in respective first and second connection portions at respective one ends.

Description: ELECT IC CONNECTION This invention relates to electrical connections and in particular to an electrical interconnection arrangement for making an electrical connection between at least one electrical cable and another piece of electrical equipment, which may be another cable, or may be a bushing of electrical switchgear or a transformer, for example. The invention is particularly advantageous for use at rated voltages of lkV and above, and where the equipment is electrically screened. Furthermore, when used for connecting cables together, the invention is particularly advantageous for the formation of branch joints, but is also applicable to in-line joints. Notwithstanding the above, and for ease of exemplification only, the invention will be further described mainly with reference to the formation of a branch joint Arrangements for forming branch joints are many and varied. EP-B-0070696 discloses a simple cable jointing connector comprising a solid electrically insulating body that encloses a plurality of bus bar conductors whose extremities project therefrom within extension insulators, for connection to conductors of cores of respective cables. Each connection is made by bolting a lug of the cable conductor to die extremity of the bus bar, and is then insulated by a sleeve, that is preferably heat shrinkable. The cables are physically isolated from each other, so that interconnection can be made between cables that would otherwise not be compatible physically and/or chemically, for example by being of different size, configuration or material. In this context it is mentioned that one common type of cable (paper-lead) is oil-filled and another (polymeric) has material that is susceptible to damage when contacted by oil. A disadvantage of this connector is that it is not electrically screened. Furthermore, when heat-shrinkable insulating sleeves are used to insulate the connection to the -4- material and are electrically connected to the conductive layers by electrical stress control arrangements, such as a layer of material, preferably polymeric, having stress control characteristics. In this aspect, the invention is particularly suitable for forming an in-line connection between two cables, but it may also be used, for example, in connecting one cable to a bushing. The invention is however also suitable for more versatile applications. Thus, in accordance with a second aspect of the present invention, there is provided an electrical interconnection arrangement comprising : (a) a first elongate, connection component comprising (i) a conductive member enclosed within insulating material and protruding from one end thereof, the other end being arranged for electrical connection to a conductor of a first piece of electrical equipment, for example, an electric cable, and (ϋ) a conductive layer extending over die surface of the insulating material at said one end and extending therealong towards d e otiier end, thereby to provide electrical screening at one end region of die component, said conductive layer terminating in a connection portion at said one end; and (b) a second connection component comprising a body of electrically insulating material enclosing (i) an electrically conductive socket arranged to be electrically connected to other electrical equipment, and to receive and make electrical connection witii the protruding end of die conductive member of die first connection component and (ϋ) an electrically conductive structure located within the insulating body, spaced from and encircling the socket witiiin and at a surface of the insulating body to provide an external connection portion, whereby on insertion of the conductive member of die first connection component into the socket of the second conduction component so as, in use, electrically to interconnect die electric cable to the otiier electrical equipment, the connection portions are arranged to co-operate to form an electrical connection therebetween. various constructions, sizes and configurations, that is relatively easy to assemble and that can conveniendy be dis-assembled if necessary. In accordance witii a first aspect of the present invention, there is provided an electrical interconnection arrangement for connecting together two pieces of electrical equipment, at least one of which may be an electrical cable, comprising : (a) a first connection component comprising a first elongate conductive member, which in use is at a relatively high voltage, enclosed wiύiin insulating material and protruding at one end beyond an end surface thereof, die other end of die first member being arranged for electrical connection witii one of the pieces of electrical equipment, wherein said one end of die first conductive member has an enlarged radiussed region within the insulating material adjacent the protruding portion, tiiereby to provide electrical stress relief at the exposed surface of the insulating material, and (b) a second connection component comprising a second elongate conductive member enclosed within insulating material and having a socket exposed at an end surface thereof for receiving the protruding end of die first conductive member, the other end of the second member being arranged for electrical connection wiui the other of the pieces of electrical equipment; wherein a respective conductive layer extends over the surface of the insulating material of each connection component at its said one end and extends therealong towards its other end, thereby to provide electrical screening, which in use is substantially at earth potential, at said one end region of the component, each conductive layer terminating in respective first and second connection portions at respective one ends. Thus, when the first and second conductive members interengage, to produce high voltage electrical interconnection between the two pieces of electrical equipment, the first and second connection portions also interengage, and can be secured togetiier if necessary, to provide earthed electrical screening of die interconnection. Advantageously, die conductive members are, direcdy or indirectiy, exposed at their otiier ends, proximate the electrical equipment beyond their respective insulating -6- Advantageously, the protruding conductive member, for example said one end of the conductive member of the first connection component, has an enlarged radiussed region within the insulating material adjacent the protruding portion, thereby to provide electrical stress relief at die interface of the two connection components. Furthermore, tiiat part of the conductive structure of die second connection component disposed within the insulating body preferably has radiussed edges, also to provide electrical stress relief at die interface of die two connection components. The presence of either, and preferably both, of these stress relief means thus not only reduces die electrical stress within the insulation of the respective connection component but also at die interface between the components. The radiussing may be achieved by die provision of a smooth toroidal configuration around die high voltage terminals witiiin the respective insulating medium. The optimum radius of curvature needed, and die optimum distance away from the exposed surface at the interface, will depend on the electrical stress, and tiius on die operating voltage, and can be determined from theory and experiment for any particular configuration. The reduction in stress has the practical advantage tiiat the surface spacing between die conductive part at high voltage, that is to say the conductive member of d e first component and die socket of the second component, and die screening parts, that is to say die conductive layer of die first component and die exposed portion of the conductive structure of the second component can be less than it would otherwise have to be in order to prevent arcing or excessive leakage current flow therebetween. A more compact interconnection arrangement can thus be achieved. Advantageously, in order to provide electrical continuity of the shielding between the first and second connection components, each connection portion comprises a mating flange, and the arrangement comprises clamping means to urge and to secure the flanges together, diereby to ensure electrical and mechanical connection between the or each first connection component and the second connection Although as preferred and as set out for this aspect of the invention the first, elongate, connecuon component provides a protruding conductive member, and the conductive socket is provided within the body of electrically insulating material of the second connection component it is to be understood that alternatively the protruding member may extend from the second connection component and the socket may be provided on die first connection component. The arrangement modified in this way, however, is not as compact as die former arrangement. Hereinafter for convenience, reference will be mainly made to further features of the former arrangement but it is to be understood tiiat they are applicable, with appropriate modification where necessary, also to the latter, mirror-image arrangement The connection between the two pieces of electrical equipment is thus completely electrically screened. Although, as set out above, die other electrical equipment may be another electrical cable, and the connection may be an in-line joint, the invention is applicable to other configurations. For example, die second connection component may be a bushing, or otherwise may form part of equipment such as switchgear, a fuse or otiier form of circuit interrupter such as a vacuum chamber or an SF6 gas botde, or a transformer, to which one or more cables may be attached. In general, an electrical component, for example a circuit interrupter, may be connected intermediate die two connection components of the invention. When a cable is to be connected to one of die connection components, the connection portion, which may be a socket fitted witii a shear head bolt will be suitably shaped to receive the conductor, which may be circular or sector shaped for example. Furthermore, the arrangement may be used with any construction of cable, having any type of insulating material, polymeric or oil-impregnated paper, since the termination of the cable can be effected independendy of its connection to the arrangement. With oil-impregnated insulation, for example, the termination may include an oil barrier such as a suitable heat-shrinkable tubing. -8- have sockets to provide for connection to two main cable lengths and up to three branch cables. Two, or more, of the multi-socketed second connection components of the second aspect of die invention may be ganged together, that is to say they may be physically and electrically direcdy connected together, to provide for a larger plurality of connections to respective first connection members. The interface between the or each first connection element and die second connection element should be such as substantially to avoid entrapment of air. To this end, d e hardness of die abutting insulating materials can be chosen to suit, and/or a sealant, for example a gel, may be provided as part of one or die other component or of both components, or may be provided separately at the interface. Alternatively or additionally, the mating surfaces may be curved and have slighdy different curvature such that on bringing d em togedier air is exuded. The curvature of the interface assists in disconnection, in tiiat separation of die two components takes place in a peeling mode ratiier than a shearing mode, witii the consequential reduction in force needed. Although it is preferred that boti abutting surfaces are curved, and are of slighdy different curvature, it is envisaged that only one may be curved whilst the other is planar, and also tiiat both surfaces may be planar. The interface may be convoluted so as to increase the creepage padi lengtii for any flow of current between the high voltage conductors and the earthed screening conductors. The arrangement advantageously is such that an electric cable is connected to said otiier end of die, or a respective one of each, conductive member of a first connection component, wherein electric stress control material extends in electrical contact from the conductor of die cable to die conductive layer of die first connection component, which stress control material is enclosed by insulating material and by component. Advantageously, a seal, such as an O-ring seal, is provided between the flanges as part of the clamping means, to enhance moisture sealing of the interface. A preferred arrangement of the second aspect of the invention comprises at least one further first connection component, wherein the second connection component comprises at least one further said electrically conductive socket that is electrically connected within the insulating body to die said socket and tiiat is arranged to receive the further first connection component and wherein the electrically conductive structure extends so as to be spaced from and to encircle the further first socket within and at a surface of the insulating body so as to provide a further external connection portion for co-operating with the connection portion of die further first connection component, tiiereby electrically to interconnect the electric cable witii other electrical equipment connected to each of said first sockets. Advantageously, die insulating body is multi-faceted, preferably having six faces and being generally cubic for example, having one of said sockets and associated connection portions exposed at respective faces thereof for electrical connection to respective first connection components. Otiier shapes of multi-socketed components, including spherical are, however, also envisaged. Such an arrangement is particularly suited for use in forming branch joints. Two first connection components may be connected to respective lengths of main cable, and one or more branch cables may be connected to respective ones of otiier first connection components. The first connection components need not be identical witii each other. One type may be arranged to extend substantially linearly away from the second connection component, and would be particularly suitable, for example, for the main cable lengths and for a branch cable extending at right angles thereto. Another type may be of substantially L-shape such that its associated cable extends, for example, parallel with or perpendicularly to die main cable at a different level. The second connection component may be substantially rectilinear, for example cubic, and may -10- sensors may be included to detect and measure current. Advantageously, the sensors are non-linear active fibreoptic sensors operating substantially at earth potential, using one or more of the Faraday, Kerr, and Mach-Zehnder effects. Magnetic effect sensors using the Hall effect may also be used, involving a Hall effect integrated circuit or a LOHET. The direction of current flow, for example in the event of a short circuit to the earthed screening cage of the second connection component may be sensed by suitable coil windings, for example around the sockets, or otiier terminals, of the second connection component. As described, die arrangements of the invention are dis-connectable when there is no power supplied to die connection components. In some instances, however, it may be desirable to disconnect whilst the arrangement is still under power, and ti en precautions must be taken to avoid d e formation of an arc, or to reduce its effects. To this end, the surfaces of the conductors to be disconnected may be coated with an arc ablative material, such as Celcon or Melamine, which would be suitable for relatively low currents. By providing a suitable interconnection, male/female, component, it will be appreciated tiiat two (or more) of the second connection components may be stacked togedier, thereby conveniendy to increase the number of cables, or other electrical equipment that may be interconnected. Any suitable insulation material may be selected for the interface regions and/or die entire mass of the connection components, including, for example, epoxy resins, rubbers or elastomers, such as EPDM or silicone, of a range of hardnesses, or a diermoplastic material. Particularly if a thermoplastic material is selected, it may be advantageous to provide at its surface a layer of grease or a gel in order to improve the interfacial sealing and the dielectric strength at the interface. Such provision may also be made if other materials are selected. conductive material that is in electrical contact with the conductive material of the first connection component. Advantageously, the conductive member is solid and has a female socket at its cable connection end for receiving the conductor of the cable. It will thus be appreciated that a screened cable of any size, construction or configuration may be terminated by any suitable means on to uie otiier end of die first connection component, that is to say that end that in operation is remote from the second connection component. Heat shrink technology can be employed for such cable termination, without detracting from the ease of disassembly of the connection between one cable and another by means of the second connection component since the interconnection between ώe first and second components is made and broken by means of a pin and socket push-fit type of contact However, it is also envisaged that other technologies may be employed, i.e. without die use of heat including elastoraeric, push-on and tape technologies. When die number of pieces of equipment, such as cables, diat need to be interconnected is less than the number of sockets provided on d e second connection component the excess sockets may be closed off by closure caps. The closure cap may comprise an insulating body, a projection, that preferably is electrically conductive, extending from the cap insulation body so as mechanically to engage the socket and an electrically conductive member for electrically engaging with the conductive structure of the insulating body of the second connection component. It will be appreciated diat a socket may be fitted wid a closure cap initially or temporarily, and diat die cap may be removed at any time and replaced by a first connection component which may be attached to a cable, for example, in order to add a branch line to die power distribution system of the main cable. Advantageously, at least one of the connection components or of the closure caps comprises an external test point that is electrically, preferably capacitively, coupled to its respective terminal, when that component or cap is mounted on the connection component. As well as the detection of voltage, it is also envisaged that -12- The arrangement of the present invention, whilst being suitable for use at lower voltages, finds particular application at power distribution system voltages of 12kV, 15kV, 17.5kV. 24kV and above. Interconnection arrangements, each in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which : Figure 1 is a section through a generally cylindrical in-line cable interconnection arrangement; Figure 2 is a section through a connection component for a branching arrangement; Figure 3 is a section through one form of branch interconnection arrangement using the connection component of Figure 2; Figure 4 is an isometric view of an arrangement showing two different first connection components connected to a second connection component; Figure 5 shows an enlarged isometric view of the second connection component of Figure 4; Figure 6 is a vertical section through the arrangement of Figure 4; Figure 7 is a section along die line IV - IV of Figure 6; Since the electrically conductive structure of the second connection component is provided solely for electrical screening and stress control purposes, and is not required to be robust so as to carry any significant current, it can be made very lightweight, and is preferably a hollow structure, made for example from stainless steel, corrosion protected aluminium, bronze, or a conductive polymer. It may be provided as a moulding witiύn the insulating body, or as a foil, for example. The electrical screening of the arrangement may be provided by die spraying of suitable material or by electrodeposition. The socket of die second connection component is advantageously formed from a metal tube that is silver coated and has a multi-contact lamella for good electrical contact at high current levels. When two or more sockets are provided, die mbes may be welded togedier. It is thus seen tiiat die present invention is arranged to provide an electrical interconnection arrangement that (i) is compact (ϋ) is versatile in that it can be used with various numbers of pieces of electrical equipment e.g. cables, that are of different size, construction and configuration, (iϋ) allows a cable to be added or removed at any rime without interfering with the other cables, (iv) is electrically screened, and (v) can conveniendy be provided witii electrical stress relief in areas of high field strength. The compactness of the arrangement that results, at least in part from the electrical screening and stress relief provided, allows the physical separation between cables to be reduced, which is very advantageous when space has to be created by digging a trench in die earth for laying the cables, and when space is very much restricted such as when jointing is carried out in a manhole. Furthermore, the consequence of being able to operate with a relatively small interface at the interconnection is tiiat disconnection, both mechanically and electrically under load, is facilitated. -14- conductor of a further cable (not shown). The component 112 is also provided widi an outer conductive screening layer 134 terminating in a flange 136 at a radially- enlarged insulating portion around the socket 130. The exposed mating annular surfaces of the components 110 and 112 are curved so as to assist in die exclusion of air pockets at die interface when die pin 118 is fully mated witiiin die socket 130 and when the outer flanges 124 and 136 are in abutment. The curved insulating interface is offset from the annular interface of die flanges 124, 136 so as to avoid a direct path from outside die components 110, 112 to the inner high voltage conductor connection. Conductive layers 122 and 134, togedier widi die flanges 124, 136 provide screening of die interconnection, as described hereinafter. Advantageously, an annular clamp (not shown) can be applied around d e flanges so as to enhance the mechanical strength of the interconnection. A compact, low profile, screened and stress controlled in-line splice can thus be formed by the arrangement of Figure 1 when respective cables are connected to die sockets 120 and 132 thereof. Figures 2 and 3 show an arrangement, which uses a component similar to one of the components of Figure 1 together with a second component, suitable for making a branch joint. Figure 2 shows a section through a connection component 200 having a generally cubic insulating body 202 that has embedded tiierewithin a metal core 203 that has five pins 204 (only three of which are shown) projecting from respective curved faces 206 tiiereof. Electrical stress control of the curved insulating surfaces 206 is provided by enlarged and radiussed regions 208 of die core 203 therewidiin proximate the pins 204. The insulating body 202 also carries an integral insulating, metal screening structure having limbs 209 that terminate in external connecting flanges 210 that surround die pins 204 at each surface 206. Figure 8 is an exploded view in section of the arrangement also showing two closure caps for the second connection component, which is shown in a different orientation; Figure 9 shows in section a closure cap for a first connection component; Figure 10 shows a connection of a first connection component to a power distribution cable; Figure 11 is a section through a further pair of ganged connection components; Figure 12 is a section through a modification of die arrangement of Figures 6 to 8; and Figure 13 is a modification of the arrangement of Figure 7, incorporating sensing means. Referring to Figure 1, the interconnection a angement shows two elongate connection components 110, 112 electrically interconnected. Component 110 has a metal conductor 114 extending uierealong within insulating material 116 with a pin 118 protruding tiiere-rom at one end. At its other end, beyond die insulating material 116, the conductor 114 terminates in a socket 120 for receiving the conductor of a high voltage cable (not shown). At the pin end of die component 110, die insulation 114 is radially enlarged and carries a conductive screening layer 122 on its outer surface, die layer terminating in a radial flange 124. The conductor 114 is radially enlarged and radiussed wititin the insulation 116 adjacent die pin 118, so as to distribute electrical stress more evenly over die exposed annular end surface if the insulation 116. The component 112 has a coσesponding metal conductor 126 encased wititin insulating material 128. The conductor 126 terminates at one end in a socket 130 that receives die pin 118, and at its other end is a socket 132 for receiving the - 16- the flared insulation portion and slighdy spaced away from the end face 11, extends outwards to form, or to extend over the outer surface of, a radial annular flange 18 for connection to the adapter 6. The termination 4 is functionally similar to die termination 2, but differs structurally in that instead of being linear, it extends in a generally L-shape. Coσesponding components are denoted with a dash. As shown, the termination 4 also exemplifies a connection component mat is fitted with a capacitive test point 20. The test point 20 is embedded in the insulation 10' to dispose a conductive socket contact 22 spaced from d e conductive core 8' so as to be capacitively coupled thereto. In known manner, the test point 20 can indicate whether die associated core 8' has a voltage applied to it or not The adapter 6 has a generally cubic insulating body 30 with an identical double electrode system exposed at each of five of its faces 31. The high voltage electrode system comprises five tubes acting as sockets 32 that are welded togedier, moulded into die body 30 and exposed at faces thereof. Also embedded wititin the insulating body 30 and spaced from and extending around each socket 32, tiiere is a conductive cage structure 34, that forms an earthed, screening and electrical stress relief electrode system. The arms 35 defining die cage are radiussed so as to alleviate electrical stress around the sockets 32, and at d e faces 31. The conductive structure 34 extends beyond die insulating body 30 so as to dispose an annular flange 36 spaced from and encircling each socket 32 and extending away from each body face 31. The sixtii, unsocketed, face 31 of die insulating body 30 may convenientiy comprise a conductive plate 38 (Figure 6) of the cage 34. The exposed faces 31, at least in those regions that lie annularly between each high voltage socket 32 and earthing electrode ring 36, are curved for engagement widi the respective mating faces 11, 11' of the terminations 2, 4 and are of a slighdy different curvature therefrom. In Figure 3, an elongate cable connecting component 212 is shown fitted to one of the pins 204 of the component 200. Connecting component 212 differs from the component 112 of Figure 1 only in that its mating insulating surface is concave ratiier than convex, in order to mate with the convex outer surfaces 206 of the insulating body 202, and so will not be further described in detail. The flange 214 of the screening layer 216 of the cable connecting component 212 is connected to the flange 210 surrounding the associated pin 204, and thus continues the earthed electrical screening to the structure 209 of the component 200. It will be appreciated diat further cable connector components 212 will be connected to the otiier pins 204 as needed to make further cable connections. Referring to Figures 4 to 8, two first connection components, or terminations, 2, 4 and one second connection component, or adapter 6 are shown, for a 15kV power distribution system. The termination 2 is substantially linear and of substantially circular section, comprising a metal core 8 enclosed wititin insulation 10. At its forward end, die core 8 projects beyond an end face 11 of the insulation 10 to provide a pin 12 for connection to the adapter 6. Adjacent die pin 12, but still whilst encased widiin die insulation 10, the conductive core 8 is flared outwards at 13 to provide an electric stress relief configuration of general frusto-conical configuration whose base, adjacent die end face 11, is radiussed to enhance die stress relief at the face 11. The end face 11 is curved for mating with an exposed insulating surface of the adapter 6. At its rearward end, the core 8 flares outwards to a larger diameter female socket 14 beyond that end of the insulation 10. A conductive layer 16 (Figure 8) extends from approximately halfway along the outer surface of the insulation 10 towards the forward end of d e termination 2 and at - 18- right angles to it to one side or the otiier, or at any otiier angular orientation, whilst maintaining d e same electrical interconnection thereto. When there is a need for terminations to be connected only to some of the sockets of the adapter, the unused sockets are preferably closed off. Referring now to Figure 8, a first closure cap 40 for a socket 32 comprises an insulating body 42 that has a short conductive pin 44 embedded therein and projecting from a curved front surface 46 thereof. The cap 40 has an annular conductive flange 48 for mating wid an adapter flange 36, and a conductive layer 50 on its remaining outer surface. The unused socket 32 thus receives the short pin 44 and die flanges 48 and 36 are secured together by an annular clamp (not shown). Also in Figure 5, there is shown a closure cap 60 diat is modified from die cap 40 only by die provision of a test point 62, similar to the test point 20 of the termination 4, located in its insulating body 42' so as to be capacitively coupled widi its pin 44' and tiius the adapter sockets 32. Figure 9 shows a closure cap 70 suitable for mounting on the forward end of a termination 2, 4 so as to insulate its pin 12, 12', which may still be at high voltage, when the termination is not mounted on the adapter 6. The pin 70 is generally of closed cylindrical configuration, comprising an insulating body 72 with a conductive socket 74 located therewithin, and having an outer conductive surface 76 connected to an annular metal flange 78. The flange 78 is arranged to mate with a termination flange 18, 18', and to be clamped diereto, with the exposed surface of die insulation 72 mating with die termination surface 11, 11'. The interengagement of first connection components, exemplified by the terminations 2, 4, and a second connection component, exemplified by the adapter 6, has now been described. It is envisaged that one of the sockets of the second connection component may be connected to or form part of electrical equipment such as switchgear, but a more general application of the second connection component will be to interconnect several electric cables to each other, each cable being Interengagement of the termination 2, 4 and the adapter 6 takes place by inserting the termination pins 12, 12' into respective ones of the sockets 32 as push fits, with either or both of die pins and sockets being provided with multi-lamella contacts, to make the high voltage interconnection therebetween. This action brings the termination insulating surfaces 11, 11' into contact with respective faces 31, and, with the radius of curvature of the concave surface 11, 11' being greater than that of the convex surface 31, air tiierebetween will be exuded from the interface. This action also brings the termination screening flanges 18, 18' into abutment with respective ones of cage flanges 36. An annular clamp (not shown) is fitted around me mating flanges so as to ensure good mechanical and electrical interconnection tiierebetween. With die terminations 2, 4 mounted on die adapter 6, it is tiius seen that (i) a high voltage conductive path is established between the core 8, pin 12, a first socket 32, a second socket 32, pin 12' and core 8'; and (ϋ) a screening conductive path is established between the conductive layer 16, flange 18, a first flange 36, cage 34, a second flange 36, flange 18' and conductive layer 16'. Furthermore, the provision of die continuous screening layer, which is practice is maintained at earth potential (by an electrical connection, not shown), allows the outer surfaces of the interconnected terminations 2, 4 and adapter 6 to be touched in safety. Also, die electrical stress relief provided by die radiussed flared portions 13, 13' of the terminations and die radiussed cage arms 35 around die cores 8, 8' and sockets 32 respectively, allows a compact arrangement i.e. a short length, of interfaces 11, 11' and 31 to be employed. Figure 3 shows an arrangement in which only two terminations are interconnected, but it will be appreciated that a larger number, up to five, may be interconnected by the exemplified adapter 6. It will also be understood that the orientation of the terminations may be varied. For example, termination 4 may be disposed such tiiat it extends parallel to the termination 2 in the opposite direction, at -20- Figure 11 is a section through two second connection components, each of which is essentially the same as that described with reference to Figures 4 to 8 above, and which are ganged togedier to provide a larger number of possible interconnections. Thus, for convenience, where applicable like parts are indicated by like reference numerals with the addition of a suffix 'a' and 'b'. The second components, or adapters, 6a and 6b are placed side-by-side with one pair of adjacent annular screening flanges 36a, 36b in abutment and, optionally, are secured togedier by a circular clamp 300. One socket 32a of the adapter 6a is electrically connected to a socket 32b of die adapter 6b by a bus bar conductor 302. The bus bar 302 has a pin 12a, 12b at its ends for engagement with the sockets 32a, 32b respectively, die pins being flared widiin tiieir enclosing insulation 10a, 10b and being surrounded by annular screening flanges 18a, 18b. The pins 12a, 12b are integral with an intermediate metal connecting rod 304 that is contained widiin insulating material 306 that is integral widi the pin insulation 10a, 10b. The outer surface of the insulation 10a, 10b, 306 is enclosed wititin a conductive screening layer 16ab that is integral widi the flanges 18a, 18b. The five sockets 32a of the adapter 6a are thus electrically connected to the five sockets 32b of die adapter 6b by means of die pin 12a, bus bar 304 and pin 12b; and die earthed screening cage structure 35a of the adapter 6a is electrically connected to die cage structure 35b of the adapter 6b not only by the abutting flanges 36a and 36b, but also by the pin and bus bar screening comprising the flanges 18a, 18b and die conductive layer 16ab. Thus, three pieces of electrical equipment can be connected into the diree available sockets of each of the adapters 6a and 6b, and at least some of the pieces may be electric cables connected by means of first connection components such as terminations 2 or 4. It is envisaged tiiat die central opposing sockets 32a, 32b may also be direcdy interconnected by a conductor, for example a bus bar, extending tiierebetween, or alternatively they may be closed off. connected to a respective first connection component. Figure 10 exemplifies the connection of a screened 15kV polymeric cable to the termination 2. Referring to Figure 10, the cable 80 is prepared for termination or jointing in accordance widi standard procedures. Thus, the outer insulating sheath 82 is cut back to expose the underlying metal shielding layer 84, which is cut back to expose the underlying semiconductive screen layer 86, which is cut back to expose the underlying insulating layer 88, leaving an end portion 90 of the conductor exposed. Conductive paint (not shown) is applied over die small step at the exposed end of die screen 86. The conductor 90 is inserted into the female socket 14 of the core 8 of d e termination 2, and secured in place by a transverse shear-heat bolt 92. Void filling mastic (not shown) is applied around the connection of the conductor 90 to the socket 14. Prior to making this connection, two polymeric heat shrinkable tubular sleeves 94, 96 had been slid along the cable 80. The inner sleeve 94 having electrical stress control characteristics is now slid over die connection and heat is applied to it to cause it to shrink into position so as to overlap die termination outer conductive layer 16, to extend along the exposed termination insulation 10 and over the socket 14, and then to extend along the cable insulation 88, over the screen 86 and to overlap die cable shield 84. The outer tube 96 is then slid into position over the tube 94 and shrunk into position co-teπninously therewith. The tube 96 is co-extruded, d e inner component of which is insulating whilst the outer component is conducting. Continuity of the shielding across die connection of the cable 80 to die termination 2 is provided by a copper mesh strip 98 that is helically wound around die outer surface of the tube 96 along die whole of its length, and tiiat extends down onto the metal cable shield 84 at one end and down on to die termination conductive layer 16 at its other end. At each end, die mesh 98 is secured to its underlying component by a metal roll spring 100. In this way, die high voltage conductor 90 and the earthed outer shield 84 of die cable 80 are electrically connected respectively to the conductive core 8 and outer shielding layer 16 of the termination 2. -22- for indicating whether the fitting therebetween, and thus the electrical strength of the insulation interface, is of sufficient quality. It will be appreciated that with suitable modification, tiiree or more adapters may be ganged together. Figure 12 shows die termination connection component 4 of Figures 4 to 8 cooperating with another connection component 400 that is in the form of a generally cylindrical bushing of switchgear 402. The bushing 400 has an insulating body 404 diat carries a tubular conductive socket 406 diat receives the termination pin 12. The bushing insulation 404 is contained wititin an annular metal collar 408 that has a first flange 410 by which it is secured and earthed to the metal housing 412 of die switchgear 402, and a second flange 414 diat engages with the screening flange lδprime of die termination 4. Thus, the high voltage padi dirough die arrangement extends from a cable (not shown) fitted into d e termination socket 14prime, along die core 8 prime to the pin 12prime, and thence to d e bushing socket 406 that is electrically connected within the switchgear 402. The earthed screening padi extends from the termination outer conductive layer lόprirae to the flange lδprime and thence to the bushing housing 412. Figure 13 shows the arrangement of Figure 7 modified to incorporate several sensing systems. A first sensing system comprises a non-linear optic cell 500 embedded in die insulation lOprime of the termination 4 adjacent the metal core δprime. Such a sensor allows management of the electrical load of die arrangement being selected to measure voltage or current, for example using the Faraday, Kerr or Mach-Zehnder effect Signals to and from the cell 500 are guided widiin optical fibres 502 and 504 respectively. A second sensing system comprises a coil winding 510 that extends dirough the earthed cage structure 34 of the adapter 6, looping around die socket 32 and pinl2prime. By this system, the direction of current flow can be detected. Additionally or alternatively, a LOHET may be incorporated into die connector. A tiiird sensing system comprises a pressure sensor 520 located between the mating flanges 18prime and 36 of the termination 4 and the adapter 6 respectively, -24- the other end being arranged for electrical connection to the conductor of an electric cable, and (ϋ) a conductive layer extending over the surface of the insulating material at said one end and extending therealong towards the other end, tiiereby to provide electrical screening at one end region of die component, said conductive layer terminating in a connection portion at said one end; and (b) a second connection component comprising a body of electrically insulating material enclosing (i) an electrically conductive terminal arranged to be electrically connected to other electrical equipment and to make electrical connection with the terminal of d e conductive member of the first connection component, and (ϋ) an electrically conductive structure located within the insulating body, spaced from and encircling d e terminal within and at a surface of the insulating body to provide an external connection portion, whereby on engagement between the terminal of the conductive member of the first connection component and die terminal of the second conduction component so as, in use, electrically to interconnect the electric cable to die otiier electrical equipment die connection portions are arranged to co-operate to form an electrical connection therebetween. 3. An arrangement according to claim 2, wherein the terminal of the first connection component protrudes as a pin from the insulating material thereof, and wherein die terminal of d e second connection connection component comprises a socket arranged to receive the pin. 4. An arrangement according to claim 2 or claim 3, wherein said one end of die conductive member of the first connection component has an enlarged radiussed region within the insulating material adjacent the protruding portion, thereby to provide electrical stress relief at the interface of the two connection components.

Claims: -23- C ΔIM-L- 1. An electrical interconnection arrangement for connecting togedier two pieces of electrical equipment, comprising : (a) a first connection component comprising a first elongate conductive member, which in use is at a relatively high voltage, enclosed within insulating material and protruding at one end beyond an end surface thereof, the otiier end of die first member being arranged for electrical connection with one of die pieces of electrical equipment wherein said one end of die first conductive member has an enlarged radiussed region within the insulating material adjacent the protruding portion, thereby to provide electrical stress relief at the exposed surface of d e insulating material, and (b) a second connection component comprising a second elongate conductive member enclosed within insulating material and having a socket exposed at an end surface tiiereof for receiving the protruding end of the first conductive member, the other end of the second member being arranged for electrical connection with the other of die pieces of electrical equipment; wherein a respective conductive layer extends over the surface of the insulating material of each cormection component at its said one end and extends therealong towards its other end, tiiereby to provide electrical screening, which in use is substantially at earth potential, at said one end region of the component each conductive layer terminating in respective first and second connection portions at respective one ends. An electrical interconnection arrangement comprising : (a) a first, elongate, connection component comprising (i) a conductive member enclosed within insulating material and providing a terminal at one end tiiereof, -26- electrically to interconnect die electric cable widi other electrical equipment connected to each of said terminals. 10. An arrangement according to claim 9, wherein the insulating body is multi- faceted, preferably having six faces, and each of said terminals and associated connection portions are exposed at respective faces thereof for electrical connection to respective first connection components. 11. An arrangement according to claim 2 or any one of the preceding claims dependent thereon, wherein an electric cable is connected to said other end of die, or a respective one of each, first connection component, wherein electric stress control material extends in electrical contact from the conductor of die cable to the conductive layer of die first connection component which stress control material is enclosed by insulating material and by conductive material tiiat is in electrical contact with the conductive material of the first connection component 12. An arrangement according to any one of die preceding claims, wherein said other end of die or each first connection component is exposed beyond its insulating material and spaced from its outer conductive layer. 13. An arrangement according to claim 3 or any one of die preceding claims dependent uiereon, wherein the second connection component comprises a larger number of sockets than the number of first connection components, die arrangement comprising a respective closure cap for the or each excess terminal, the closure cap comprising an insulating body, a projection diat preferably is electrically conductive, extending from the cap insulation body so as mechanically to engage the socket, and an electrically conductive member for electrical engaging widi die conductive strucmre of the insulating body of the second connection component. 5. An arrangement according to claim 3 or claim 4, wherein that part of the conductive strucmre of the second connection component disposed within the insulating body has radiussed edges, thereby to provide electrical stress relief at the interface of the two connection components. 6. An arrangement according to any one of die preceding claims, wherein the or each pair of mating faces of the insulating material of the first and second connection components is curved, and is of different curvature so as, on mating, to exclude air from the interface therebetween. 7. An arrangement according to any one of de preceding claims, wherein each connection portion comprises a mating flange, and wherein die arrangement comprises clamping means to secure the flanges togedier. 8. An arrangement according to any one of die preceding claims, wherein the electrical connection between the or each first connection component and the second connection component is made as a push-fit preferably by means of a multi-laminated contact arrangement. 9. An arrangement according to claim 2 or any one of die preceding claims dependent thereon, comprising at least one further first connection component wherein the second connection component comprises at least one further said terminal, preferably a electrically conductive socket, that is electrically connected within the insulating body to d e said terminal and that is arranged to make electrical connection with the further first connection component and wherein the electrically conductive structure extends so as to be spaced from and to encircle the further terminal within and at a surface of die insulating body so as to provide a further external connection portion for co-operating with die connection portion of the further first connection component, tiiereby 14. An arrangement according to any one of the preceding claims, wherein at least one of the first connection components and/or of the closure caps comprises an external test point that is electrically, preferably capacitively, coupled to its respective socket, when that component or cap is mounted on the second connection component. 15. An arrangement according to any one of the preceding claims, wherein die or at least one of the first connection components is arranged, in use, to extend either substantially linearly or substantially in an L-shape away from the second connection component 16. An arrangement according to claim 2 or any one of the preceding claims dependent thereon, comprising at least two of said second connection connection components ganged togedier. 17. An electrical interconnection arrangement according to any one of the preceding claims, comprising means arranged to sense at least one of die voltage present therein, and die current flowing therein. 18. An electrical interconnection arrangement substantially as hereinbefore described widi reference to die accompanying drawings.

Inventors: AUMEIER WOLFRAM, BOTTCHER BODO, HARRER JOSEF, AUMEIER, WOLFRAM, BOTTCHER, BODO, HARRER, JOSEF
Applicants: AUMEIER WOLFRAM, BOTTCHER BODO, HARRER JOSEF, RAYCHEM GMBH, RAYCHEM LTD, AUMEIER, WOLFRAM, BOTTCHER, BODO, HARRER, JOSEF, RAYCHEM LIMITED
Application year: 1997
Main classification: H01R13
IPC codes: H01R4, H01R13, H01R24, H01R25, H01R31, H01R43, H02G15