HIGH PERFORMANCE DATA CABLE AND A UL 910 PLENUM
NON-FLUORINATED JACKET HIGH PERFORMANCE DATA CABLE
FIELD OF THE INVENTION
This invention relates to high performance data cables that successfully
enables transmission in the frequency range of 0.3 MHz to 1200 MHz and
especially in the range of 1.0 to 600 MHz and/or 1.0 to 1000 MHz . Also to UL
910 high-performance plenum cables that have a non-fluorinated jacket. More
particularly, the invention relates to high-performance data cable which are
bound- lateral shielded twisted pair cables. Also, this relates more particularly to
the at least category 5 plenum UL 910 cables having a non-fluorinated jacket
and a heat-resistant flame-retardant tape on the inner circumference of the
jacket.
BACKGROUND OF THE INVENTION
The current high performance data cables usually utilize as a shield a
heavy, stiff, 2 mil aluminum tape with a 1 mil polyester (Mylar ) backing. The
shield is wrapped around each unshielded twisted pair subgroup within an
application lay length that is equal to the length of the cables overall cable lay,
typically lays of 4.0 to 6.0 inches. The tape is about 0.5 inches wide. The
application angle of the wrapping is shallow, based on the long overall cable lay
(5 inches) and the tape is almost parallel with the twisted pair laterally axis. A
typical cable has 4 pairs of twisted pair cables with a 40 to 65% tinned copper
braid applied over the four pairs and a final thermoplastic jacket extruded over
the braided pairs to complete the cable. The shallow application angle of the
metal shield tape generally creates the problem of allowing the tape to open up
during the cabling operation before a binder or spirally applied drain wire can
capture it.
Also, the tape doesn't generally follow the pairs contour under the tape.
Tape gaps are created with this process around the unshielded twisted pair core
that do not provide a sufficiently stable ground plane to meet the industry
standard electrical requirements such as CENELEC pr EN 50288 -4 -1.
The known cable structure noted above is mechanically unsound in a
static state, and the electricals are unstable under installation conditions since
the single overall braid cannot adequately insure the tape lap doesn't "flower"
open when the cable is flexed. This "flowering" increases NEXT, and further
erodes impedance/RL performance as the ground plane is upset. This adds to
attenuation non-uniformity. The impedance numbers are even worse under
flexing since the conductor's center to center, as well as the ground plane,
changes. The higher the bandwidth requirement, the worse these issues become.
We know of no cable structure for high performance UL 910 plenum
data cables that have a non-fluorinated jacket. A plenum cable that used a
fluorinated jacket and a temperature-resistant flame-retardant separator tape
such as Nomex® (a temperature-resistant flame-retardant nylon manufactured
by DuPont) was used and sold by Belden Wire & Cable Company more than a
year prior to this invention. The Nomex® tape in those cables kept the
fluorinated (FEP) jacket from dripping and producing high peak smoke numbers
in the UL 910 burn test.
SUMMARY OF THE INVENTION
Our invention uses on each twisted pair cable a lateral wrapped shielding
tape that is bound with a fabric or metal binder to meet impedance/RL,
attenuation uniformity, and capacitance unbalance that is required.
Our invention eliminates most of the trapped air that is normally found
in shielded twisted pair cables. This is done by utilizing a lateral wrapped
shield with preferably a minimum 10% overlap and which has a 0.33 to 2.0 mil
and preferably a 1 mil metal layer. The lateral wrapped shield is held together by
an appropriate binder and preferably by a textile or metal braid or textile
helically wrapped thread to provide good shielding with improved impedance
control. When desired, a short fold can be applied along the lateral seam of the
shield for improved EMI/Rfi isolation. The consistent ground plane created
along the cables length allows better capacitance unbalance as well as improved
attenuation uniformity through the reduction of RL reflections and capacitance
unbalance.
Our invention also provides for substantial geometric stability under
flexing. The use of a tight lateral shield with at least a 10 % overlap and a textile
or metal binder, eliminates tape gaps and flowering under flexing. This
establishes a very stable level of physical and electrical performance under
adverse use conditions. Our twisted pair cable center to center distances
indicated as (d) in Fig. 3, and conductor to ground distances, remain much
more stable than those of the previous cables.
Our cables are especially beneficial for use as category 7 and higher
performance cables. This is especially true for those cables that we laterally
shield and bind and are used out to 600 MHz or 1000 MHz. The typical high-
performance data cable when made according to our invention, has four (4)
twisted pair cables with each twisted pair cable made up of two foam or non-
foam insulated (fluorocopolymer or polyolefin) singles. Each of the twisted pair
cables has the unique tight lateral metal shield tape wrapped around it with the
tape and its lateral short fold seam tightly held in place with a tight binder such
as a fabric or metal braid or a helical thread. When a braid is used as the
binder, it is a 40 to 95% braid. When a thread is used, it is preferably helically
wound. The bound-lateral shielded pairs are S-Z'd or planetary together into a
bunched or bundled configuration. The bundled pairs may be bundled by an
overall 40 to 95%o braid or thread. A final thermoplastic jacket (fluorocopolymer
or a polyolefin or polyvinyl chloride) is extruded over the bundled twisted pair
cables.
Generally the metal shield is an aluminum tape or a composite tape such
as a short fold BELDFOIL tape (this is a shield in which metal foil or coating is
applied to one side of a supporting plastic film), or a DUOFOIL tape ( this is a
shield in which the metallic foil or coating is applied to both sides of a
supporting plastic film) or a free edge BELDFOIL tape. The overall metal
thickness is 0.33 to 2.0 mil aluminum layer thickness and preferably about a 1.0
mil. Although aluminum is referred to, any suitable metal normally used for
such metal and composite metal tapes can be used such as copper, copper alloy,
silver, nickel, etc. Each twisted pair is wrapped with the metal facing outwardly
and although the most preferred wrap is about a 25% overlap, the overlap may vary as a practical matter from 10 to 50%. The preferred shield that gives the
best attenuation and impedance characteristics are those tapes that are joined to
provide a shorting effect. However, with a suitable overlap, the short fold can be
eliminated.
The number of shielded twisted pairs in a high performance data cable is
generally from 4 to 8 but may be more if desired. The tension of the laterally
wrapped shield and the binder are such that the wrapped shield and binder
eliminate most of the air to provide a standard impedance deviation for the
bound-laterally shielded twisted pair cable and an average standard impedance
deviation for the high performance data cable which has a plurality of laterally
shielded twisted pairs. The tension on the shielding tape and binder are such
that there is only a 25% or less and preferably 18 % or less void space of the
entire cross-sectional area of the laterally shielded twisted pair taken along any
point in the length of the cable.
We provide a high performance twisted pair data cable having a shield
laterally wrapped around an unshielded twisted pair cable and a fabric or metal
braid or yarn simultaneously or subsequently wrapped around the lateral shield
to bind the shield. The wrapping of the shield and binder(the braid or thread) is
at a tension such that for an individual twisted pair that may be used on its own,
the individual pair has an unfitted impedance that has a nominal or standard
impedance deviation for each bound-laterally shielded twisted pair cable that is rated for up to 600 MHz a standard impedance deviation of 3.5 or less from 1.0
to 600 MHz and with no single impedance deviation being greater than 6.0, and
for a cable rated for up to 1000 MHz a standard impedance deviation 4.5 or less
from 1.0-1000 MHz and with no single impedance deviation being greater than
6.0. The high-performance data cable which has a plurality of bound-laterally
shielded twisted pair cables and is rated at up to 600 MHz has an average
standard impedance deviation for all of the plurality of bound-shielded twisted
pairs of 3.5 or less from 1.0 to 600 MHz and with no single standard deviation
for any of the cables being greater than 6.0. The high-performance data cable
which has a plurality of bound-laterally shielded twisted pair cables and is rated
at up to 1000 MHz has an average standard impedance deviation for all of the
plurality of bound-laterally shielded twisted pairs of and 4.5 or less from 1.0-
1000 MHz and with no single standard deviation for any of the cables being
greater than 6.O.. The standard impedance deviation is calculated around a mean
or average impedance of 50 to 200 ohms and with at least 350 frequency
measurement taken on a 328 ft. or longer cable.
Also, we provide a high performance data cable that has the ability to be
labeled as a UL910 high performance data plenum cable. This cable preferably
has a non-fluorinated jacket and a temperature-resistant flame-retardant
separator tape beneath and in contact with the jacket.
Other advantages of the invention will become more apparent upon
reading the following preferred description taken in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a twisted pair cable used in the present invention.
Fig. 2 is a perspective view of a lateral shielded twisted pair cable according to
the present invention.
Fig. 3 is an enlarged cross-section taken along lines 3-3 of Fig. 2.
Fig. 4A is an enlarged cross-section of a braided lateral shielded twisted pair
cable according to the present invention.
Fig. 4B is an enlarged cross-section of a thread bound lateral shielded twisted
pair cable according to the present invention.
Fig. 5 is a cross-section of a cable containing four of the cables of Fig. 4A.
Fig. 6 is a perspective view of the cable of Fig. 5.
Fig. 7 is a perspective view of a cable containing four of the cables of Fig. 4B.
Fig. 8 is a perspective view of one of our plenum UL910 high performance data
cables.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates a twisted pair cable 10 having a pair of conductors 12
and 13 which are preferably solid copper conductors but can be any conductor
that is suitable for high performance data cables. Each of the conductors 12 and
13 have extruded thereon an appropriate insulation 14 and 15 which may be
foamed or non-foamed fluorocopolymer or an appropriate polyolefin.
Figure 2 illustrates the twisted pair of Figure 1, tightly wrapped with a
metal shield 16. The metal shield can be any appropriate shield such as a metal
tape or a composite tape with a non-metal base such as a polyester (i.e.
MYLAR) having on one or both sides of the non-metal base a metal normally
used in cable shields. The metal for the tape and the composite tape being
aluminum, copper, copper alloy, nickel, silver, etc. The thickness of the overall
metal is 0.33 to 2.0 mil and preferably 1.0 mil. The shield is a metal shield such
as, the short fold BELDFOIL type tapes, or the DUOFOIL type tapes which is a
tape where metal is on both sides of the tape.
The tape 16 is laterally wrapped with sufficient pressure as shown in
Figure 3 so as not to crush the insulation 14 and 15 but to provide a small void
space 17 that is less than 25% of the cross-sectional area shown in Figure 3.
Preferably the void space is less than 18% of the cross-sectional area shown in
Figure 3. The tightly wrapped tape 16 conforms to the outer shape of the
twisted pair 10 to provide the laterally shielded twisted pair cable 10A. The
tape 16 is wrapped with a slight overlap and with an optional short fold. As
noted above, the preferred thickness of the aluminum or metal is 1 mil. The
width of the tape is sufficient to provide a 10% minimum overlap.
As shown in Figures 4A and 4B, the shielded twisted pair cable
10A(Fig. 3) is tightly held together by a binder 18 or 18' to provide the bound-
shielded cables 10B and IOC. The tension on the tape and binder wrap is
sufficiently tight to conform to the contours of the unshielded twisted pair 10 to
provide a substantially oval cross-section configuration but is not so tight that it
will deform the insulation 14 and 15. The lateral wrapping and binding are done
at such a tension that it eliminates substantially most of the air within the bound
shielded twisted pair cables 10B and IOC. This provides at any point in the length of the cable, a tight oval cross-section with voids 17. This tight wrapping
provides the standard impedance deviation and the average standard impedance
deviation noted above.
The insulation is preferably a foamed fluorocopolymer having a
thickness of 0.010 - 0.060 inches and preferably 0.015 to 0.020 inches. The
individual conductors 12 and 13 are generally 20 to 30 AWG and preferably 22
to 24 AWG.
The conductors can be solid or stranded and are preferably solid. The
lay length for all of the four twisted pair cables 10 may be the same or different
and right and/or left hand. The lay is preferably 0.3-2.0 inches. The overall
cable lay is generally 10 to 20 times the cable's average core diameter.
The binder 18 is either a fabric (i.e., Aramid) or metal braid which is
preferably a 40-95%) braid. The metal is preferably a 45-65% tinned copper
braid but can be any type metal braid that would be appropriate for a high
performance cable such as category 7 data cable, i.e. copper, copper alloy,
bronze (a copper alloy which alloying element is other than nickel or zinc),
silver, etc.
The binder 18' is a fabric thread (Aramide ) that is helically wrapped to
provide a 40-95%) binding. We preferably use an Aramid 760 denier thread
having a 1/4 inch helical lay.
Referring to Figure 5, the bound shielded cable 10B or 10C has a jacket
19 extruded thereover to produce the high performance data cable 20 of the
present invention. The jacket can be any suitable cable jacket material that would be suitable for a category 7 cable - a thermoplastic such as flame
retardant polyethylene, polyvinyl chloride, fluorocopolymers, etc.
Fig. 6 illustrates a cable 20 having therein four braided-shielded twisted
pair cables 10B. An optional ground wire 21 is between the cables 10B. The
ground wire of course can be located in any suitable location such as just under
the jacket and /or used to bundle the four braided-shielded cables 10B.
Fig. 7 illustrates a cable 25 having therein the four thread bound-
shielded twisted pair cables IOC. The four thread bound-shielded twisted pair
cables IOC are further wrapped or bundled with a metal or fabric braid 22. The
braid 22 is generally the same type as that set forth above for braid 18. An
optional ground wire 21 is between the cables IOC. As above, the ground wire
of course can be located in any suitable location such as just under the jacket
and /or used to bundle the four thread bound-shielded cables IOC.
Fig. 8 illustrates a cable 30 having a jacket 26, a helically or laterally
wrapped separator tape 27 below the jacket. The separator tape 27 surrounds
the four twisted pair thread bound-shielded cables 10C and their binding braid
22. The jacket 26 is a non-fluorinated jacket such as polyvinyl chloride. The
separator tape 27 is a temperature-resistant flame retardant separator tape such
as Nomex®. The construction of this cable is similar to the cable of Figure 7
except this cable has the separator tape 27 and does not have a fluorinated
jacket. When desired, the plurality of these non-metal braided or serve shielded
twisted pair cables can be bundled or wrapped by the ground wire 21. The
bundled twisted pair cables then have the separator tape placed thereover and
the jacket 26 extruded thereover.
As its shown in our following examples 1-7. the high performance
braided lateral shielded twisted pair cables have an unfitted impedance that has a standard impedance deviation for cables rated up to 600 MHz, of 3.5 or less
when taking at least 350 measurements of from 1.0 to 600 MHz and for cables
rated up to 1000 MHz, of 4.5 or less when taking at least 350 measurements
from 1.0-1000 MHz. The high-performance data cables which have a plurality
of the braided-shielded twisted pair cables has an average standard impedance
deviation for all of the plurality of braided-shielded twisted pairs of 3.5 or less
from 1.0 to 600 MHz and 4.5 or less from 1.0-1000 MHz and no single standard
impedance deviation is greater than 6.0. The test for all of the Examples was
the impedance tests as required by CENELEC and were conducted on 328 ft.
lengths of bound-shielded twisted pair cables wherein the shield was laterally
wrapped to provide the twisted pair cables 10A . The lateral shield was a
BELDFOIL tape having a 1 mil aluminum thickness. The tape was laterally
wrapped with a slight overlap. The lateral tape was bound with a metal braid.
Measurements started at 0.3 MHz and at least three hundred and fifty (350)
measurements were taken from about 1 to 600 MHz for Examples 1 and 8 and
from about 1.0 to 1000 MHz for Examples 2-7. The cable conductors 12 and 13
were 22 AWG solid copper and the insulations 14 and 15 were FEP. The
measurements were taken at various temperatures and adjusted to 20°C. All of
the cables have a void 17 of less than 18% and the test were taken around the
mean impedance close to 100 ohms.
EXAMPLE 1
A 328 ft. length of the above braided-shielded twisted pair cable 10B
was tested at 23.3 °C. The cable impedance was measured over 0.3 to 600 MHz
and at least 350 measurements were taken between 1.0 and 600 MHz. The
braided-shielded twisted pair cable was tested and had a standard impedance
deviation of 1.7714 taken around a mean impedance of 95.2619.
EXAMPLE 2
A 328 ft. length of the above braided-shielded twisted pair cable 10B
was tested at 23.3 °C. The cable impedance was measured over 0.3 to 1000
MHz and at least 350 measurements were taken between 1.0 and 1000 MHz.
The braided-shielded twisted pair cable was tested and had a standard
impedance deviation of 2.8565 taken around a mean impedance of 94.3178.
EXAMPLE 3
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 23.9°C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 1000 MHz. At least 350 measurements were taken
between 1.0 and 1000 MHz. The following data was adjusted to 20°C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 4.2744 taken around a mean impedance of 100.5321.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 5.1630 taken around a mean impedance of 101.4416.
The third braided-shielded twisted pair cable had a standard impedance deviation of 4.0469 taken around a mean impedance of 101.4583.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 4.3360 taken around a mean impedance of 100.7506.
The high-performance cable 20 of this example had an average standard
impedance deviation of 4.4551( (4.2744+5.1630+4.0469+4.3360) / 4 ).
EXAMPLE 4
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 23.9 °C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 1000 MHz. At least 350 measurements were taken
between 1.0 and 1000 MHz. The following data was adjusted to 20°C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 4.0430 taken around a mean impedance of 101.1783.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 4.0027 taken around a mean impedance of 101.3086.
The third braided-shielded twisted pair cable had a standard impedance
deviation of 3.6038 taken around a mean impedance of 101.7716.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 4.0092 taken around a mean impedance of 101.3598.
The high-performance cable 20 of this example had an average standard
impedance deviation of 3.9147 ( ( 4.0430+ 4.0027+ 3.6038+ 4.0092) / 4 ).
EXAMPLE 5
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 23.9°C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 1000 MHz. At least 350 measurements were taken
between 1.0 and 1000 MHz. The following data was adjusted to 20 °C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 3.2469 taken around a mean impedance of 199.2035.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 4.2070 taken around a mean impedance of 100.9596.
The third braided-shielded twisted pair cable had a standard impedance
deviation of 3.4690 taken around a mean impedance of 102.8214.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 3.8990 taken around a mean impedance of 101.2338.
The high-performance cable 20 of this example had an average standard
impedance deviation of 3.7055 ( (3.2469+ 4.2070+ 3.4690+ 3.8990) / 4 ).
EXAMPLE 6
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 24.2 °C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 1000 MHz. At least 350 measurements were taken
between 1.0 and 1000 MHz. The following data was adjusted to 20°C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 4.0488 taken around a mean impedance of 101.4423.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 4.2081 taken around a mean impedance of 100.9498.
The third braided-shielded twisted pair cable had a standard impedance
deviation of 4.5567 taken around a mean impedance of 102.0121.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 3.6408 taken around a mean impedance of 102.9531.
The high-performance cable 20 of this example had an average standard
impedance deviation of 4.1136 ( ( 4.0488+ 4.2081+ 4.5567+ 3.6408) / 4 ).
EXAMPLE 7
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 24.2 °C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 1000 MHz. At least 350 measurements were taken
between 1.0 and 1000 MHz. The following data was adjusted to 20 °C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 3.6939 taken around a mean impedance of 102.0776.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 3.8658 taken around a mean impedance of 100.4614.
The third braided-shielded twisted pair cable had a standard impedance
deviation of 3.5208 taken around a mean impedance of 99.7808.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 3.9835 taken around a mean impedance of 100.0594.
The high-performance cable 20 of this example had an average standard
impedance deviation of 3.7660 ( (3.6939+ 3.8658+ 3.5208+ 3.9835) / 4 ) .
EXAMPLE 8
A 328 ft. length of the above high-performance data cable 20 having
four braided-shielded twisted pair cables 10B was tested at 24.4 °C. The
impedance for each of the four braided-shielded twisted pair cables was
measured over 0.3 to 600 MHz. At least 350 measurements were taken between
1.0 and 600 MHz. The following data was adjusted to 20 °C.
The first braided-shielded twisted pair cable had a standard impedance
deviation of 3.5621 taken around a mean impedance of 102.2971.
The second braided-shielded twisted pair cable had a standard
impedance deviation of 3.9185 taken around a mean impedance of 103.9484.
The third braided-shielded twisted pair cable had a standard impedance
deviation of 2.6943 taken around a mean impedance of 103.2519.
The fourth braided-shielded twisted pair cable had a standard impedance
deviation of 2.5206 taken around a mean impedance of 102.9625.
The high-performance cable 20 of this example had an average standard
impedance deviation of 3.1739 ( (3.5621+ 3.9185+ 2.6943+ 2.5206) / 4 ) .
EXAMPLE 9
Two cables of Figure 8 were UL 910 tested. Each cable had four twisted
pair thread bound-shielded cables IOC. Each of the cables shields 16 was a 2
mils aluminum/0.5 mills polyester tape having a 0.625 inch width. Each of the
shields 16 were bound with an Aramid 760 thread. The four thread bound-
shielded cables were wrapped with a 40 % tinned copper braid. The four braid bundled cables were wrapped with a 2 mils Nomex separator tape having a
1.250 inch width. Over the separated tape was an extruded polyvinyl chloride
jacket. Both cables passed the UL 910 plenum test. During the UL 910 plenum
test, the first cable registered a flame of 1.5 ft., a 0.32 Peak and a 0.09 Avg P/F.
The second cable registered a flame of 1.5 ft., a 0.29 Peak and a 0.09 Avg P/F.
Both cables would be rated as category 7 cables with a rating of up to
1000MHz.
Although our invention for the UL 910 plenum at least category 5 high-
performance data cable was UL 910 tested on the cable of figure 8 which is a
category 7 cable, it is understood that our invention is to be considered as not
being limited to this specific construction of the cable but is directed to any
category 5 or higher cable utilizing a non-fluorinated jacket such as a polyvinyl
chloride jacket and between the jacket and cable core there is a temperature-
resistant flame-retardant separator tape. For instance, we provide a UL 910
plenum high-performance data cable having a rating of up to 600MHz that has
the structure disclosed in our co-pending application, which are tightly wrapped
helical shielded twisted pair cables, and utilizing in that cable a non-fluorinated
jacket such as a polyvinyl chloride jacket and between the jacket and cable core,
a temperature-resistant flame-retardant separator tape. Our UL 910 plenum at
least category 5 high-performance data cable is not limited to the cables just
mentioned above but is for UL 910 plenum at least category 5 high-performance
data cable that has a non-fluorinated jacket and between the jacket and cable
core, a temperature-resistant flame-retardant separator tape.
It will, of course, be appreciated that the embodiments which have just
been described have been given by way of illustration, and the invention is not
limited to the precise embodiments described herein. Various changes and
modifications may be effected by one skilled in the art at without departing from
the scope or spirit of the invention as defined in the appended claims.