EP0742565A2 - Elektronikdraht und Kabel mit wenige Paaren - Google Patents

Elektronikdraht und Kabel mit wenige Paaren Download PDF

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Publication number
EP0742565A2
EP0742565A2 EP96303088A EP96303088A EP0742565A2 EP 0742565 A2 EP0742565 A2 EP 0742565A2 EP 96303088 A EP96303088 A EP 96303088A EP 96303088 A EP96303088 A EP 96303088A EP 0742565 A2 EP0742565 A2 EP 0742565A2
Authority
EP
European Patent Office
Prior art keywords
communication cable
cable
polyvinyl chloride
parts
fire retardant
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.)
Withdrawn
Application number
EP96303088A
Other languages
English (en)
French (fr)
Other versions
EP0742565A3 (de
Inventor
Larry Lynn Bleich
Warren Freeman Moore
Tommy Glenn Hardin
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.)
AT&T Corp
Original Assignee
AT&T Corp
AT&T IPM Corp
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 AT&T Corp, AT&T IPM Corp filed Critical AT&T Corp
Publication of EP0742565A2 publication Critical patent/EP0742565A2/de
Publication of EP0742565A3 publication Critical patent/EP0742565A3/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29—Protection against damage caused by extremes of temperature or by flame
    • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame

Definitions

  • This invention relates to low pair count telecommunications cables having flame and smoke retardant characteristics and, more particularly, to a Category 3 cable for use in building interiors.
  • the increase in the use of computers and associated peripheral equipment, as well as numerous other electronic devices, in offices and other facilities has given rise to a need for electrical cable and associated wires to connect the various pieces of apparatus into a common network.
  • the cable should satisfy numerous requirements as to electrical performance and physical characteristics. Two of the most important requirements are that the cable be capable of substantially error free transmission at relatively high rates over substantial distances, and that it be flame retardant, especially where the cable is to be used in building plenums.
  • the room ceiling on each floor is usually spaced below the structural floor panel of the next higher floor and is referred to as a drop ceiling.
  • This spacing creates a return air plenum for the buildings heating and cooling systems, which is usually continuous throughout the entire length and breadth of the floor. If a fire occurs within a room or rooms on a floor and below the drop ceiling, it may be contained by the walls, ceiling, and floor of the room. On the other hand, if the fire reaches the plenum, it can spread at an alarming rate.
  • the plenum is a convenient place to route wires and cables, both electrical power and communications types. However, unless these wires and cables are flame retardant, they can contribute to the rapid spread of fire and smoke throughout the floor and, worse, throughout the building.
  • the National Electric Code prohibits the use of electrical cables in plenums unless they are enclosed in metal conduits.
  • metal conduits are difficult to route in plenums congested with other items or apparatus, and where, for example, it is desirable or necessary to rearrange the office and its communications equipment, computers, and the like, the re-routing of the conduits can become prohibitively expensive.
  • the NEC permits certain exceptions to the conduit requirements. Where, for example, a cable is flame retardant, and produces acceptably low smoke, the conduit requirement is waived provided that the cable, in tests, meets or exceeds the code's requirements for flame retardation and smoke suppression. Such tests must be conducted by a competent authority such as the Underwriters Laboratory.
  • a fire resistant cable in which the individual wires of the core have a dual insulation system comprising an inner layer of suitable plastic material and an outer layer of flame retardant plastic material.
  • the insulation system has the desirable characteristics of low dissipation factor and low dielectric constant, and the jacket, which surrounds the core, comprises a flame retardant polyolefin material with a low dissipation factor and dielectric constant.
  • the dual insulation arrangement represents an additional cost increment, especially for low pair cables, and can, in some cases, lead to increased structural return loss (SRL).
  • LAN local area networks
  • equipment is commercially available that can transmit 16 megahertz signals over several hundred feet, e.g., 300 to 400 ft. Even at these distances, however, the desired transmission must be substantially error free, which, heretofore, has placed strict requirements on the materials used.
  • the aforementioned Cabling Standard TIA/EIA-568 includes lesser categories for use under less stringent electrical requirements, among which is Category 3, which includes cables intended for use in the frequency range from 750 khz to 16 MHz.
  • Category 3 cables are generally made of less costly materials than those of Category 5, and exhibit greater attenuation throughout the frequency range of use, as well as exhibiting poorer near end cross-talk (NEXT) performance.
  • the cables even with the cheaper materials, must still meet the requirements for a CMP rating for use in plenums.
  • a Category 3 cable, CMP rated which has reduced attenuation and NEXT without a material increase in cost, is to be desired.
  • An example of a state-of-the-art Category 3 CMP rated cable is one in which the wire insulation is polyvinyl chloride (PVC) having approximately 51 parts per 100 parts PVC of fire retardant and 15 parts per 100 parts of PVC of smoke suppressant, and the twisted pairs of insulated wires are jacketed with a commercially available smoke suppressed PVC jacket.
  • the material of the insulation has a maximum dielectric constant of approximately 5.0, a maximum dissipation factor of 0.07, and a density in the range of 1.57-1.63 gm/cc.
  • the minimum dynamic thermal stability of the material, in minutes, is approximately 15 which allows longer extrusion runs between clean-ups.
  • Such a material has proved to be reasonably satisfactory for Category 3 CMP rated cable. However, it is somewhat expensive (approximately 1.54 dollars/lb-vol), and the dielectric constant and dissipation factors are higher than is preferred.
  • the present invention is a 2 to 6 pair (normally 4 pairs) Category 3 EW&C (Electronic Wire and Cable) unshielded cable design that is CMP rated, and which uses an insulation material having lower dielectric constant and lower dissipation factor, with a consequent improvement in electrical performance compared to prior art cables.
  • the cable of the invention is less costly to produce.
  • an EW&C cable comprises a plurality, e.g., four, twisted pairs of insulated conductors or other suitable transmission media, each of which comprises an elongated conductor member encased in an approximately seven mil thick insulation of polyvinyl chloride material which has a low dissipation factor, typically less than 0.05 at 1 MHz, and a maximum dielectric constant of approximately 3.8 radians.
  • the material has a density, in grams per cubic centimeter, of 1.31 to 1.38.
  • the PVC composition contains 0.5 to 3.0 parts antimony trioxide fire retardant; and approximately 0.5 to 1.5 parts of Ongard 2® smoke suppressant, which is a commercially available material.
  • the four twisted pairs are enclosed in a jacket of a commercially available fire retardant PVC material, approximately fifteen mils thick, such as Smokeguard II 6920 produced by the AlphaGary Corporation.
  • the twisted pairs are layless, i.e., they are not stranded together into a core before jacketing, and no filler material or core member is used.
  • the cable of the invention passes the UL 910 plenum burn test, thus satisfying the requirements for a TIA/EIA 568 Category 3 CMP rating.
  • the cable of the invention meets all of the required standards while, at the same time, is made of less expensive materials, is cheaper to manufacture, and yields an electrical performance that is superior to the prior art Category 3 CMP rated cables generally in use at the present time.
  • Figs. 1 and 2 there is shown, in a perspective view, the EW&C Category 3 low pair CMP rated cable 11 embodying the principles of the present invention, and having four twisted pairs of insulated conductors 12, 13, 14 and 16. It is to be understood that the number of twisted pairs may vary between two and six, the four shown in Figs. 1 and 2 being by way of example only. As can be seen, the pairs are grouped within, and surrounded by, a jacket 17.
  • Each of the conductors of each of the twisted pairs comprises a metallic, preferably copper, conducting wire portion 18 encased in insulating portion 19, which will be discussed more fully hereinafter.
  • the insulation 19 is approximately seven (7) mils thick, whereas most prior art twisted pair insulation for use in cables is eight (8) or more mils thick.
  • the electrical characteristics of the insulating material such as resistance, dielectric constant, dissipation factor and the like affect the electrical performance of the cable, as a general rule a thin insulation coating is better than a thicker one.
  • the jacket 17, enclosing the twisted pairs 12, 13, 14, and 16 is approximately fifteen (15) mils thick and is made of a commercially available, flame retardant, smoke suppressed PVC material such as, for example, Smokeguard II 6920® produced by AlphaGary Corporation.
  • the wire insulation material is PVC
  • the jacket material is also PVC
  • both the insulation and the jacket had to be flame retardant and smoke suppressed, with a flame retardant material surrounding the core and insulated wires inside the jacket for the cable to qualify as a CMP rated cable.
  • Applicants have found, however, that a combination of an improved insulating material, designated AT&T type 648B PVC, which has minimal flame retardant and smoke suppressant content, and a jacket of the aforementioned Smokeguard II 6920® yields both electrical and physical results such that the cable readily qualifies as a Category 3 CMP rated cable, contrary to all expectations based upon prior art cable research.
  • Fig. 3 there is shown a comparison table between the insulation material of the invention and a typical, widely used PVC insulation material for a CMP rated cable. It can be seen from the comparison, that the insulation material of the invention has thirty parts by weight per one hundred parts PVC of plasticizer, whereas the prior art material has thirty-eight parts of fire-retardant plasticizers. In addition, the material used in the present invention has only one part fire retardant and one part smoke suppressant whereas the prior art material has thirteen parts fire retardant and fifteen parts smoke suppressant. As a direct result of these differences in the composition of the insulation materials, the physical and electrical characteristics also differ to an important extent. Thus, from Fig.
  • the dielectric constant of the PVC insulation of the cable of the invention is a maximum of 3.8 radians, whereas that of the prior art material is a maximum of 5.0 radians.
  • the dielectric constant directly affects the transmission performance of the wires, and hence, the cable, and the lower it is, the better.
  • the maximum dissipation factor of the prior art cable insulation, in dimensionless units is approximately 0.07, whereas for the material of the cable of the invention it is approximately 0.05. This too is a case where the lower the figure, the better the electrical performance. Further examination of the table of Fig.

Landscapes

  • Insulated Conductors (AREA)
  • Communication Cables (AREA)
EP96303088A 1995-05-12 1996-05-01 Elektronikdraht und Kabel mit wenige Paaren Withdrawn EP0742565A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US44042995A 1995-05-12 1995-05-12
US440429 1995-05-12

Publications (2)

Publication Number Publication Date
EP0742565A2 true EP0742565A2 (de) 1996-11-13
EP0742565A3 EP0742565A3 (de) 1998-06-17

Family

ID=23748727

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96303088A Withdrawn EP0742565A3 (de) 1995-05-12 1996-05-01 Elektronikdraht und Kabel mit wenige Paaren

Country Status (1)

Country Link
EP (1) EP0742565A3 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103258594A (zh) * 2012-02-16 2013-08-21 尼克桑斯公司 具有聚氯乙烯交叉填充物的局域网电缆

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5173960A (en) * 1992-03-06 1992-12-22 At&T Bell Laboratories Cable having superior resistance to flame spread and smoke evolution
EP0710962A1 (de) * 1994-11-04 1996-05-08 AT&T Corp. Flammwidriges Kabel zur Verwendung in einem Kabelnetz
WO1996025748A1 (en) * 1995-02-15 1996-08-22 Alphagary Corporation Flame retardant and smoke suppressant composite electrical insulation, insulated electrical conductors and jacketed plenum cable formed therefrom

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5173960A (en) * 1992-03-06 1992-12-22 At&T Bell Laboratories Cable having superior resistance to flame spread and smoke evolution
EP0710962A1 (de) * 1994-11-04 1996-05-08 AT&T Corp. Flammwidriges Kabel zur Verwendung in einem Kabelnetz
WO1996025748A1 (en) * 1995-02-15 1996-08-22 Alphagary Corporation Flame retardant and smoke suppressant composite electrical insulation, insulated electrical conductors and jacketed plenum cable formed therefrom

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103258594A (zh) * 2012-02-16 2013-08-21 尼克桑斯公司 具有聚氯乙烯交叉填充物的局域网电缆
EP2629309A3 (de) * 2012-02-16 2013-12-04 Nexans LAN-Kabel mit PVC-Kreuzzwickel
US9842672B2 (en) 2012-02-16 2017-12-12 Nexans LAN cable with PVC cross-filler
CN103258594B (zh) * 2012-02-16 2018-01-23 尼克桑斯公司 具有聚氯乙烯交叉填充物的局域网电缆

Also Published As

Publication number Publication date
EP0742565A3 (de) 1998-06-17

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