EP0858244A2 - Field free heating cable - Google Patents

Field free heating cable Download PDF

Info

Publication number
EP0858244A2
EP0858244A2 EP97120263A EP97120263A EP0858244A2 EP 0858244 A2 EP0858244 A2 EP 0858244A2 EP 97120263 A EP97120263 A EP 97120263A EP 97120263 A EP97120263 A EP 97120263A EP 0858244 A2 EP0858244 A2 EP 0858244A2
Authority
EP
European Patent Office
Prior art keywords
sheath
cable
conductors
conductor
resistance conductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97120263A
Other languages
German (de)
French (fr)
Other versions
EP0858244B1 (en
EP0858244A3 (en
Inventor
Tom Harald Birkeland
Kare Asper
Kristin Fagerhaug Sommerfelt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nexans SA
Original Assignee
Alcatel SA
Alcatel Alsthom Compagnie Generale dElectricite
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcatel SA, Alcatel Alsthom Compagnie Generale dElectricite filed Critical Alcatel SA
Publication of EP0858244A2 publication Critical patent/EP0858244A2/en
Publication of EP0858244A3 publication Critical patent/EP0858244A3/en
Application granted granted Critical
Publication of EP0858244B1 publication Critical patent/EP0858244B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/54—Heating elements having the shape of rods or tubes flexible
    • H05B3/56—Heating cables

Definitions

  • the present invention relates to electrical floor heating cables and in particular to cables generating acceptably small electromagnetic fields.
  • the magnetic field is best reduced/eliminated by a concentric shield, as in coaxial cables, but this is not a practical solution with heating cables.
  • the field generation problem can also be somewhat reduced by using two-conductor cables instead of single-conductor cables because the fields generated from the two conductors tend to eliminate each other.
  • the fields from two-conductor cables having a resistance conductor and a return conductor should - however - be further reduced.
  • the object of the present invention is to reduce the field generating properties of electrical floor heating cable having a first, near end and a second, far end and comprising within an outer protective sheath a cable core consisting of
  • a resistance conductor 1 is provided with a concentrical sheath 2 of insulation material such as crosslinked polyethylene. All embodiments have an outer protective sheath 4 of PVC or other suitable material and an earth screen 7 in contact with earth means 6 or 20.
  • the earth screen could be a conventional Al/PE tape in contact with Cu wires 6 or 20.
  • the resistance conductor can be substituted with a cold end copper conductor.
  • Return conductors 5;10,11;15,16,17 are embedded in a common insulation sheath 3 arranged over the resistance conductor sheath 2.
  • the sheath 3 could be a PVC sheath.
  • the return conductor means is divided into three separate conductors 5a, 5b and 5c which are distributed in the cable core.
  • the return conductors means is constituted by two conductors 10 and 11 arranged 180 o apart whereas in Figure 3 there are three conductors 15, 16 and 17 arranged 120 o apart.
  • the return conductors 5 are arranged 90 o apart.
  • an earth wire 6 is arranged in a slot in the common insulation sheath 3
  • the earth conductor 20 is arranged as a group of conductors between the sheath 3 and the earth screen 7 and covering 10 - 25 % of the sheath surface.
  • All elements of the cable are preferably arranged in parallel with the cable axis, thereby avoiding stranding operations.

Landscapes

  • Resistance Heating (AREA)
  • Insulated Conductors (AREA)

Abstract

The present invention relates to electrical floor heating cable and in particular to cables generating acceptably small electromagnetic fields. The cable of the invention has a first, near end and a second, far end and comprises within an outer protective sheath (4) a cable core consisting of
  • a central resistance conductor (1)
  • a concentrical sheath of insulation material (2) surrounding the resistance conductor, - as well as
  • return conductor means (5) arranged to be interconnected with the resistance conductor in the far end of the cable.
The return conductor means consists of at least two separate conductors (5;5a-5c;10,11;15,16,17) which are distributed in the cable core. The return conductors are preferably embedded in a common insulation sheath (3) arranged over the resistance conductor sheath (2).

Description

The present invention relates to electrical floor heating cables and in particular to cables generating acceptably small electromagnetic fields. In general the magnetic field is best reduced/eliminated by a concentric shield, as in coaxial cables, but this is not a practical solution with heating cables. The field generation problem can also be somewhat reduced by using two-conductor cables instead of single-conductor cables because the fields generated from the two conductors tend to eliminate each other. The fields from two-conductor cables having a resistance conductor and a return conductor should - however - be further reduced.
The object of the present invention is to reduce the field generating properties of electrical floor heating cable having a first, near end and a second, far end and comprising within an outer protective sheath a cable core consisting of
  • a central resistance conductor,
  • a concentrical sheath of insulation material surrounding the resistance conductor, - as well as
  • return conductor means arranged to be interconnected with the resistance conductor in the far end of the cable.
The main features of the invention appears from the accompanying claims. The problem of eliminating or greatly reducing generation of electromagnetic fields which could be harmful to human beings occupying rooms heated with electrical floor heating cables has been solved by letting the return conductor means consist of at least two separate conductors which are distributed in the cable core. The electromagnetic field is reduced to about 1% of the field experienced from single conductor heating cables, and to some 10% of the fields from normal two conductor cables.
Above mentioned and other features and objects of the present invention will clearly appear from the following detailed description of embodiments of the invention taken in conjunction with the drawings, where
  • Figures 1-4 show four embodiments of the invention.
    • In Figure 1 to 4 a resistance conductor 1 is provided with a concentrical sheath 2 of insulation material such as crosslinked polyethylene. All embodiments have an outer protective sheath 4 of PVC or other suitable material and an earth screen 7 in contact with earth means 6 or 20. The earth screen could be a conventional Al/PE tape in contact with Cu wires 6 or 20. In the near end of the cable the resistance conductor can be substituted with a cold end copper conductor. Return conductors 5;10,11;15,16,17 are embedded in a common insulation sheath 3 arranged over the resistance conductor sheath 2. The sheath 3 could be a PVC sheath.
    In Figure 1 the return conductor means is divided into three separate conductors 5a, 5b and 5c which are distributed in the cable core. In Figure 2 the return conductors means is constituted by two conductors 10 and 11 arranged 180o apart whereas in Figure 3 there are three conductors 15, 16 and 17 arranged 120o apart. In Figure 4 the return conductors 5 are arranged 90o apart.
    In Figures 1-3 an earth wire 6 is arranged in a slot in the common insulation sheath 3, whereas in Figure 4 the earth conductor 20 is arranged as a group of conductors between the sheath 3 and the earth screen 7 and covering 10 - 25 % of the sheath surface.
    All elements of the cable are preferably arranged in parallel with the cable axis, thereby avoiding stranding operations.
    The above detailed description of embodiments of this invention must be taken as examples only and should not be considered as limitations on the scope of protection.

    Claims (10)

    1. Electrical floor heating cable having a first, near end and a second, far end and comprising within an outer protective sheath (4) a cable core consisting of
      a central resistance conductor (1),
      a concentrical sheath of insulation material (2) surrounding the resistance conductor, - as well as
      return conductor means (5) arranged to be interconnected with the resistance conductor in the far end of the cable, characterized in that
      the return conductor means consists of at least two separate conductors (5;5a-5c;10,11;15,16,17) which are distributed in the cable core.
    2. Cable according to claim 1,
      characterized in that the return conductors (5;5a-5c;10,11;15,16,17) are embedded in a common insulation sheath (3) arranged over the resistance conductor sheath (2).
    3. Cable according to claim 1 or 2,
      characterized in that the return conductors (5;5a-5c;10,11;15,16,17) are arranged in contact with the resistance conductor sheath (2).
    4. Heating cable according to claim 1, 2 or 3
      characterized in that the return conductors (5;10,11;15,16,17) are evenly distributed around the resistance conductor sheath, such as two conductors 180o apart or three conductors 120o apart or four conductors (5) 90o apart.
    5. Cable according to claim 1, 2 or 3,
      characterized in that the return conductors include three conductors (5a,5b,5c) arranged 90 degrees apart from each other and from an earth wire (6).
    6. Cable according to claim 2,
      characterized in that the common insulation sheath (3) is provided with slot (8) for receiving an earth wire (6) which is in contact with an earth screen (7).
    7. Cable according to claim 2,
      characterized in that it includes a number of earth wires (20) arranged around the common insulation sheath (3) in contact with an earth screen (7).
    8. Cable according to claim 7,
      characterized in that the earth wires (29) are arranged as a group around the sheath (3) covering 10 - 25 % of the sheath surface.
    9. Cable according to claim 1,
      characterized in that all the elements of the cable are arranged in parallel with the cable axis.
    10. Cable according to claim 1,
      characterized in that in the near end of the cable the resistance conductor is substituted with a cold end copper conductor.
    EP19970120263 1997-02-06 1997-11-19 Field free electrical floor heating cable Expired - Lifetime EP0858244B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    NO970531A NO304000B1 (en) 1997-02-06 1997-02-06 Heating cable
    NO970531 1997-02-06

    Publications (3)

    Publication Number Publication Date
    EP0858244A2 true EP0858244A2 (en) 1998-08-12
    EP0858244A3 EP0858244A3 (en) 1998-09-30
    EP0858244B1 EP0858244B1 (en) 2003-01-22

    Family

    ID=19900351

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP19970120263 Expired - Lifetime EP0858244B1 (en) 1997-02-06 1997-11-19 Field free electrical floor heating cable

    Country Status (4)

    Country Link
    EP (1) EP0858244B1 (en)
    DE (1) DE69718614T2 (en)
    NO (1) NO304000B1 (en)
    PL (1) PL324632A1 (en)

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US7388173B2 (en) 2004-12-27 2008-06-17 Nexans Heating cable

    Citations (6)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    FR2519505A1 (en) * 1981-12-31 1983-07-08 Thomson Jeumont Cables Earthing screen for electrical resistance heating wire - being combination of conductive wire and annular strip
    EP0383152A2 (en) * 1989-02-11 1990-08-22 Wilhelm Wetzel Gmbh + Co. Flexible electric heating apparatus
    WO1992008036A1 (en) * 1990-10-30 1992-05-14 Semen Zinovievich Erukhimovich Device to eliminate and prevent deposition of paraffin and hydrates in wells
    JPH07176372A (en) * 1993-12-21 1995-07-14 Mitsubishi Cable Ind Ltd Heating cable and heating unit
    DE29613341U1 (en) * 1996-08-01 1996-09-19 Wilhelm Friedrich Current conductor and plug connectable with this
    WO1997017707A1 (en) * 1995-11-07 1997-05-15 Il Young Pak Cord and heating wire

    Patent Citations (6)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    FR2519505A1 (en) * 1981-12-31 1983-07-08 Thomson Jeumont Cables Earthing screen for electrical resistance heating wire - being combination of conductive wire and annular strip
    EP0383152A2 (en) * 1989-02-11 1990-08-22 Wilhelm Wetzel Gmbh + Co. Flexible electric heating apparatus
    WO1992008036A1 (en) * 1990-10-30 1992-05-14 Semen Zinovievich Erukhimovich Device to eliminate and prevent deposition of paraffin and hydrates in wells
    JPH07176372A (en) * 1993-12-21 1995-07-14 Mitsubishi Cable Ind Ltd Heating cable and heating unit
    WO1997017707A1 (en) * 1995-11-07 1997-05-15 Il Young Pak Cord and heating wire
    DE29613341U1 (en) * 1996-08-01 1996-09-19 Wilhelm Friedrich Current conductor and plug connectable with this

    Non-Patent Citations (2)

    * Cited by examiner, † Cited by third party
    Title
    "Anschlußfertiges, schutzgeerdetes und einseitig verlegbares Heizkabel" ELEKTROTECHNIK, 19 September 1974, XP002069377 *
    PATENT ABSTRACTS OF JAPAN vol. 095, no. 010, 30 November 1995 & JP 07 176372 A (MITSUBISHI CABLE IND LTD), 14 July 1995, *

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US7388173B2 (en) 2004-12-27 2008-06-17 Nexans Heating cable

    Also Published As

    Publication number Publication date
    NO970531L (en) 1998-08-07
    EP0858244B1 (en) 2003-01-22
    DE69718614T2 (en) 2003-05-22
    NO304000B1 (en) 1998-10-05
    EP0858244A3 (en) 1998-09-30
    DE69718614D1 (en) 2003-02-27
    PL324632A1 (en) 1998-08-17
    NO970531D0 (en) 1997-02-06

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