CA2196485A1 - Telecommunications cable - Google Patents
Telecommunications cableInfo
- Publication number
- CA2196485A1 CA2196485A1 CA 2196485 CA2196485A CA2196485A1 CA 2196485 A1 CA2196485 A1 CA 2196485A1 CA 2196485 CA2196485 CA 2196485 CA 2196485 A CA2196485 A CA 2196485A CA 2196485 A1 CA2196485 A1 CA 2196485A1
- Authority
- CA
- Canada
- Prior art keywords
- cable
- inner layer
- jacket
- conductors
- insulation
- 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.)
- Abandoned
Links
Landscapes
- Organic Insulating Materials (AREA)
- Insulated Conductors (AREA)
Abstract
A telecommunications cable of the present invention includes a jacket having an inner layer and an outer layer. The inner layer is formed of a material having desired electrical properties, such as polyvinylchloride or fire retardant polyolefin. The outer layer is formed of a material having desired flame retardant properties, such as polyvinylidene fluoride. The conductors of the cable core can be insulated using a variety of materials selected principally for their electrical properties.
Description
21 9~485 I
TELECOMMUNICATIONS CABLE
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to a telecommunications cable for use in plenums. More particularly, it relates to a cable having a two part jacket and has sufficient fire retardancy characteristics for use in plenums and sufficient electrical properties for efficient use as a high capacity telecommunications cable.
o 2. Discussion of Related Art Telecommunications cable designs vary according to the role which the cables are meant to fulfill. In designing a cable, it is important to take every reasonable precaution to resist the spread of flame and the generation of and spread of smoke throughout a building in case of an outbreak of fire. This clearly is a main aim as s protection against loss of life and also to minimize the costs of the fire in relation to the destruction of electrical and other equipment. With this in mind, when cable is designed for installation in plenum chambers of air circulation systems in buildings, care needs to be taken to ensure that the cables have maximum resistance to flame spread, which prevents a fire from passing along a cable to other parts of a building. Care also needs o to be taken to produce minimum amounts of smoke when the cable burns, which reduces the chances of visibility becoming obscured, and thereby greatly increasing the chances of people within the building finding their way to safety.
Typically, cables have a plurality of wires comprised of a conductor surrounded by an insulation. The wires are also bundled together in a jacket of a dielectric material.
Unfortunately, many insulating materials are flammable or produce significant smoke when burned. On the other hand, insulating materials with low flammability and smoke characteristics tend to adversely affect the electrical transmission properties of the wires. This prevents many materials from being used in cables for communications, particularly for high data rates.
Conventional designs of data grade telecommunications cables for installation inplenum chambers use a low smoke generating jacket material, e.g. a formulation of PVC or of fluoropolymer material, surrounding a core of twisted conductor pairs, each conductor individually insulated with a fluorinated ethylene propylene (FEP) insulation layer. The latter material exhibits excellent flame retardant, smoke retardant and good electrical properties, and which is capable of satisfying certain recognized plenum test requirements. These include tests such as the "peak smoke," "average smoke," ands "flame spread" requirements of the UL910 Steiner test and/or CSAFT6 (Plenum Flame Test) while enabling the cable to achieve a desired electrical performance underrecognized test requirements ElAtTlA-568 and TSB-36 for high frequency signal transmission.
While the above-described cable is capable of meeting all of the above design criteria, use of fluorinated ethylene propylene is very expensive and may account for up to 60% of the cost of a cable designed for plenum usage.
Various cable designs have been developed to reduce the amount of FEP
needed, while maintaining the fire retardancy and electrical properties of the cable. In one such design NordxtCDT, for which a patent application is currently pending, a 15 telecommunications cable has a cable core in which the electrical conductors which are individually insulated with a dual layer insulation, each have an inner layer of a flame retardant polyolefin and an outer layer of fluorinated ethylene propylene surrounding the inner layer, the core being provided with a jacket of low smoke generating material.
The inner layer of the insulation has a volume of at least 30% of the total volume of the ~o dual insulation layer. This cable has been found to be suitable for in-plenum chamber usage. Even with these reductions in the amount of fluorinated ethylene propylene in a cable, it would be useful to have other constructions or materials which could have similar electrical transmission properties with further reductions in, or the entire elimination of, fluorinated ethylene propylene.
2s SUMMARY OF THE INVENTION
The present invention provides a telecommunications cable which is suitable for plenum chamber usage while providing a construction which may, if required, avoid the necessity of using fluorinated ethylene propylene in its entirety from the conductor 30 insulation.
According to one aspect of the invention, the present invention provides a 93691 . I
TELECOMMUNICATIONS CABLE
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to a telecommunications cable for use in plenums. More particularly, it relates to a cable having a two part jacket and has sufficient fire retardancy characteristics for use in plenums and sufficient electrical properties for efficient use as a high capacity telecommunications cable.
o 2. Discussion of Related Art Telecommunications cable designs vary according to the role which the cables are meant to fulfill. In designing a cable, it is important to take every reasonable precaution to resist the spread of flame and the generation of and spread of smoke throughout a building in case of an outbreak of fire. This clearly is a main aim as s protection against loss of life and also to minimize the costs of the fire in relation to the destruction of electrical and other equipment. With this in mind, when cable is designed for installation in plenum chambers of air circulation systems in buildings, care needs to be taken to ensure that the cables have maximum resistance to flame spread, which prevents a fire from passing along a cable to other parts of a building. Care also needs o to be taken to produce minimum amounts of smoke when the cable burns, which reduces the chances of visibility becoming obscured, and thereby greatly increasing the chances of people within the building finding their way to safety.
Typically, cables have a plurality of wires comprised of a conductor surrounded by an insulation. The wires are also bundled together in a jacket of a dielectric material.
Unfortunately, many insulating materials are flammable or produce significant smoke when burned. On the other hand, insulating materials with low flammability and smoke characteristics tend to adversely affect the electrical transmission properties of the wires. This prevents many materials from being used in cables for communications, particularly for high data rates.
Conventional designs of data grade telecommunications cables for installation inplenum chambers use a low smoke generating jacket material, e.g. a formulation of PVC or of fluoropolymer material, surrounding a core of twisted conductor pairs, each conductor individually insulated with a fluorinated ethylene propylene (FEP) insulation layer. The latter material exhibits excellent flame retardant, smoke retardant and good electrical properties, and which is capable of satisfying certain recognized plenum test requirements. These include tests such as the "peak smoke," "average smoke," ands "flame spread" requirements of the UL910 Steiner test and/or CSAFT6 (Plenum Flame Test) while enabling the cable to achieve a desired electrical performance underrecognized test requirements ElAtTlA-568 and TSB-36 for high frequency signal transmission.
While the above-described cable is capable of meeting all of the above design criteria, use of fluorinated ethylene propylene is very expensive and may account for up to 60% of the cost of a cable designed for plenum usage.
Various cable designs have been developed to reduce the amount of FEP
needed, while maintaining the fire retardancy and electrical properties of the cable. In one such design NordxtCDT, for which a patent application is currently pending, a 15 telecommunications cable has a cable core in which the electrical conductors which are individually insulated with a dual layer insulation, each have an inner layer of a flame retardant polyolefin and an outer layer of fluorinated ethylene propylene surrounding the inner layer, the core being provided with a jacket of low smoke generating material.
The inner layer of the insulation has a volume of at least 30% of the total volume of the ~o dual insulation layer. This cable has been found to be suitable for in-plenum chamber usage. Even with these reductions in the amount of fluorinated ethylene propylene in a cable, it would be useful to have other constructions or materials which could have similar electrical transmission properties with further reductions in, or the entire elimination of, fluorinated ethylene propylene.
2s SUMMARY OF THE INVENTION
The present invention provides a telecommunications cable which is suitable for plenum chamber usage while providing a construction which may, if required, avoid the necessity of using fluorinated ethylene propylene in its entirety from the conductor 30 insulation.
According to one aspect of the invention, the present invention provides a 93691 . I
telecommunications cable having a core comprising a plurality of pairs of individually insulated conductors and a jacket surrounding the core, the jacket having an inner layer and an outer layer, the inner layer provided by a material which provides desired electrical characteristics to the cable, and the outer layer comprising polyvinylidene s fluoride.
According to another aspect of the invention, the inner layer of a telecommunications cable may be any desirable material to provide the required electrical performance. Such materials, including polyvinylchloride materials, may have their own fire retardancy performance. Alternatively, the inner layer may comprise non-o halogenated fire retardant polyolefin materials.
According to another aspect of the invention, various types of conductor insulation may be used in different combinations as required. For instance, in atelecommunications cable having four pairs of individually insulated conductors,insulation of conductors on two pairs may be entirely formed from fluorinated ethylene propylene and the insulation on the other two pairs of fire retardant polyolefins, such as polyethylene, polypropylene or mixture of these materials. Alternatively, only one pair of conductors may have insulation formed of fire retardant polyolefin material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of part of a telecommunications cable according to an embodiment of the present invention; and FIG. 2 is a cross-sectional view through the cable of Figure 1.
DETAILED DESCRIPTION
FIGS 1 and 2 illustrate a telecommunications cable 10 suitable for high performance data transmission in plenum chamber situations. The cable 10 includes a cable core 12 and a dual layer cable jacket 16.
As illustrated, the cable core 12 is formed by four twisted pairs of conductors 14.
Of course, different numbers of conductors are possible. Each of the conductors 14 of 30 the cable core 12 is individually insulated. Different insulations may be used for the conductors. In particular, insulation may be selected as desired for plenum usage.
93691 . I
According to another aspect of the invention, the inner layer of a telecommunications cable may be any desirable material to provide the required electrical performance. Such materials, including polyvinylchloride materials, may have their own fire retardancy performance. Alternatively, the inner layer may comprise non-o halogenated fire retardant polyolefin materials.
According to another aspect of the invention, various types of conductor insulation may be used in different combinations as required. For instance, in atelecommunications cable having four pairs of individually insulated conductors,insulation of conductors on two pairs may be entirely formed from fluorinated ethylene propylene and the insulation on the other two pairs of fire retardant polyolefins, such as polyethylene, polypropylene or mixture of these materials. Alternatively, only one pair of conductors may have insulation formed of fire retardant polyolefin material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of part of a telecommunications cable according to an embodiment of the present invention; and FIG. 2 is a cross-sectional view through the cable of Figure 1.
DETAILED DESCRIPTION
FIGS 1 and 2 illustrate a telecommunications cable 10 suitable for high performance data transmission in plenum chamber situations. The cable 10 includes a cable core 12 and a dual layer cable jacket 16.
As illustrated, the cable core 12 is formed by four twisted pairs of conductors 14.
Of course, different numbers of conductors are possible. Each of the conductors 14 of 30 the cable core 12 is individually insulated. Different insulations may be used for the conductors. In particular, insulation may be selected as desired for plenum usage.
93691 . I
Furthermore, the conductors can be selected for desired transmission capabilities. For example, an insulation of a fire retardant polyolefin of suitable thickness may be placed upon a 24 AWG copper conductor to provide the desired electrical and transmission performance. The insulation does not need to be identical for all of the conductors 14 s in the core 12. Additional combinations or layers of insulation may also be used on the conductors. For example, one or more of the conductors may be insulated with FEF', while the remaining conductors have a fire retardant polyolefin. The insulation on the conductors may also be foFmed in multiple layers.
The cable jacket 16 surrounds the core 12 and has an inner layer 18 and outer o layer 20. The two layers are formed of different materials having different properties.
The inner layer 18 is formed of a material having desireable electrical properties and assists in the required electrical, transmission, attenuation and impedance characteristics required for a telecommunications cable. The outer layer 20 is formed of a material having desireable fire retardancy and smoke production characteristics, while 15 possibly not having suffficiently desireable electrical properties.
According to an embodiment of the present invention, the inner layer 18 is formed of a polyvinylchloride composition. The polyvinylchloride composition also provides some flame spread retardant characteristics and low smoke generation characteristics. These characteristics are, however, provided primarily in this cable by 20 the outer layer 20 formed from a polyvinylidene fluoride material. A polyvinylidene fluoride copolymer is sold by Solvay under the trade names SOLEF 31508/0009T or 32008/0009T. These particular materials are flexible, have a very high LOI and very low smoke generation which is lower than that provided by polyvinylchloride compositions. These materials are incapable of assisting substantially in any way to 25 improve the electrical, transmission, or attenuation and impedance characteristics of the cable since they have unsuitable dielectric properties. These poor dielectric properties are counterbalanced by the other materials of the inner cable jacket and cable core.
The use of a dual jacket using an outer layer of Solef material has such excellent fire retardant and low smoke generating characteristics that, when of a suitable thickness, 30 the individual insulation for each of the conductors is itself relieved of at least some of its responsibility to produce low flame retardant and low smoke generation 9369 1 . I
- 21 ~6485 characteristics. Thus, fluorinated ethylene propylene may be avoided altogether for the conductor insulation. as mentioned above.
In one embodiment, the cable jacket 16 has inner 18 and outer 20 layers, respectively of polyvinylchloride and polyvinylidene fluoride, each of 10 mil thickness.
s In this embodiment, the individual conductors of the four pairs may all be insulated with a material which is specified mainly or entirely for its electrical transmission, attenuation and impedance properties. In this particular case as indicated above, this insulation may be entirely in the form of a fire retardant polyolefin. Such a construction meets the "peak smoke," "average smoke," and "flame spread" requirements of the o UL910/CSAFT6 (Plenum Flame Test) and has the desired electrical performance requirements of EIA/TIA-568 and TSB-36 for high frequency signal transmission.
Of course, different materials may be used in the inner layer 18 and outer layer20 of the cable jacket 20. For example, the inner layer may be formed of a non-halogenated fire retardant polyolefin. However, the inner layer 18 provides the 5 electrical properties, while the outer layer 20 provides most of the flame retardant properties. Also, different thicknesses of the layers may be used. Of course, the particular materials and thicknesses need to be selected to provide the desired electrical and flame retardant capabilities for the intended use. Various combinations of materials and thicknesses have been tested with similar, but not quite as good, results 20 to the 10 mil layers of polyvinylchloride and polyvinylidene fluoride, as shown in Table 1. Of course, the electrical and flame retardant properties of the cable can also be changed by the selection of the material in the cable core 12.
Polyvinylchloride Polyvinylidene Fluoride Trade Name Thickness TradeThickness Name AlphaGary 15 mils Solef14 mils AlphaGary 15 mils Solef11 mils 93691 . I
The cable jacket 16 surrounds the core 12 and has an inner layer 18 and outer o layer 20. The two layers are formed of different materials having different properties.
The inner layer 18 is formed of a material having desireable electrical properties and assists in the required electrical, transmission, attenuation and impedance characteristics required for a telecommunications cable. The outer layer 20 is formed of a material having desireable fire retardancy and smoke production characteristics, while 15 possibly not having suffficiently desireable electrical properties.
According to an embodiment of the present invention, the inner layer 18 is formed of a polyvinylchloride composition. The polyvinylchloride composition also provides some flame spread retardant characteristics and low smoke generation characteristics. These characteristics are, however, provided primarily in this cable by 20 the outer layer 20 formed from a polyvinylidene fluoride material. A polyvinylidene fluoride copolymer is sold by Solvay under the trade names SOLEF 31508/0009T or 32008/0009T. These particular materials are flexible, have a very high LOI and very low smoke generation which is lower than that provided by polyvinylchloride compositions. These materials are incapable of assisting substantially in any way to 25 improve the electrical, transmission, or attenuation and impedance characteristics of the cable since they have unsuitable dielectric properties. These poor dielectric properties are counterbalanced by the other materials of the inner cable jacket and cable core.
The use of a dual jacket using an outer layer of Solef material has such excellent fire retardant and low smoke generating characteristics that, when of a suitable thickness, 30 the individual insulation for each of the conductors is itself relieved of at least some of its responsibility to produce low flame retardant and low smoke generation 9369 1 . I
- 21 ~6485 characteristics. Thus, fluorinated ethylene propylene may be avoided altogether for the conductor insulation. as mentioned above.
In one embodiment, the cable jacket 16 has inner 18 and outer 20 layers, respectively of polyvinylchloride and polyvinylidene fluoride, each of 10 mil thickness.
s In this embodiment, the individual conductors of the four pairs may all be insulated with a material which is specified mainly or entirely for its electrical transmission, attenuation and impedance properties. In this particular case as indicated above, this insulation may be entirely in the form of a fire retardant polyolefin. Such a construction meets the "peak smoke," "average smoke," and "flame spread" requirements of the o UL910/CSAFT6 (Plenum Flame Test) and has the desired electrical performance requirements of EIA/TIA-568 and TSB-36 for high frequency signal transmission.
Of course, different materials may be used in the inner layer 18 and outer layer20 of the cable jacket 20. For example, the inner layer may be formed of a non-halogenated fire retardant polyolefin. However, the inner layer 18 provides the 5 electrical properties, while the outer layer 20 provides most of the flame retardant properties. Also, different thicknesses of the layers may be used. Of course, the particular materials and thicknesses need to be selected to provide the desired electrical and flame retardant capabilities for the intended use. Various combinations of materials and thicknesses have been tested with similar, but not quite as good, results 20 to the 10 mil layers of polyvinylchloride and polyvinylidene fluoride, as shown in Table 1. Of course, the electrical and flame retardant properties of the cable can also be changed by the selection of the material in the cable core 12.
Polyvinylchloride Polyvinylidene Fluoride Trade Name Thickness TradeThickness Name AlphaGary 15 mils Solef14 mils AlphaGary 15 mils Solef11 mils 93691 . I
AlphaGary 12 milsSolef 11 mils AlphaGary 12milsAtochem 11 mils 6920F1 Kynar 2850 s AlphaGary 12 milsSolef 8 mils AlphaGary . 10 milsSolef 6 mils Vista Plenex 12 milsSolef 8 mils o 1280 Table 1 Having described several embodiments, the present invention is not limited to any specific disclosed embodiments. Those of ordinary skill in the art will readily recognize different modifications and variations which are part of this invention.
93691 .1
93691 .1
Claims (6)
1. A telecommunications cable comprising:
a conductive core comprising a plurality of pairs of individually insulated conductors; and a jacket surrounding the core, the jacket including an inner layer and an outer layer.
a conductive core comprising a plurality of pairs of individually insulated conductors; and a jacket surrounding the core, the jacket including an inner layer and an outer layer.
2. A telecommunications cable according to claim 1, wherein the inner layer is formed of a material having desired electrical characteristics for the cable.
3. A telecommunications cable according to claim 1, wherein the outer layer is formed of a material having desired flame retardance characteristics for the cable.
4. A telecommunications cable according to claim 3, wherein the outer layer is formed of polyvinylidene fluoride.
5. A cable according to claim 2, wherein the inner layer of the jacket formed of a polyvinylchloride composition.
6. A cable according to claim 2, wherein the inner layer is provided by a non-halogenated fire retardant polyolefin.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US79056597A | 1997-01-29 | 1997-01-29 | |
| US08/790,565 | 1997-01-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2196485A1 true CA2196485A1 (en) | 1998-07-29 |
Family
ID=25151087
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2196485 Abandoned CA2196485A1 (en) | 1997-01-29 | 1997-01-31 | Telecommunications cable |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2196485A1 (en) |
-
1997
- 1997-01-31 CA CA 2196485 patent/CA2196485A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |