US3789130A - Tamper proof electrical cables - Google Patents

Tamper proof electrical cables Download PDF

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Publication number
US3789130A
US3789130A US00163060A US3789130DA US3789130A US 3789130 A US3789130 A US 3789130A US 00163060 A US00163060 A US 00163060A US 3789130D A US3789130D A US 3789130DA US 3789130 A US3789130 A US 3789130A
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United States
Prior art keywords
cable
mineral insulated
power cable
electric
conductor
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Expired - Lifetime
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US00163060A
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English (en)
Inventor
H Parker
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Pyrotenax Ltd
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Pyrotenax Ltd
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/32—Insulated conductors or cables characterised by their form with arrangements for indicating defects, e.g. breaks or leaks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/16—Rigid-tube cables

Definitions

  • An electric power or communication cable incorporates a mineral insulated cable of a cross-section that is small in comparison with the overall cross-section of the cable, a conductor or conductors of the mineral insulated cable being adapted to carry a signal other than the normal power or signalling load of the power or communication cable.
  • the or each mineral insulated cable is so located in the cable that it is not easily recognized as an alarm circuit by a thief.
  • an electric power cable having annourmg or a concentric screen or neutral conductor comprising wires applied as a continuous helical lapping or with periodically reversing lay one or more of the wires may be replaced by a mineral insulated cable.
  • This invention relates to electric power and communication cables incorporating an auxiliary signalling circuit adapted to operate an alarm when the cable is cut or severely damaged.
  • the principal object of the invention is to provide a cable incorporating one or more conductors which are suitable for connection in an alarm circuit and which are not easily accessible to a thief who wishes to put the alarm circuit out of action to enable him to steal a length of the cable.
  • an electric power or communicationcable incorporates a mineral insulated cable of a cross-section that is small in comparison with the overall cross-section of the cable, a conductor or conductors of the mineral insulated cable being adapted to carry a signal other than the normal power or signalling load of the power or communication cable.
  • the term mineral insulated cable means a cable comprising a metal sheath enclosing one or more conductors which is or are separated from the sheath (and from each other when there is more than one conductor) by a compacted inorganic powder, usually magnesium oxide.
  • the mineral insulated cable can be incorporated in any part of the cable in a position where it does not interfere with the normal functioning of the cable, for example it may be embedded in a plastics sheath of the cable, it is preferably incorporated in such a way that it is not easily recognised as an alarm circuit by a thief.
  • the mineral insulated cable may for example replace one or more of the armouring wires or one or more of the wires of a concentric screen or neutral conductor, whether applied as a continuous helical lapping or with periodically reversing lay.
  • the sheath of the mineral insulated cable is preferably of the same external diameter as the wire or wires that it replaces and is preferably made of a material or coated with a material that is the same as or resembles that of the surface of the wire or wires that it replaces.
  • the mechanical strength (both tensile and compression) of the mineral insulated cable is preferably such that it can be incorporated in the cable by means of the normal machinery used in manufacturing the cable. It will usually not be necessary to make it of especially low tensile strength such that it is easily broken by a thief, since heavy cables of the kind containing sufficient metal to attract a thief will normally have be sawn through by the thief.
  • the principal object of the invention is to protect an electric cable against theft, it will be appreciated that the alarm circuit to which the mineral insulated cable is connected will operate whenever the electric cable is severely damaged, either accidentally or intentionally. For this reason it may in some circumstances be advantageous to incorporate in the electric cable more than one mineral insulated cable and to distribute these cables at spaced intervals around the periphery of the electric cable, for example four mineral insulated cables can be used to replace four armour wires spaced at intervals of 90.
  • the invention includes a cable installation incorporating any form of cable described above with at least one conductor of the or each mineral insulated cable connected in an alarm circuit.
  • FIGS. 1 and 2 illustrate cross-sectional views of typical forms of mineral insulated cable that can be incorporated in electric power or communication cables
  • FIG. 3 is a cross-sectional view of an electric service cable in accordance with the invention generally used for connecting a consumer, eg a house or factory, to an electric power distribution cable,
  • FIG. 4 is a sectional side view of a cut-back end of a three-core electric power distribution cable in accordance with the invention.
  • FIG. 5 is a cross-sectional view of a four-core electric power cable in accordance with the invention.
  • the mineral insulated cable shown in FIG. I is a conventional single core cable comprising a single conductor 1 separated from a metal sheath 3 by compacted magnesium oxide 2.
  • two conductors l are separated from each other and from the metal sheath 3 by compacted magnesium oxide 2.
  • the consumer service cable illustrated in FIG. 3 comprises a single solid aluminium conductor 11, a layer of plastics material 12 constituting the conductor dielectric, a concentric layer 14 of round metal wires lapped helically about the conductor dielectric to form the neutral conductor and, enclosing the assembly, a sheath 13 of plastics material.
  • Embedded in the sheath 13 and spaced at intervals of around the periphery of the cable are four mineral insulated cables 15 of the type shown in FIG. 1 whose conductors I can be connected in an appropriate alarm circuit when the service cable is installed.
  • the mineral insulated cables 15 may each extend substantially parallel to the axis of the cable or each may follow a helical path about the cable.
  • the distribution cable shown in FIG. 4 is a three-core paper-insulated lead sheathed single-wire armoured llkV cable comprising three stranded conductors 21 each of which has insulation 22 of lapped impregnated paper and a dielectric screen 26.
  • the three insulated conductors are surrounded by several layers of wire woven fabric tape 27 and are enclosed in a lead sheath 23.
  • a single layer of steel armouring wires 24 is lapped helically on conventional armour bedding 28 on the outside of the lead sheath 23 and the cable armouring is protected by conventional hessian serving 30.
  • At each of four positions spaced at intervals of 90 around the cable a mineral insulated cable 25 of the type shown in FIG.
  • each mineral insulated cable 25 has an external diameter equal to that of each of the armouring wires and is made of a material such as cupronickel or mild steel that causes the sheath to resemble the surfaces of the other armouring wires thereby ensuring that the mineral insulated cable is not easily recognised by a thief as the cable of an alarm circuit.
  • the further form of multi-core power cable shown in FIG. 5 is a four core cable suitable for use in a 1.1 kV
  • the cable is of conven tional construction except that one stranded conductor of the cable is replaced by a mineral insulated cable having four conductors.
  • the cable comprises three stranded conductors 31 and a mineral insulated cable 35 each enclosed in a separate body 32 of impregnated paper insulation, the cores so formed being laid up together with fillers 37 and surrounded by a belt 38 of impregnated paper.
  • a lead sheath 33 enclosed the laid-up cores and carries on its outer surface bedding 39 on which steel tape armour 34 is applied.
  • Serving 40 of conventional form is applied to the outer surface of the armour.
  • the metal sheath 43 of the mineral insulated cable 35 is adapted to serve as the neutral or earth continuity conductor of the cable and one or more of the four conductors 41 of the mineral insulated cable can be connected to a suitable alarm circuit.
  • the invention is primarily concerned with the provision of a cable incorporating one or more mineral insulated cables whose conductor or conductors are suitable for connection in an alarm circuit and are not easily accessible to a thief who wishes to put the alarm circuit out of action, in the case where a mineral insulated cable has a plurality of conductors, e.g. four, some or all of these conductors could be employed in a telecommunication circuit or for transmission of other types of electric signal.
  • An advantage of the cable of the present invention isthat, even if the mineral insulated cable is recognised by a thief, it is not easy for him to gain access to its conductor or conductors in such a way as to be able to connect them separately to a source of potential, such as a battery, so as to prevent operation of the alarm.
  • An electric cable comprising at least one core for carrying the normal load of the electric cable and, as an element of the cable, a mineral insulated cable having at least one conductor and a metal sheath, which mineral insulated cable is of a cross-section that is small in comparison with the overall cross-section of the electric cable and has at least one conductor adapted to carry a signal other than the normal load of the electric cable.
  • An electric cable comprising at least one core for carrying the normal load of the electric cable and, as an element of the cable, a mineral insulated cable having at least one conductor and a metal sheath, which mineral insulated cable is of cross-section that is small in comparison with the overall cross-section of the electric cable and has at least one conductor adapted to carry a signal other than the normal load of the electric cable, the mineral insulated cable being so located in the electric cable that it is not easily recognized as an alarm circuit by a thief.
  • An electric power cable comprising at least one core and, helically applied about the core, a layer of wires, wherein a mineral insulated cable having at least one conductor and a metal sheath constitutes an element of the layer of wires, the mineral insulated cable being ofa cross-section that is small in comparison with the overall crosssection of the power cable and at least one conductor adapted to carry a signal other than the normal load of the power cable.
  • a multi-core electric power cable having at least two cores for carrying the normal load of the power cable and as one core of the power cable a mineral insulated cable which has a metal sheath and at least one conductor adapted to carry a signal other than the normal load of the power cable, the core constituted by the mineral insulated cable being of substantially the same overall diameter as each of the cores carrying the normal load of the power cable.
  • the inventor's address reads --Zebbug; Malta, England-- It should read --Zebbug, Malta--.
  • the inventor's address reads --Zebbug; Malta, England-- It should read Zebbug, Malta--.

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  • Insulated Conductors (AREA)
US00163060A 1968-10-18 1969-10-10 Tamper proof electrical cables Expired - Lifetime US3789130A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB49575/68A GB1215388A (en) 1968-10-18 1968-10-18 Improvements in electric cables

Publications (1)

Publication Number Publication Date
US3789130A true US3789130A (en) 1974-01-29

Family

ID=10452798

Family Applications (1)

Application Number Title Priority Date Filing Date
US00163060A Expired - Lifetime US3789130A (en) 1968-10-18 1969-10-10 Tamper proof electrical cables

Country Status (6)

Country Link
US (1) US3789130A (xx)
CA (1) CA941918A (xx)
DE (1) DE1952157A1 (xx)
FR (1) FR2021015A1 (xx)
GB (1) GB1215388A (xx)
SE (1) SE370808B (xx)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4085653A (en) * 1976-09-15 1978-04-25 General Electric Company Ignition device
US4158185A (en) * 1976-04-06 1979-06-12 Aeg-Telefunken Kabelwerke Aktiengesellschaft, Rheydt Overhead transmission line with communication core
US4665281A (en) * 1985-03-11 1987-05-12 Kamis Anthony G Flexible tubing cable system
US4910360A (en) * 1989-01-05 1990-03-20 Noel Lee Cable assembly having an internal dielectric core surrounded by a conductor
US4937401A (en) * 1989-01-05 1990-06-26 Noel Lee Signal cable assembly including bundles of wire strands of different gauges
US5206642A (en) * 1990-05-11 1993-04-27 U.S. Philips Corporation Device for detecting data relating to the passage of vehicles on a road
US5558794A (en) * 1991-08-02 1996-09-24 Jansens; Peter J. Coaxial heating cable with ground shield
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple
US20080132118A1 (en) * 2006-11-30 2008-06-05 Honeywell International Inc. Secure connector with integrated tamper sensors
US20080134349A1 (en) * 2006-11-30 2008-06-05 Honeywell International Inc. Card slot anti-tamper protection system
US20090103224A1 (en) * 2007-10-19 2009-04-23 The Southern Company Fallen conductor warning system
US20090309577A1 (en) * 2008-06-06 2009-12-17 Weston Aerospace Limited High temperature speed sensor
US20110187531A1 (en) * 2009-12-14 2011-08-04 Apple Inc. Systems and methods for securing handheld electronic devices
EP2579278A1 (en) 2011-10-07 2013-04-10 Nexans Anti-theft cable
WO2014180664A1 (fr) * 2013-05-07 2014-11-13 Commissariat A L'energie Atomique Et Aux Energies Alternatives Surcouche destinee a recouvrir un objet, notamment un cable, pour la detection et/ou la localisation d'un defaut a sa surface
ES2522905A1 (es) * 2013-05-16 2014-11-19 Pedro Benito BERRIOBEÑA CELORRIO Método y sistema de detección del robo de un cable eléctrico
EP2937872A1 (de) * 2014-04-22 2015-10-28 Nexans Kabel für Gleisanlagen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2074777A (en) * 1934-03-14 1937-03-23 Coupier Marcel Marie Jo Eugene Concentric cable with mineral insulation
US2243851A (en) * 1940-06-06 1941-06-03 Bell Telephone Labor Inc Wire line transmission
US2341235A (en) * 1941-06-23 1944-02-08 Gen Cable Corp Insulated electrical conductor and method of manufacture
US2912600A (en) * 1958-05-19 1959-11-10 Hans D Isenberg Tamper protective system and cable for use therein
US3160871A (en) * 1962-04-02 1964-12-08 Gen Cable Corp Tap-proof security communications cable
US3697671A (en) * 1970-02-27 1972-10-10 Pyrotenax Ltd Electric cables

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2074777A (en) * 1934-03-14 1937-03-23 Coupier Marcel Marie Jo Eugene Concentric cable with mineral insulation
US2243851A (en) * 1940-06-06 1941-06-03 Bell Telephone Labor Inc Wire line transmission
US2341235A (en) * 1941-06-23 1944-02-08 Gen Cable Corp Insulated electrical conductor and method of manufacture
US2912600A (en) * 1958-05-19 1959-11-10 Hans D Isenberg Tamper protective system and cable for use therein
US3160871A (en) * 1962-04-02 1964-12-08 Gen Cable Corp Tap-proof security communications cable
US3697671A (en) * 1970-02-27 1972-10-10 Pyrotenax Ltd Electric cables

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Dummer Wires & R. F. Cables, Pitman London 1968, pp. 214 215. *

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4158185A (en) * 1976-04-06 1979-06-12 Aeg-Telefunken Kabelwerke Aktiengesellschaft, Rheydt Overhead transmission line with communication core
US4085653A (en) * 1976-09-15 1978-04-25 General Electric Company Ignition device
US4665281A (en) * 1985-03-11 1987-05-12 Kamis Anthony G Flexible tubing cable system
US4910360A (en) * 1989-01-05 1990-03-20 Noel Lee Cable assembly having an internal dielectric core surrounded by a conductor
US4937401A (en) * 1989-01-05 1990-06-26 Noel Lee Signal cable assembly including bundles of wire strands of different gauges
US5206642A (en) * 1990-05-11 1993-04-27 U.S. Philips Corporation Device for detecting data relating to the passage of vehicles on a road
US5558794A (en) * 1991-08-02 1996-09-24 Jansens; Peter J. Coaxial heating cable with ground shield
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple
US7796036B2 (en) * 2006-11-30 2010-09-14 Honeywell International Inc. Secure connector with integrated tamper sensors
US8279075B2 (en) 2006-11-30 2012-10-02 Honeywell International Inc. Card slot anti-tamper protection system
US20080132118A1 (en) * 2006-11-30 2008-06-05 Honeywell International Inc. Secure connector with integrated tamper sensors
US20080134349A1 (en) * 2006-11-30 2008-06-05 Honeywell International Inc. Card slot anti-tamper protection system
US20090103224A1 (en) * 2007-10-19 2009-04-23 The Southern Company Fallen conductor warning system
US7973672B2 (en) 2007-10-19 2011-07-05 The Southern Company Fallen conductor warning system having a disruption assembly
US8054195B2 (en) 2007-10-19 2011-11-08 The Southern Company Fallen conductor warning system
US20090309577A1 (en) * 2008-06-06 2009-12-17 Weston Aerospace Limited High temperature speed sensor
US20140340226A1 (en) * 2009-12-14 2014-11-20 Apple Inc. Systems and Methods For Securing Handheld Electronic Devices
US20110187531A1 (en) * 2009-12-14 2011-08-04 Apple Inc. Systems and methods for securing handheld electronic devices
US9373236B2 (en) * 2009-12-14 2016-06-21 Apple Inc. Systems and methods for securing handheld electronic devices
EP2579278A1 (en) 2011-10-07 2013-04-10 Nexans Anti-theft cable
WO2014180664A1 (fr) * 2013-05-07 2014-11-13 Commissariat A L'energie Atomique Et Aux Energies Alternatives Surcouche destinee a recouvrir un objet, notamment un cable, pour la detection et/ou la localisation d'un defaut a sa surface
FR3005524A1 (fr) * 2013-05-07 2014-11-14 Commissariat Energie Atomique Surcouche destinee a recouvrir un objet, notamment un cable, pour la detection et/ou la localisation d'un defaut a sa surface
US20160109394A1 (en) * 2013-05-07 2016-04-21 Commissariat A L'energie Atomique Et Aux Energies Alternatives Overlayer intended to cover an object, in particular a cable, in order to detect and/or locate a defect on the surface of same
ES2522905A1 (es) * 2013-05-16 2014-11-19 Pedro Benito BERRIOBEÑA CELORRIO Método y sistema de detección del robo de un cable eléctrico
EP2937872A1 (de) * 2014-04-22 2015-10-28 Nexans Kabel für Gleisanlagen

Also Published As

Publication number Publication date
DE1952157A1 (de) 1970-04-30
SE370808B (xx) 1974-10-28
FR2021015A1 (xx) 1970-07-17
GB1215388A (en) 1970-12-09
CA941918A (en) 1974-02-12

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