An apparatus for a cable for transmission of power

Abstract

An apparatus for a cable for transmission of power is provided, the cable comprising a conductive core and an earthing screen layer, the apparatus comprising a coupling assembly comprising a receiving end arranged to receive a connecting end of the cable, an earth coupling means arranged at the receiving end of the coupling assembly, and an insulating sleeve arranged at the earth coupling means such that the earth coupling means contacts the receiving end of the coupling assembly, wherein, when the cable is received by the apparatus, the earthing screen layer at the connecting end of the cable is arranged to be intermediate the earth coupling means and the receiving end of the coupling assembly. A system for electrically terminating a cable is also provided, the cable being suitable for transmission of power with voltage levels greater than or equal to 1 kV.

Description

[0001] An apparatus for a cable for transmission of power

[0002] Technical Field

[0003] The present disclosure relates to an apparatus for a cable for transmission of power. The apparatus may be a grounding or earthing apparatus, or may be a terminating apparatus.

[0004] Cables are typically used to provide an electrical connection for electrical machines. For example, in the mining or petroleum industry, large electrical machinery may be used and each cable may have to deliver power with voltage levels greater than or equal to 1 kV. The cables may comprise one or more cores and are connected using electrical connection systems including sockets, pins and thimbles. The cores typically are insulated from each other and surrounded by a conductive layer that is on earth potential. Therefore, if the cores break, individual broken cores are less likely to be in electrical contact with each other, but instead are likely to be in electrical contact with respective layers that are on earth potential. Automatic electrical earth leakage protection devices may be used. In case of electrical contact between one of the cores and one or more layers that are on earth potential, an automatic electrical earth leakage protection device can detect an earth leakage current and subsequently interrupt the supply of electricity. Therefore, melt-down of the cable, electrical arcing and the like can be avoided. However, within a plug / coupling connection (electrical device) individual cores typically are not surrounded by individual layers on earth potential but are stripped off the layer and are surrounded by a common electrical casing that is on earth potential. If individual cores are disrupted within the plug, it is more likely that the disrupted cores are in direct electrical contact with each other causing fault currents. This can have dangerous consequences especially in an environment that may contain explosive gases such as a mine.

[0005] In one aspect, there is provided an apparatus for a cable for transmission of power, the cable comprising a conductive core and an earthing screen layer, the apparatus comprising: a coupling assembly comprising a receiving end arranged to receive a connecting end of the cable; an earth coupling means arranged at the receiving end of the coupling assembly; and an insulating sleeve arranged at the earth coupling means such that the earth coupling means contacts the receiving end of the coupling assembly, and wherein, when the cable is received by the apparatus, the earthing screen layer at the connecting end of the cable is arranged to be intermediate the earth coupling means and the receiving end of the coupling assembly.

[0006] In one embodiment, when the cable is received by the apparatus, the earthing screen layer is in secure contact with the earth coupling means and the receiving end of the coupling assembly.

[0007] In one embodiment, the earth coupling means is in secure contact with the receiving end of the coupling assembly.

[0008] In one embodiment, the earth coupling means is in forced contact against the receiving end of the coupling assembly.

[0009] In one embodiment, the earthing screen layer is in forced contact with the earth coupling means and the receiving end of the coupling assembly.

[0010] The securement or force may be provided by a screw-type engagement of the insulating sleeve.

[0011] The securement or force may be provided by a snap-fit engagement of the insulating sleeve.

[0012] In one embodiment, the arrangement of the earthing screen layer at the connecting end of the cable intermediate the earth coupling means and the receiving end of the coupling assembly electrically terminates the cable onto the coupling assembly.

[0013] In one embodiment, the insulating sleeve substantially circumferentially contacts the earth coupling means against the receiving end of the coupling assembly.

[0014] In one embodiment, there are multiple points of contact between the earth coupling means and the receiving end of the coupling assembly, the multiple points of contact being circumferentially arranged.

[0015] In one embodiment, the earth coupling means comprises a conductive material. The conductive material may be a metallic material.

[0016] In one embodiment, the conductive core and earthing screen layer are coaxial. In one embodiment, the earth coupling means and the receiving end of the cylindrical connection assembly are coaxial.

[0017] The receiving end of the coupling assembly, the earth coupling means and the insulating sleeve may be substantially cylindrical.

[0018] The cable may be suitable for transmission of power with voltage levels greater than or equal to 1 kV.

[0019] The cable may be suitable for transmission of high frequency signals.

[0020] In one embodiment, the apparatus is characterised by a low impedance.

[0021] In one embodiment, the apparatus is characterised by a substantially low impedance uniformly distributed around the receiving end of the coupling assembly.

[0022] In one embodiment, the apparatus is an earthing apparatus or a grounding apparatus.

[0023] In one embodiment, the apparatus is a termination apparatus.

[0024] In one embodiment, the earth coupling means comprises a tapered portion. A circumference of the earth coupling means may taper.

[0025] In another aspect, a system for electrically terminating a cable is provided, the cable being suitable for transmission of power with voltage levels greater than or equal to 1 kV, the cable comprising a conductive core and an earthing screen layer, the conductive core and earthing screen layer being coaxially arranged relative to each other, the system comprising: a coupling assembly comprising a receiving end configured to receive a connecting end of the cable; an earth coupling means configured to be coaxially positioned to surround the receiving end of the cylindrical connection assembly; and an insulating sleeve configured to be coaxially positioned to surround the earth coupling means in a manner such that the earth coupling means is pressed against the receiving end of the coupling assembly, wherein the receiving end of the coupling assembly, the earth coupling means and the insulating sleeve each have a substantially cylindrical shape, and wherein, in use, the earthing screen layer at the connecting end of the cable is received between the earth coupling means and the receiving end of the coupling assembly such that when the insulating sleeve surrounds and presses the earth coupling means against the receiving end of the coupling assembly, an electrical termination of the cable onto the coupling assembly is generated.

[0026] In one embodiment, the coupling assembly comprising a core connecting means configured to connect to the conductive core at the connecting end of the cable.

[0027] In one embodiment, the coupling assembly comprises a body comprising the receiving end and a core connecting means positioned within the body, the core connecting means being configured to connect to the conductive core at the connecting end of the cable.

[0028] The insulating sleeve may comprise an internal threaded surface.

[0029] The earth coupling means may comprise a tapered portion. A circumference of the earth coupling means tapers.

[0030] Brief Description of the Drawings

[0031] Notwithstanding any other forms which may fall within the scope of the disclosure as set forth in the Summary, specific embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

[0032] Figure 1 is an exploded schematic representation of an apparatus in accordance with an embodiment;

[0033] Figure 2 is a three-dimensional schematic representation of a close-up perspective view of an apparatus in accordance with an embodiment;

[0034] Figure 3 is a photograph showing a perspective view of an apparatus and cable received by the apparatus in accordance with an embodiment;

[0035] Figure 4a is a schematic representation of an earthing screen layer of a cable arranged at a part of the apparatus in accordance with an embodiment; Figure 4b is a three-dimensional schematic representation of the cable and earth screening layer shown in Figure 4a with the earth coupling means of the apparatus arranged in accordance with an embodiment;

[0036] Figure 4c is a three-dimensional schematic representation of the cable and earth screening layer shown in Figures 4a and 4b with the apparatus arranged in accordance with an embodiment;

[0037] Figure 5 is a three-dimensional schematic representation of a three-phase cable, each phase being received by an apparatus provided in accordance with an embodiment; and

[0038] Figure 6 is a schematic representation of the apparatus in accordance with an embodiment.

[0039] Detailed Description

[0040] With references to Figures 1 to 3, there is shown an apparatus 10 provided in accordance with an embodiment. The apparatus 10 is for a cable 12 for transmission of power, the cable 12 comprising a conductive core (not shown) and an earthing screen layer 13. The apparatus 10 comprises a coupling assembly 14 comprising a receiving end 16 arranged to receive a connecting end (not shown) of the cable 12. The apparatus 10 further comprises an earth coupling means 20 arranged at the receiving end 16 of the coupling assembly 14. The apparatus 10 further comprises an insulating sleeve 22 arranged at the earth coupling means 20 such that the earth coupling means 20 contacts the receiving end 16 of the coupling assembly 14. When the cable 12 is received by the apparatus 10, the earthing screen layer 13 at the connecting end of the cable 12 is arranged to be intermediate the earth coupling means 20 and the receiving end 16 of the coupling assembly 14.

[0041] The cable 12 is suitable for transmission of power. The cable 12 may be suitable for transmission of power with voltage levels greater than or equal to 1 kV.

[0042] The cable 12 may be suitable for transmission of power at high frequencies.

[0043] In one embodiment, when the cable 12 is received by the apparatus 10, the earthing screen layer 13 is in secure contact with the earth coupling means 20 and the receiving end 16 of the coupling assembly 14. In one embodiment, the earth coupling means 20 is in secure contact with the receiving end 16 of the coupling assembly 14.

[0044] In one embodiment, the earth coupling means 20 is in forced contact against the receiving end 16 of the coupling assembly 14.

[0045] In one embodiment, the earthing screen layer 13 is in forced contact with the earth coupling means 20 and the receiving end 16 of the coupling assembly 14.

[0046] With reference to Figures 1 to 6, the securement or force of the contact between the earth coupling means 20, the receiving end 16 of the coupling assembly 14 and the earthing screen 13 is provided by a screw-type engagement of the insulating sleeve 22.

[0047] However, it will be understood that other the securement or force means are envisaged. For example, the securement or force of the contact between the earth coupling means 20, the receiving end 16 of the coupling assembly 14 and the earthing screen 13 may be provided by a snap-fit engagement of the insulating sleeve 22.

[0048] The apparatus 10 also comprises a phase insulator 17. The apparatus 10 can also comprise a retention clip 15.

[0049] In one embodiment, when the cable 12 is received by the apparatus 10, the earthing screen layer 13 of the cable 12 is positioned in between the earth coupling means 20 and a receiving end 16 of the coupling assembly 14. The earthing screen layer 13 of the cable 12 may be positioned in between the earth coupling means 20 and a receiving end 16 of the coupling assembly 14 such that the earthing screen layer 13 is secured in position between the earth coupling means 20 and the receiving end 16 of the coupling assembly 14. The earthing screen layer 13 of the cable 12 may be positioned in between the earth coupling means 20 and a receiving end 16 of the coupling assembly 14 such that the earthing screen layer 13 is in secure contact with the earth coupling means 20 and the receiving end 16 of the coupling assembly 14.

[0050] The apparatus 10 may be an earthing or grounding apparatus. The apparatus 10 may be a terminating apparatus.

[0051] The receiving end 16 of the coupling assembly 14 may comprise a terminated end 16a that is to be terminated to the cable 12. In one embodiment, the coupling assembly 14 comprises a body 24 comprising the receiving end 16 and a core connecting means 26 positioned within the body 24, the core connecting means 26 being configured to connect to the conductive core at the connecting end of the cable 12.

[0052] In one embodiment, the core connecting means 26 comprises a thimble or plug 28 and a pin 30. The thimble or plug 28 may be arranged to receive and connect to the conductive core at the connecting end of the cable 12.

[0053] In one embodiment, the apparatus 10 provides a coaxial termination 31, which provides the following advantages or benefits: the coaxial termination mitigates the issue of harmful currents being injected into the earthing system typically generated by high-frequency inverters. the coaxial termination is suitable for VSD (Variable Speed Drive) and VVVF (Variable Voltage and Variable Frequency) applications. the coaxial termination is suitable and advantageous for use in high power inverter fed systems.

[0054] The apparatus 10 in accordance with embodiments of the present disclosure, when a cable 12 is received by the apparatus 10, provides a contiguous earth path and maintains the integrity and function of the cable constructions at the termination 31 and earthing provided by the apparatus 10. The apparatus 10 in accordance with embodiments of the present disclosure allows only phase to earth faults through the insulating sleeve 22.

[0055] With reference to Figures 1 to 6, the receiving end 16 of the coupling assembly 14, the earth coupling means 20 and the insulating sleeve 22 are substantially cylindrical, i.e. have a substantially cylindrical shape. The earth coupling means 20 comprises a tapered portion 32. A circumference of the earth coupling means 20 tapers.

[0056] With particular reference to Figures 1 to 4, the tapered portion 32 comprises a plurality of elongated strips or fingers 33 arranged circumferentially. The elongated fingers 33 may be arranged equidistantly circumferentially. This structure of the tapered portion 32 provides flexibility for insertion of the cable 12 earthing screen layer 13. The elongated fingers 33 can splay out slightly as the cable 12 earthing screen layer 13 is pushed through and then compressed between the earth coupling means 20 and the coupling assembly 14 during the termination process. As best illustrated in Figure 3, to maintain cable integrity, weaved portions of the cable 12 earthing screen layer 13 are compressed between the earth coupling means 20 and the coupling assembly 14 when the termination is completed. The position and arrangement of the cable 12 earthing screen layer 13 in between the earth coupling means 20 and the coupling assembly 14 is such that the cable 12 earthing screen layer 13 weave, and consequently the integrity of the cable 12, can be maintained as much as possible. The cable 12 earthing screen layer 13 must be in contact with each strip or finger 33 of the earth coupling means 20 and along each strip length.

[0057] It will be understood that the tapered portion 32 may have different structures from the one illustrated in Figures 1 to 4, as may be found suitable by a skilled person. For example, the tapered portion 32 may be a solid tapering cylindrical portion.

[0058] In one embodiment, although not illustrated, the insulating sleeve 22 comprises an internal threaded surface. It will be understood that other internal surfaces are envisaged for the insulated sleeve 22. For example, the internal surface of the insulated sleeve 22 may be smooth, or in another example, may be corrugated.

[0059] With reference to Figures 1 to 6, the conductive core (not shown) and earthing screen layer 13 of cable 12 are coaxially arranged relative to each other. The earth coupling means 20 is configured to be coaxially positioned to surround the receiving end 16 of the coupling assembly 14. The insulating sleeve 22 is configured to be coaxially positioned to surround the earth coupling means 20 in a manner such that the earth coupling means 20 is pressed against the receiving end 16 of the coupling assembly 14. The receiving end 16 of the coupling assembly 14, the earth coupling means 20 and the insulating sleeve 22 each have a substantially cylindrical shape. In use, the earthing screen layer 13 at the connecting end of the cable 12 is received between the earth coupling means 20 and the receiving end 16 of the coupling assembly 14 such that, when the insulating sleeve 22 surrounds and presses the earth coupling means 20 against the receiving end 16 of the coupling assembly 14, an electrical termination of the cable 12 onto the coupling assembly 14 is generated.

[0060] The earth coupling means 20 may comprise a conductive material 34. The conductive material 34 may be a metallic material.

[0061] A circumferential connection provided by the apparatus 10 maintains integrity of cable construction when the cable 12 is terminated to the apparatus 10. The earth coupling means 20 secures the earthing screen layer 13 of the cable 12 onto the receiving end 16 of the coupling assembly 14. The insulating sleeve 22, when screwed (or in another example embodiment snap-fitted) to the earth coupling means 20, compresses the earth coupling means 20 against the cable 12 earthing screen layer 13. This, combined with the conductivity of the earth coupling means 20, makes for a secure termination of the cable 12 onto the coupling assembly 14 or receiving end 16 of the coupling assembly 14.

[0062] By using a circumferential termination 31 to the coupling assembly 14, the coupling assembly 14 doesn’t become part of the problem as it is an extension of the cable 12, functionally.

[0063] The circumferential termination 31 allows for a uniform distribution of the cable 12 earthing screen layer 13 around the power conductor while maintaining segregation from other earthing mediums within the coupler system, i.e. apparatus 10.

[0064] The connection / termination 31 provided by the apparatus 10 must, in accordance with an embodiment, be of an extremely low impedance uniformly distributed around the coupling assembly 14 to be appropriately suitable for use with an inverter fed system.

[0065] Embodiments of the present disclosure provide an apparatus 10 for transmission of power via cables 12 wherein the reference and functional earths are not bonded or joined together. When bonded or joined together, a current may be superimposed on the functional earth. Likewise, if the termination is not uniformly connected to the coupling assembly (i.e., not circumferential) there may be an imbalance caused by the impedance at the termination not being uniform resulting in a similar issue. This harmful current is a hazard to persons in the vicinity of connected equipment. The apparatus 10 for a cable 12 provided in accordance with embodiments of the present disclosure thus enable limiting the injection of currents into the earthing system. Such injection can for example be generated by high-frequency inverters.

[0066] The apparatus 10 in accordance with embodiments of the present disclosure is for example advantageous for use with cables 12 where the earthing screen layer 13 of the cable 12 is used as a reference earth segregated from the functional earth within the cable 12. This cable type is widely used in the field of high-power inverter fed machines where high frequency switching frequencies are used as part of the pulse width modulation (PWM). With reference to Figures 4 and 5, the cable 12 can be a three-phase cable 12a wherein each phase 12b, 12c, 12d of the cable 12a is terminated using the apparatus 10 as described above. It will be understood that although the apparatus 10 has been described with features having a substantially cylindrical shape and coaxially arranged, other shapes and / or geometrical arrangements as may be found suitable by a skilled person are considered to be within the scope of the present disclosure. In the claims which follow and in the preceding description of the disclosure, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features in various embodiments of the invention.

[0067] Modifications and variations as would be apparent to a skilled addressee are determined to be within the scope of the present disclosure.

Claims

Claims1. An apparatus for a cable for transmission of power, the cable comprising a conductive core and an earthing screen layer, the apparatus comprising: a coupling assembly comprising a receiving end arranged to receive a connecting end of the cable; an earth coupling means arranged at the receiving end of the coupling assembly; and an insulating sleeve arranged at the earth coupling means such that the earth coupling means contacts the receiving end of the coupling assembly, and wherein, when the cable is received by the apparatus, the earthing screen layer at the connecting end of the cable is arranged to be intermediate the earth coupling means and the receiving end of the coupling assembly.

2. The apparatus according to claim 1 , wherein, when the cable is received by the apparatus, the earthing screen layer is in secure contact with the earth coupling means and the receiving end of the coupling assembly.

3. The apparatus according to claim 1 or claim 2, wherein the earth coupling means is in secure contact with the receiving end of the coupling assembly.

4. The apparatus according to any one of the preceding claims, wherein the earth coupling means is in forced contact against the receiving end of the coupling assembly.

5. The apparatus according to any one of the preceding claims, wherein the earthing screen layer is in forced contact with the earth coupling means and the receiving end of the coupling assembly.

6. The apparatus according to any one of claims 2 to 5, wherein the securement or force is provided by a screw-type engagement of the insulating sleeve.

7. The apparatus according to any one of claims 2 to 6, wherein the securement or force is provided by a snap-fit engagement of the insulating sleeve.

8. The apparatus according to any one of the preceding claims, wherein the arrangement of the earthing screen layer at the connecting end of the cable intermediate the earth coupling means and the receiving end of the coupling assembly electrically terminates the cable onto the coupling assembly.

9. The apparatus according to any one of the preceding claims, wherein the insulating sleeve substantially circumferentially contacts the earth coupling means against the receiving end of the coupling assembly.

10. The apparatus according to any one of the preceding claims, wherein there are multiple points of contact between the insulating sleeve and earth coupling means, the multiple points of contact being circumferentially arranged.

11. The apparatus according to any one of the preceding claims, wherein the earth coupling means comprises a conductive material.

12. The apparatus according to claim 11, wherein the conductive material comprises a metallic material.

13. The apparatus according to any one of the preceding claims, wherein the conductive core and earthing screen layer are coaxial.

14. The apparatus according to any one of the preceding claims, wherein the earth coupling means and the receiving end of the cylindrical connection assembly are coaxial.

15. The apparatus according to any one of the preceding claims, wherein the receiving end of the coupling assembly, the earth coupling means and the insulating sleeve are substantially cylindrical.

16. The apparatus according to any one of the preceding claims, wherein the cable is suitable for transmission of power with voltage levels greater than or equal to 1 kV.

17. The apparatus according to any one of the preceding claims, wherein the apparatus is characterised by a low impedance.

18. The apparatus according to any one of the preceding claims, wherein the apparatus is characterised by a substantially low impedance uniformly distributed around the receiving end of the coupling assembly.

19. The apparatus according to any one of the preceding claims, wherein the apparatus is an earthing apparatus, a grounding apparatus or a termination apparatus.

20. The apparatus according to any one of the preceding claims, wherein the earth coupling means comprises a tapered portion.

21. The apparatus according to claim 20, wherein a circumference of the earth coupling means tapers.

22. A system for electrically terminating a cable suitable for transmission of power with voltage levels greater than or equal to 1 kV, the cable comprising a conductive core and an earthing screen layer, the conductive core and earthing screen layer being coaxially arranged relative to each other, the system comprising: a coupling assembly comprising a receiving end configured to receive a connecting end of the cable; an earth coupling means configured to be coaxially positioned to surround the receiving end of the cylindrical connection assembly; and an insulating sleeve configured to be coaxially positioned to surround the earth coupling means in a manner such that the earth coupling means is pressed against the receiving end of the coupling assembly, wherein the receiving end of the coupling assembly, the earth coupling means and the insulating sleeve each have a substantially cylindrical shape, and wherein, in use, the earthing screen layer at the connecting end of the cable is received between the earth coupling means and the receiving end of the coupling assembly such that when the insulating sleeve surrounds and presses the earth coupling means against the receiving end of the coupling assembly, an electrical termination of the cable onto the coupling assembly is generated.

23. The system according to claim 22, wherein the coupling assembly comprises a body comprising the receiving end and a core connecting means positioned within the body, the core connecting means being configured to connect to the conductive core at the connecting end of the cable.

24. The system according to claim 22 or 23, wherein the insulating sleeve comprises an internal threaded surface.

25. The system according to any one of claims 22 to 24, wherein the earth coupling means comprises a tapered portion.

26. The system according to claim 25, wherein a circumference of the earth coupling means tapers.

Images