WO2020160570A2

WO2020160570A2 - A method of rendering a cable and/or an owner of a cable identifiable

Info

Publication number: WO2020160570A2
Application number: PCT/ZA2019/050004
Authority: WO
Inventors: Cecil Albert Mitchell
Original assignee: Cecil Albert Mitchell
Priority date: 2016-06-01
Filing date: 2019-02-05
Publication date: 2020-08-06
Also published as: ZA201603726B

Abstract

A method of rendering an electrical power cable (13) identifiable by impregnating a plurality of discrete identifiers (12), in the form of very small hexagonal discs, into interstices of the electrical cable (13) through use of a carrier medium in the form of a cable rejuvenation fluid (11) which is configured to expel moisture from voids in the dielectric layer of the cable in order to reverse the adverse effects of electrochemical degradation of ageing cables. Each identifier (12) is configured to render the cable identifiable by including proprietary identification data associated with the owner of the cable which is unreadable to the naked human eye. In this example embodiment of the invention, the identifiers (12) comprise metallic microdots. The fluid (11) prolongs the service life of the cable whilst the microdots significantly increase the chances of positive identification of stolen cables which could lead to arrest of suspects thereby discouraging theft.

Description

A method of rendering a cable and/or an owner of a cable identifiable

FIELD OF INVENTION

The invention relates generally to electrical cable security, and specifically to a method of rendering a cable and/or an owner of a cable identifiable to ensure that a rightful owner of a cable can be traced in order to discourage cable theft.

BACKGROUND OF INVENTION

Cable theft has become an ever increasing problem and is rife in South Africa as well as in other countries across the world. Thieves are after the metallic cores of cables because of the high resale or scrap metal value of scarce metals such as copper. Cable theft causes great disruption, inconvenience and sometimes temporary loss of power, not to mention financial loss due to the replacement costs of stolen cables.

It has proven problematic to establish true proprietorship or ownership of cables in the event that a thief is caught with stolen cables. For this reason, outer sheaths of the cables have been marked in various ways to render the cables identifiable which could assist in putting thieves to justice when caught. These existing methods of marking or identifying a cable are proving to be unreliable as the thieves simply remove the identification marks by, for example, burning or otherwise destroying the outer sheaths. The present invention aims, at least to some extent, to alleviate the drawbacks discussed above.

SUMMARY OF INVENTION

In accordance with the invention, there is provided a method of rendering a cable and/or an owner of a cable identifiable, the method including the steps of:

impregnating a plurality of discrete identifiers into interstices of the cable, the identifiers being carried in a carrier medium which is impregnated into the interstices, wherein at least one of the identifiers is configured to render the cable identifiable by including proprietary identification data which is unreadable to the naked human eye.

The method may include injecting the carrier medium containing the identifiers into the interstices. This may include creating a pressure differential across a length of the cable in order to force the carrier medium into the interstices. The pressure differential may be created by applying a pressurised supply of the carrier medium to one end of the length of cable. Alternatively, or in addition, the pressure differential may be created by creating a vacuum at one end of the length of cable using a suction device. The identifiers may be entrained in the carrier medium, the carrier medium being a fluid. The carrier medium may be a gas. The carrier medium may be a liquid solution. Furthermore, the carrier medium may be in the form of an electrical cable rejuvenation fluid. The fluid may be an anti-treeing additive.

The fluid may be a silane anti-treeing additive which is configured to improve dielectric properties of the cable when applied thereto thereby reversing the adverse affects of electrochemical tree formation in a dielectrical layer of the cable and prolonging the life of the cable. The identifiers may comprise metallic microdots. The microdots may have a diameter in the range of 0.05 mm to 3.0 mm. The proprietary identification data may comprise indicia. The indicia may be machine-readable. The indicia may be identifiable when subjected to optical magnification. The cable may be an electrical power cable.

The invention extends to a cable which includes a plurality of discrete identifiers, at least one of which is configured to render the cable and/or an owner of a cable identifiable by including proprietary identification data which is unreadable to the naked human eye, the discrete identifiers being disposed throughout interstices of the cable.

The identifiers may be entrained in a carrier medium which is injected into the interstices. The carrier medium may be an electrical cable rejuvenation fluid. The cable may be created by following any one of the method steps described above.

The invention also extends to an electrical cable rejuvenation fluid which includes a multiplicity of discrete identifiers entrained therein, wherein each identifier is configured to render an electrical cable and/or an owner of an electrical cable identifiable by including proprietary identification data which is unreadable to the naked human eye. The identifiers may be microdots.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying figure showing an apparatus used to carry out the method in accordance with the invention.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiments described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

Although the invention described herein refers specifically to electrical power cables, it is to be appreciated that the invention is not intended to be limited in this manner to electrical power cables. In other words, the invention may be useful for other types of cables including electrical communication cables, wires or the like.

A first aspect of the invention relates to the use of a plurality of discrete identifiers in a method of rendering a cable and/or an owner of a cable identifiable wherein the discrete identifiers are impregnated into interstices of the electrical cable using a carrier medium which may be in the form of a gas, liquid or gel solution. Each identifier is configured to render the cable identifiable by including proprietary identification data which is unreadable to the naked human eye. In this example embodiment of the invention, the identifiers comprise microdots. Microdots or Datadots are very tiny, in some instances microscopic, hexagonal discs or platelets that include proprietary identification data such as indicia (letters and/or numerals and/or symbols), colours, holographic surfaces or the like which are associated with a particular proprietor. Microdots are known in the art and are applied to some objects to act as identifiers or identification tags which render the object or an owner of the object to which the microdot has been applied identifiable. Although metallic (i.e. nickel, gold, metallised polymer, silver) or ceramic microdots are preferred for heat and fire resistance reasons, polymeric microdots may also be used.

Metallic microdots typically have diameters ranging from 0.05mm to 3.0mm and are between 1 pm to 15pm thick. Microdots are difficult to remove from an object and can withstand temperatures of up to 1000°C. Due to the size of the microdots, identification data recorded thereon is generally not readable with the naked human eye. However, optical magnification instruments such as magnifying glasses or a microscope can be used to read the data from the microdots. Alternatively, in the event that the identification data is in the form of barcodes, the microdots may be machine-readable using a laser beam. Other electronically readable configurations such as RFID based configurations are also conceivable.

A second aspect addressed by the invention relates to the prolonging of the service life of electrical power cables. One of the problems inherent in underground cable systems is the ingress of moisture into the cable insulating layer, leading to decomposition of the dielectric insulation layer and failure of the cable. It is well known that the intermolecular spaces of polyolefin sheaths or insulation layers are relatively large which allows moisture molecules to become infused in the layer. This renders these types of insulation layers susceptible to a type of insulation deterioration known as electrochemical tree formation. The term “tree” has been used since the area of failure in the insulation layer is a void space having the appearance of tree foliage. Treeing develops slowly and takes many years to cause failure of the cable. The occurrence of this phenomenon is well documented and will therefore not be discussed further here. Many cable installations, particularly cable installations in South Africa, have reached an age where electrochemical tree formation has become a problem.

A known solution to this problem is to introduce a cable rejuvenation fluid having a low moisture content into interstices of the cable in order to flush moisture from the cable. Cable rejuvenation technology involves the treatment of cross-linked polyethylene (XLPE) and EPR cables over 25 years old. Through the 1980’s, underground XLPE cables were manufactured using a steam-curing process which introduced water and ionic impurities into the insulation resulting in electrochemical degradation of its dielectric properties over the cable’s service life. The rejuvenation process involves injecting a silicon-based fluid under pressure into the spaces between conductor strands. This fluid may comprise nitrogen, silicon or a silane additive such as organosilanes or other polymeric compositions containing silane oligomers. The unique properties of the injection fluid cause oligomerization with water molecules in the tree. Resultant larger molecules fill the void, repairing the dielectric properties. These fluids are sometimes referred to as anti-treeing agents or dielectric fluids. Various cable rejuvenation fluid compositions have been developed over the years to address this specific problem. The resultant effect is restored cable dielectrics and extended cable life of 30-40 years.

In the Figure a rejuvenation apparatus is designation by numeral 10. The apparatus 10 is attached to a length of cable 13 which is to be rendered identifiable through the introduction of microdots 12 as well as to be treated with rejuvenation fluid 11. Accordingly, the invention aims to address two drawbacks associated with electrical power cables, the first relating to an inability to positively identify an owner of a cable in the event that the cable is stolen or tampered with and, the other relating to the decomposition of dielectric layers of the cables.

Accordingly, a multiplicity of discrete identifiers in the form of microdots 12 containing unique proprietary identification data associated with one or more owners of a length of cable 13 is mixed with a silane anti-treeing or cable rejuvenation fluid 11 which also acts as a carrier medium for the microdots 12. The fluid 11 is introduced into a container 14 which is pressurised using compressed air and is connected by way of suitable piping 15 and an end cap 16 having an inlet/outlet valve configuration to a first end of the length of cable 13. The end cap 16 sealingly abuts the first end of the length of cable 13 in order to allow the microdots 12 to be injected into interstices in the cable 13 until the entire length of cable 13 is impregnated with the microdots 12 entrained in the rejuvenation fluid 11. To further this process, a further end cap 17 having a similar inlet/outlet valve arrangement is connected to an opposite end of the length of cable 13. This end cap 17 is connected to a suction device which creates a vacuum and sucks the fluid 11 into the interstices in the cable 13.

No criminal wants to be caught in possession of identifiable stolen goods which place them at risk of conviction. The microdots are so small it is almost impossible to remove all of them from an item. In addition, cables will be marked as being infused with microdots which will act as a deterrent to thieves. The microdots are made of nickel and are virtually impossible to destroy. Even if the copper core of a cable is granulated the microdots will still be present and retrievable. Typically, the cost to rejuvenate cables is a fraction of cable replacement. Many times, the cost savings can be even greater if the area is highly landscaped, difficult to access, or the soil is rocky. With cable rejuvenation, the circuit owner can stretch their capital budget two or more times and have a more significant impact on system reliability. Cable rejuvenation is also faster than cable replacement. Typically, it takes one-third the time to rejuvenate a cable compared to replacement. This increased productivity allows the circuit owner to spend yearend money faster, when the situation demands. Also, when replacing cables, the impact on electricity customers must be borne in mind. Cable rejuvenation is more customer friendly than cable replacement. Furthermore, there is no equipment noise. The injection equipment is small, the process is fast, and there is almost no disruption to established landscaping. Typically, 3-5 segments can be completed per day almost silently with no customer inconvenience. The method can be applied to new cable installations. This allows any cable, no matter how small the segment, to be positively identified by law enforcement officials by reading the microdot data and obtaining accurate information from an existing database using a mobile phone or other suitable device. The Inventor believes that the method in accordance with the invention provides an effective way of permanently marking cables thereby rendering the cables identifiable which will discourage cable theft as well as extending service life of the cables by way of the rejuvenation fluid. The microdots can also be sprayed onto electrical switchgear and other substation components.

Claims

A method of rendering a cable and/or an owner of a cable identifiable

1. A method of rendering a cable and/or an owner of a cable identifiable, the method including the steps of:

2. A method as claimed in claim 1 , which includes injecting the carrier medium containing the identifiers into the interstices.

3. A method as claimed in claim 1 or 2, which includes creating a pressure differential across a length of the cable in order to force the carrier medium into the interstices.

4. A method as claimed in claim 3, wherein the pressure differential is created by applying a pressurised supply of the carrier medium to one end of the length of cable.

5. A method as claimed in claim 3 or 4, wherein the pressure differential is created by creating a vacuum at one end of the length of cable using a suction device.

6. A method as claimed in any one of the preceding claims, wherein the identifiers are entrained in the carrier medium, the carrier medium being a fluid.

7. A method as claimed in claim 6, wherein the carrier medium is a gas.

8. A method as claimed in claim 6, wherein the carrier medium is a liquid solution.

9. A method as claimed in claim 8, wherein the carrier medium is in the form of an electrical cable rejuvenation fluid.

10. A method as claimed in claim 9, wherein the fluid is an anti-treeing additive.

11. A method as claimed in claim 10, wherein the fluid is a silane anti treeing additive which is configured to improve dielectric properties of the cable when applied thereto thereby reversing the adverse affects of electrochemical tree formation in a dielectrical layer of the cable and prolonging the life of the cable.

12. A method as claimed in any one of the preceding claims, wherein the identifiers comprise metallic microdots.

13. A method as claimed in claim 12, wherein the microdots have a diameter in the range of 0.05 mm to 3.0 mm.

14. A method as claimed in claim 12 or 13, wherein the proprietary identification data comprises indicia.

15. A method as claimed in claim 14, wherein the indicia is machine- readable.

16. A method as claimed in claim 14 or 15, wherein the indicia is identifiable when subjected to optical magnification.

17. A method as claimed in any one of the preceding claims, wherein the cable is an electrical power cable.

18. A cable which includes a plurality of discrete identifiers, at least one of which is configured to render the cable and/or an owner of a cable identifiable by including proprietary identification data which is unreadable to the naked human eye, the discrete identifiers being disposed throughout interstices of the cable.

19. A cable as claimed in claim 18, wherein the identifiers are entrained in a carrier medium which is injected into the interstices.

20. A cable as claimed in claim 19, wherein the carrier medium is an electrical cable rejuvenation fluid.

21. A cable as claimed in any one of claims 18 to 20, which is created by following any one of the method steps of claims 1 to 17.

22. An electrical cable rejuvenation fluid which includes a multiplicity of discrete identifiers entrained therein, wherein each identifier is configured to render an electrical cable and/or an owner of an electrical cable identifiable by including proprietary identification data which is unreadable to the naked human eye.

23. A rejuvenation fluid as claimed in claim 22, wherein the identifiers are microdots.