U.S. patent number RE37,010 [Application Number 08/701,396] was granted by the patent office on 2001-01-09 for communication cable for use in a plenum.
This patent grant is currently assigned to Alcatel NA Cable Systems, Inc.. Invention is credited to Kerry Newmoyer.
United States Patent |
RE37,010 |
Newmoyer |
January 9, 2001 |
Communication cable for use in a plenum
Abstract
A communication cable includes a plurality of twisted pairs of
electrical conductors, each electrical conductor being surrounded
by a layer of plenum rated insulation. The cable also includes at
least one additional twisted pair of electrical conductors, each
electrical conductor thereof being surrounded by a layer of
non-plenum rated insulation.
Inventors: |
Newmoyer; Kerry (Denver,
PA) |
Assignee: |
Alcatel NA Cable Systems, Inc.
(Claremont, NC)
|
Family
ID: |
23321032 |
Appl.
No.: |
08/701,396 |
Filed: |
August 22, 1996 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
337564 |
Nov 10, 1994 |
05493071 |
Feb 20, 1996 |
|
|
Current U.S.
Class: |
174/113R;
174/110FC; 174/121A; 174/34 |
Current CPC
Class: |
H01B
7/295 (20130101) |
Current International
Class: |
H01B
7/295 (20060101); H01B 7/17 (20060101); H01B
011/02 () |
Field of
Search: |
;174/113R,107,121A,34,11FC |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Berk-Tek Product Specification, Drawing Number 230042, Part Number
BTTB-24-25D-P/HX, dated Aug. 12, 1987, pp. 1-3. .
Essex Group, Inc. Bullentin 2021-0391, Inside Premises Wiring,
1991. .
Underwriters Laboratories Inc., File E107869, Project 90ME13368,
Report on Communications Cable, Teledyne Thermatics, Elm City, NC,
Sep. 25, 1990. .
Underwriters Laboratories Inc., File E113333, vol. 1, Sec. 14,
Report on a Communication Cable, Issued Jul. 12, 1991, Revised Jan.
17, 1995, pp. 1-2. .
Teledyne Thermatics, Elm City, North Carolina, Type 2 Data &
Telephone Plenum Cable, Drawing No. 12632/3, dated May 16, 1990,
pp. 1-3. .
Champlain Cable Corp. News Release, Notice #4, dated Feb. 8, 1990.
.
Journal of Vinyl Technology, vol. 7, No. 3, Sep. 1985, pp. 107-111.
.
International Wire & Cable Symposium Proceedings 1987, Reduced
Emissions Plenum Cable Jacket Compounds, M. J. Keogh, pp. 592-597.
.
U.L. Report: File E 57891, vol. 1, Sec. 2, Issued Jan. 3, 1977,
Revised Jun. 22, 1992. .
U.L. Report: File E 57891, vol. 1, Sec. 3, Issued Feb. 25, 1971,
Revised Jun. 22, 1992. .
U.L. Report: File E 57891, vol. 1, Sec. 4, Revised Jun. 1, 1989.
.
Underwriter's Laboratory Standard 910 Paper..
|
Primary Examiner: Sough; Hyung-Sub
Assistant Examiner: Mayo, III; William H
Attorney, Agent or Firm: Ware, Fressola, Van Der Sluys &
Adolphson LLP
Claims
What is claimed is:
1. A communication cable for use in a plenum, said cable
comprising:
a plurality of twisted pairs of electrical conductors, each
electrical conductor of said plurality of twisted pairs having a
.Iadd.single .Iaddend.surrounding layer of electrical
insulation.Iadd., said single surrounding layer of electrical
insulation of each electrical conductor of said plurality of
twisted pairs being .Iaddend.formed from .[.a first material.].
.Iadd.fluoroethylenepropylene (FEP).Iaddend.;
at least one additional twisted pair of electrical conductor, each
electrical conductor of said at least one additional twisted pair
having a .Iadd.single .Iaddend.surrounding layer of electrical
insulation.Iadd., said single surrounding layer of electrical
insulation of each electrical conductor of said at least one
additional twisted pair being .Iaddend.formed from .[.a second
material, said second material being different from said first
material.]. .Iadd.an olefin.Iaddend..
.[.2. The communication cable as claimed in claim 1 wherein said
first material is a plenum rated insulation material..].
.[.3. The communication cable as claimed in claim 2 wherein said
second material is a modified non-plenum rated insulation
material..].
.[.4. The communication cable as claimed in claim 1 wherein said
second material is a modified non-plenum rated insulation
material..].
.[.5. The communication cable as claimed in claim 4 wherein said
second material is an olefin..].
6. The communication cable as claimed in claim 1 wherein said
.[.second material.]. .Iadd.olefin .Iaddend.is a highly brominated
and antimony trioxide filled HDPE blended with HDPE.
7. The communication cable as claimed in claim 6 wherein said blend
is at a 50/50 ratio.
8. The communication cable as claimed in claim 6 wherein said blend
is at a 75/25 ratio.
9. The communication cable as claimed in claim .[.6.]. .Iadd.1
.Iaddend.wherein said .[.second material.]. .Iadd.olefin
.Iaddend.is a hydrated mineral filled polyolefin copolymer HDPE
.Iadd.blended with HDPE.Iaddend..
10. The communication cable as claimed in claim 9 wherein said
blend is at a 50/50 ratio.
11. The communication cable as claimed in claim 9 wherein said
blend is at a 75/25 ratio.
12. The communication cable as claimed in claim 1, further
comprising:
a cable jacket, said cable jacket encasing said plurality of
twisted pairs and said at least one additional twisted pair.
13. The communication cable as claimed in claim 12 wherein said
cable jacket is formed from ethylene-trichlorofluoroethylene.
14. The communication cable as claimed in claim 12 wherein said
cable jacket is formed from a polymer alloy.
15. The communication cable as claimed in claim 12 wherein said
cable jacket is formed from polyvinylchloride.
16. The communication cable as claimed in claim 1 wherein said
plurality of twisted pairs and said at least one additional twisted
pair of electrical conductors have different twist lengths.
17. The communication cable as claimed in claim 16 wherein said at
least one additional twisted pair has the shortest twist
length.
.[.18. The communication cable as claimed in claim 17 wherein said
second material includes an olefin base..].
19. The communication cable as claimed in claim .[.18.]. .Iadd.17
.Iaddend.wherein said .[.second material.]. .Iadd.olefin
.Iaddend.is a highly brominated and antimony trioxide filled
HDPE.
20. The communication cable as claimed in claim .[.18.]. .Iadd.17
.Iaddend.wherein said .[.second material.]. .Iadd.olefin
.Iaddend.is a hydrated mineral filled polyolefin copolymer
HDPE.
21. A communication cable for use in a plenum, said communication
cable comprising:
a first plurality of twisted pairs of electrical conductors having
a .[.first.]. .Iadd.single layer of .Iaddend.insulating material
about each electrical conductor thereof.Iadd., said single layer of
insulating material about each electrical conductor of said first
plurality of twisted pairs being fluoroethylenepropylene (FEP);
.Iaddend.and
a second plurality of twisted pairs of electrical conductors having
a .[.second.]. .Iadd.single layer of .Iaddend.insulating material
about each electrical conductor thereof, .Iadd.said single layer of
insulating material about each electrical conductor of said second
plurality of twisted pairs including an olefin base and
.Iaddend.said second plurality of twisted pairs making up no more
than half the total number of twisted pairs of electrical
conductors.
.[.22. The communication cable as claimed in claim 21 wherein said
first material is a plenum rated insulation material..].
.[.23. The communication cable as claimed in claim 22 wherein said
second material is a modified non-plenum rated insulation
material..].
.[.24. The communication cable as claimed in claim 21 wherein said
second material is a modified non-plenum rated insulation
material..].
.[.25. The communication cable as claimed in claim 24 wherein said
second material includes an olefin base..].
26. The communication cable as claimed in claim 21 wherein said
.[.second.]. .Iadd.olefin based insulating .Iaddend.material is a
highly brominated and antimony trioxide filled HDPE.
27. The communication cable as claimed in claim 21 wherein said
.[.second.]. .Iadd.olefin base insulating .Iaddend.material is a
hydrated mineral filled polyolefin copolymer HDPE.
28. The communication cable as claimed in claim 21, further
comprising:
a cable jacket, said cable jacket encasing said first plurality of
twisted pairs and said second plurality of twisted pairs.
29. The communication cable as claimed in claim 28 wherein said
cable jacket is formed from ethylene-trichlorofluoroethylene.
30. The communication cable as claimed in claim 28 wherein said
cable jacket is formed from a polymer alloy.
31. The communication cable as claimed in claim 28 where said cable
jacket is formed from polyvinylchloride.
32. The communication cable as claimed in claim 21 wherein said
first plurality of twisted pairs and said second plurality of
twisted pairs of electrical conductors have different twist
lengths.
33. The communication cable as claimed in claim 32 wherein said
second plurality of twisted pairs include the shortest twist
lengths..Iadd.
34. The communication cable as claimed in claim 1 wherein said
olefin is a hydrated mineral filled polyolefin in copolymer
HDPE..Iaddend..Iadd.
35. The communication cable as claimed in claim 34 wherein said
plurality of twisted pairs and said at least one additional twisted
pair of electrical conductors have different twist
lengths..Iaddend..Iadd.
36. A communication cable for use in a plenum, said communication
cable comprising:
a first plurality of twisted pairs of electrical conductors having
a single layer of insulating material about each electrical
conductor thereof, said single layer of insulating material about
each electrical conductor of said first plurality of twisted pairs
being formed from a first material; and
a second plurality of twisted pairs of electrical conductors having
a single layer of insulating material about each electrical
conductor thereof, said single layer of insulating material about
each electrical conductor of said second plurality of twisted pairs
being formed from a second material including an olefin base, and
said second plurality of twisted pairs making up no more than half
the total number of twisted pairs of electrical
conductors..Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to a communication cable
for use in a plenum and, in particular, relates to one such
communication cable having a first plurality of twisted pairs of
electrical conductors having a first insulating material about each
electrical conductor thereof and a second plurality of twisted
pairs of electrical conductors having a second insulating material
about each electrical conductor thereof.
As communications and communication services have increased, it has
become necessary to provide communication cables in larger and
larger numbers. This is particularly true in office buildings where
more and mores communication services are being demanded.
Typically, rather than rewire an existing building, it has been
found more economical to provide the needed communication services
by running the communication cables in plenums. In general, a
plenum is defined as a compartment or chamber to which one or more
air ducts are connected and which forms part of the air
distribution system. Generally, in existing buildings, plenums are
readily formed by providing drop ceilings, which is typically a
return air plenum, in a facility being rewired. Another alternative
is to create a plenum beneath a raised floor of a facility.
From the above it is readily understood why it would be very
advantageous to utilized a wiring scheme within these fairly
accessible places. However, since these plenums handle
environmental air, considerable concern regarding a fire incidence
is addressed in the National Electrical Code by requiring that
communications cables for use in plenums pass a stringent flame and
smoke evaluation. Consequently, in the manufacture of communication
cables the fire resistance ratings which allow for installation
within certain areas of a building are of primary importance.
Currently, communication cables for use in plenums must meet the
requirements of the Underwriter's Laboratory Standard 910 which is
a Test Method For Fore and Smoke Characteristics of Cables Used In
Air-Handling Spaces. This is a well known test performed in a
modified Steiner Tunnel. During the test, a single layer of 24 foot
lengths of cable more supported on a one foot wide cable rack which
is filled with cables. The cables are ignited with a 300,000 Btu/hr
methane flame located at one end of the furnace for a duration of
20 minutes. Flame spread is aided by a 240 ft/minute draft. Flame
spread is then monitored through observation windows along the side
of the tunnel while concurrently monitoring smoke emissions through
photocells installed within the exhaust duct. This is a severe test
that to date has been passed by communication cables using premium
materials such as low smoke materials, for example,
Fluroethylenepropylene (FEP), Ethylenechlorotrifluoroethylene
(ECTFE), or Polyvinylidene fluoride (PVDF), In general, cables
meeting this test are approximately three times more expensive than
a lower rated cable designed for the same application. However,
communication cables failing this test must be installed within
conduit, thereby eliminating the benefits of an economical, easily
relocatable cable scheme.
In general, the manufacture of communication cables are well known,
for example, U.S. Pat. No. 4,423,589, issued to Hardin et al. on
Jan. 3, 1984 discloses a method of manufacturing a communications
cable by forming a plurality of wire units by advancing groups of
twisted wire pairs through twisting stations. Further, U.S. Pat.
No. 4,446,689 issued to Hardin et al. On May 8, 1984 relates to an
apparatus for manufacturing a communications cable wherein disc
frames are provided with aligned apertures in which faceplates
movably mounted. During operation, the faceplates are modulated in
both frequency and amplitude.
The current materials for use in communications are also well
known, for example, U.S. Pat. No. 5,001,304 issued to Hardin et al.
on Mar. 19, 1991 relates to a building riser cable having a core
which includes twisted pairs of metal conductors. Therein the
insulating covers are formed from a group of materials including
polyolefin. It should be noted however, that all of the insulating
covers are the same and that the flame test used for riser cables
is much less severe than the flame test used for plenum cables.
U.S. Pat. No. 5,024,506 issued to Hardin et al. on Jun. 18, 1991
discloses a plenum cable that includes non-halogenated plastic
materials. The insulating material about the metallic conductors is
a polyetherimide. Again the insulating material is the same for all
of the conductors. Further, in U.S. Pat. No. 5,074,640 issued to
Hardin et al. On Dec. 24, 1991 a plenum cable is described that
includes an insulator containing a polyetherimide and an additive
system including an antioxidant/thermal stabilizer and a metal
deactuator. As is the convention, the insulator is the same for all
of the metallic conductors.
U.S. Pat. No. 5,202,946 issued to Hardin et al. on Apr. 13, 1993
describes a plenum cable wherein the insulation includes a plastic
material. The insulation is the same for all of the conductors
within the plenum cable. European Patent 0 380 245 issued to Hardin
et al. describes another plenum cable having insulation about the
metallic conductors that, in this case, is a plastic material
including a polyetherimide. As is the convention the insulation is
the same for all of the conductor.
Further, U.S. Pat. No. 4,491,729 describes a cable that is intended
as a low hazard cable. This patent describes a cable that includes
a non-halogenated plastic material. Similarly, U.S. Pat. No.
4,969,706 describes a cable that includes both halogenated and
non-halogenated plastic materials. In both patents the insulating
material about the twisted pairs of conductors is the same for each
cable.
U.S. Pat. No. 4,412,094 issued to Doughrety et al. on Oct. 25, 1983
relates to a riser cable having a composite insulator having an
inner layer of expanded polyethylene and an outer layer of a
plasticized polyvinyl chloride. All of the conductors include the
same composite insulator.
U.S. Pat. No. 4,500,748 issued to Klein on Feb. 19, 1985 relates to
a flame retardant plenum cable wherein the insulation and the
jacket are made from the same or different polymers to provide a
reduced amount of halogens. This reference tries to predict,
mathematically, the performance of cables within the Steiner
tunnel. The method does not include fuel contributions or
configurations of designs. Further, synergistic effects are not
addressed. In each embodiment, the insulation is the same for all
of the conductors.
U.S. Pat. No. 4,605,818 issued to Arroyo et al. on Aug. 12, 1986
relates to a flame retardant plenum cable wherein the conductor
insulation is a polyvinyl chloride plastic provided with a flame
retardant, smoke suppressive sheath system. As is common throughout
the known communication cables the conductor insulation is the same
for all of the conductors.
U.S. Pat. No. 4,678,294 issued to Angeles on Aug. 18, 1987 relates
to a fiber optic plenum cable. The optical fibers are provided with
a buffer layer surrounded by a jacket. The cable is also provided
with strength members for ridigity.
U.S. Pat. No. 5,010,210 issued to Sidi et al. on Apr. 23, 1991
describes a non-plenum telecommunications cable wherein the
insulation surrounding each of the conductors is formed from a
flame retardant polyolefin base compound.
U.S. Pat. No. 5,162,609 issued to Adriaenssens et al. on Nov. 10,
1992 relates to a fire-resistant non-plenum cable for high
frequency signals. Each metallic member has an insulation system.
The insulation system includes an inner layer of a polyolefin and
an outer layer of flame retardant polyolefin plastic.
U.S. Pat. No. 5,253,317 issued to Allen et al. on Oct. 12, 1993
describes a non-halogenated plenum cable including twisted pairs of
insulated metallic conductors. The insulating material is a
non-halogenated sulfone polymer composition. The insulating
material is the same for all of the metallic conductors.
It can thus be understood that much work has been dedicated to
providing not only communication cables that meet certain safety
requirements but meet electrical requirements as well.
Nevertheless, the most common communication cable that is in widest
use today includes a plurality of twisted pairs of electrical
conductors each having an insulation of FEP, which is a very high
temperature material and possesses those electrical
characteristics, such as, low dielectric constant and dissipation
factor, necessary to provide high quality communications cable
performance. However, FEP is quite expensive and is frequently in
short supply.
Consequently, the provision of a communication cable for use in
plenums but has a reduced cost and reduced use of FEP is highly
desired.
SUMMARY OF THE INVENTION
Accordingly, it is one object of the present invention to provide a
communication cable for use in a plenum which reduces the amount of
FEP or other expensive materials and hence, reduces the cost of the
communication cable.
This object is accomplished, at least in part by the a
communication cable that has a first plurality of twisted pairs of
electrical conductors having a first insulating material about each
electrical conductor thereof and a second plurality of twisted
pairs of electrical conductors having a second insulating material
about each electrical conductor thereof.
In one particular aspect of the invention, the communication cable
includes four twisted pairs of electrical conductors wherein the
electrical conductor of three of the four pairs are insulated with
a material that is a plenum rated material wherein the insulation
of the electrical conductors of the fourth pair is a modified
non-plenum rated insulation material. As used herein the phrase
"plenum rated insulation" includes those materials that would allow
a cable to pass standard industry plenum tests if it were used on
all of the twisted pairs of electrical conductors of a cable.
Correspondingly, the phrase "non-plenum rated" insulation includes
those materials that would significantly contribute to a cable
failing standard industry plenum tests if it were used on all of
the twisted pairs of electrical conductors of a cable. Typically,
these non-plenum materials provide too much fuel contribution to
the flame test either through a low melting point or a high fuel
content or a combination of these factors. Non-plenum materials may
also contribute excessively to the smoke generation of the cable
under test, thus rendering the cable unsuitable for plenum
applications. In such a communication cable the insulation material
can be an olefin which is a material usually reserved for use in
non-plenum application, for example, in riser cables.
In another aspect of the invention, the communication cable
includes a first plurality of twisted pairs of electrical
conductors wherein the insulation material of each of the first
plurality of twisted pairs of conductors is a material
conventionally used in plenum cables. In this aspect of the
invention, the communication cable also includes a second plurality
of twisted pairs of conductors having an insulation that is
different from the insulation of the first plurality of twisted
pairs of electrical conductors. The number of pairs in the second
plurality of twisted pairs being no greater than the number of
twisted pairs of the first plurality of electrical conductors.
Other objects and advantages will become apparent to those skilled
in the art from the following detailed description of the invention
read in conjunction with the appended claims and the drawings
attached hereto.
BRIEF DESCRIPTION OF THE DRAWING
The drawings, not drawn to scale, include:
FIG. 1 which is a perspective view of a communication cable
embodying the principles of the present invention; and
FIG. 2 which is an end view of another communication cable also
embodying the principles of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A communication cable, generally indicated at 10 in FIG. 1 and
embodying the principles of the present invention, includes a
plurality of twisted pairs 12 of electrical conductors each member
14 of the twisted pairs 12 being surrounded by a layer 16 of
insulation material and at least one other twisted pair 18 of
electrical conductors each member 20 thereof surrounded by a layer
22 of insulation material that is different from the material of
the layer 16 of insulation material of the twisted pairs 12. In one
preferred embodiment, the plurality of twisted pairs 12 and the
twisted pair 18 are surrounded by a cable jacket 24.
In one particular embodiment, each of the twisted pairs, 12 and 18,
is provided with a twist length. In an embodiment wherein the
communication cable 10 includes four twisted pairs, one or two of
the twisted pairs are twisted pairs be having a layer 22 of
insulation material different from the other twisted pairs 12 of
electrical conductors.
In one specific embodiments, the communication cable includes three
insulated twisted pairs 12 of electrical conductors each having a
nominal diameter of about 0.034 inches. This includes an electrical
conductor having a nominal diameter of about 0.0201 inches and a
layer 16 of insulation having a thickness of about 0.0065 inches.
For these twisted pairs 12 of electrical conductors the layer 16 of
insulation can be any plenum rated insulation, such as, for
example, FEP. In this embodiment, each of the insulated twisted
pair 18 of electrical conductors has a nominal diameter of about
0,205 inches and a layer 22 of insulating material having a
thickness of about 0.0085 inches.
Preferably, the layer 22 of insulation material of the twisted pair
18 is a modified non-plenum material. For example, such an
insulation material 22 may be a combination of highly brominated
and antimony trioxide filled high density polyethylene (HDPE)
combined with standard HDPE. As another example, the insulation
layer 22 may also be a hydrated mineral filled polyolefin copolymer
blended with HDPE. Although other combinations can be used it is
preferred that the combination is blended at a 50/50 to 75/25 blend
ratio of the flame retarded HDPE to the standard HDPE. Such
combinations improve the flame retardancy and smoke suppression of
the material as well as reduces the fuel load by removing HDPE
while maintaining electrical performance. Two such cables have
successfully passed the Steiner tunnel test.
It has also been found that such a configuration does not
compromise the desired electrical performance of the communication
cable 10 due to the very good electrical and mechanical properties
of the base olefin material. In fact, for the embodiment discussed
above, the standard FEP four pair cable has a weakness in the
typical design in that the twisted pair having the shortest twist
length, i.e., the tightest twist, generally approaches the signal
attenuation failure limit. Usually this is within about 2% of the
passing level. Hence, any process changes must be limited on this
twisted pair to avoid any distortional stresses during manufacture
that would lower the characteristic impedance of the twisted pair
and thus raise the signal attenuation. It has been found that when
this twisted pair is provided with the modified olefin insulation
material the signal attenuation is improved due to the added
ruggedness of olefin material compared to the standard FEP
insulation.
In the preferred embodiment, the communication cable 10 includes a
cable jacket 24 that encases the plurality of twisted pairs 12 and
the at least one twisted pair 18. Preferably, the cable jacket 24
is formed from Ethylene-Trichlorofluoroethylene (E-CTFE). Although
the E-CTFE is preferred, other material, such as, for example,
polyvinylchloride (PVC) or polymer alloys have also passed the
modified Steiner tunnel test and may also be used.
Another communication cable, generally indicated at 26 in FIG. 2
and embodying the principles of the present invention, includes a
first plurality of twisted pairs 28 of electrical conductors having
a first insulating material 30 about each electrical conductor
thereof and a second plurality of twisted pairs 32 of electrical
conductors having a second insulating material 34 about each
electrical conductor thereof. Further, the second plurality of
twisted pairs 32 is no greater than half of the total number of
twisted pairs. For example, in a typically communication cable 26
wherein there is a total of about 25 twisted pairs of electrical
conductors no more than twelve will constitute the second plurality
of twisted pairs 32. The communication cable 26 also includes a
cable jacket 36 that encases the first and second plurality of
twisted pairs, 28 and 34, respectively. The cable jacket 36 is
similar to the cable jacket 24 of the communication cable 10
previously described hereinabove and can be formed of the same
materials.
Although the present invention has been discussed with respect to
one or more specific embodiments it will be understood that other
configurations and arrangements may be used which do not exceed the
spirit and scope hereof. Hence, the present invention is limited
only by the appended claims and the reasonable interpretation
thereof.
* * * * *