Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates generally to devices for
connecting or terminating shielded high voltage power cables
and pertains, more specifically, to connecting devices employed
to facilitate connection to and the termination of metallic
shields in such cables and to enable the utilization of cur-
rently available connectors and terminators with cables of
the type employing metallic shields.
The continued development of underground electrical
power distribution systems, especially in industrial, commer-
cial and residential areas, has led to the evolution of variouspower distribution components, such as shielded electrical
cables, transformers and electrical connectors, capable of service
at higher voltages than previously attainable. Among these com-
ponents, shielded electrical connectors and terminators have
been developed which are readily assembled in the field at the
terminal ends of shielded electrical cables so as to facilitate
the construction and installation of higher voltage underground
power distribution systems.
In installations where the shielded high voltage power
cables are of the type having a central conductor surrounded
by an insulator which, in turn, is surrounded by a shielding
system including a metallic shield, it is often necessary to
make connections to the metallic shield at prescribed locations,
and e~pecially adjacent the terminal ends of the cables where
connectors or terminators are to be installed. It would be
advantageous to have available a connecting device which would
enable an effective connection to such a shielding system to
be accomplished with ease ln systems designed to operate at
the higher voltages now accommodated by the newer power dls-
tribution components of the type described above.
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According to the present invention there is provideda connecting devlce in combination with a high voltage power
cable of the type having an inner conductor, insulation sur-
rounding the conductor, and a shielding system including a
metallic shield with a layer of overlying wire strands thereon
surrounding the insulation~, said connecting device comprising
an electrically conductive bar circu~ferentially around a por-
tion of the shielding system in a manner to establish a radial
gap between the portion of the shielding system and the bar,
the gap being of a size to permit the wire strands to extend
therethrough such that the wire strands are en'abled to be bent
back over an external surface of the bar for electrical connection
thereto; and a plurality of ele'ctrically conductive fingers, all
circumferentially spaced and projecting from the bar in a manner
to allow the fingers to extend axially along the shielding system
when the bar is placed circumferentially thereabout, a first s~.t
of the plurality of fingers being of a first axial length and a
second set of the plurality of fingers being of a second different
axial length, each finger having a portion located remote from the
bar and being attached to the shielding system,'and each space bet-
ween the fingers being of a size to allow different ones of the
wire strands which extend through the gap to pass between adjacent
fingers and be bent back over an external surface of the bar for
electrical connection to the bar.
According to the present invention there is also provided
a method for electricaliy connecting the shielding system of a
high voltage cable with the aid of a connecting device comprising a
circumferentially extending electrically conductive bar having a
plurality of elect'rically conductive fingers, all circumferentially
spaced and projecting therefrom in an axial direction, first ones of
the plurality having a first axially extending length and second ones
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of the fingers having a second different axially extending length,
said method comprising the steps of removing an outer portion of
the cable to expose a region of the shielding system; placing the
bar over the exposed region of the system and bending the bar th'ere-
about such that the bar extends circumferentially around the ex-
posed region in a manner to provide a radial gap between the ex-
posed region and to allow the spaced fingers~ to extend axially a-
long the system: ~assing different ones of a plurality of wire
strands included in the system through the corresponding circum-
ferential spaces between the fingers; connecting the wire strandspassing through the circumferential spaces between the fingers to
the bar; and electrically connecting end portions of the first
fingers to the system at a first axial distance therefrom and ele-
ctrically connecting end portions of the second f'ingers to the
system at a second axial distance from the bar.
According to a stiIl further aspect of the invention there
is provided a connecting device in combination with a shielded high
voltage power cable of the type having an inner conductor, in-
sulation surrounding the conductor, and a shielding system including
a metallic shield surrounding the insulation, said connecting device
comprising a circumferentially extendingelectricallyconductive bar being
placed around a bared portion of the shielding system and having a
longitudinal extent great enough to enable the bar to extend cir-
cumferentially around a major portion of the circumference of the
cable at the bared portion of the shieldin~ system; a plurality of
electrically conductive fingers affixed to the bar, sa.id fingers all
being circumferentially spaced and projecting therefrom in an axial
direction so as to extend axially along the metallic shield when
the bar is so placed circumferentially around the cable; each fin-
ger having an axially extending length and a portion located remotefrom the bar attached to the metallic shield so as to make elec-
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trical contact therewith; and a connecting cond~ctor electrically
connected to and extending from the bar; wherein the shielding
system includes a second metallic shield overlying the first said
metallic shield, the second,metallic shie'ld having a bared portion
terminating short of the first metallic shield at the bared por-
tion thereof; wherein the fingers project from the bar in opposite
axial directions, the fingers including a first set of fingers
extending in one direction and a second set of finger~ extending in
the opposite axial direction such that upon placement of the bar
around the metallic shields, adjacent t~e termination of the second
metallic shield, the first set of fingers extending along the
first metallic shield and connected thereto and the second set of
fingers extending along the second metallic shield and connected there-
to; and wherein each metallic shield is in the form of a spiral metal
sheath having axially adjacent convolutions and the finger portions
are located at different axial distances from the bar for attachment
to selected convolutions of the respective metallic shield.
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The invention will be more fully understood,
while still further objects and advantages will be made
apparent, in the following detailed description of.preferred
embodiments of the invent;on illustrated in the accompanying
drawin~s, in which:
FIG. 1 is a plan view illustrating a completed
installation in which two connecting devices constructed in
accordance with the invention are employed in conjunction with
an electrical connection made between the terminal ends of a
pair of shielded high voltage electrical cables;
FIG. 2 is an enlarged fragmentary plan view
of one end of the installation with portions removed to
reveal details of one of the installed connecting devices;
FIG. 3 is a cross-sectional view taken along
line 3-3 of FIG. 2;
FIG. 4 is a perspective view of a connecting
device of the invention, prior to installation;
FIG. 5 is a plan view of the terminal end of
a high voltage power cable, prepared for the installation of
a connecting device;
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Fig. 6 is a plan view of the terminal end of the cable
with the connecting device in an intermediate stage of
installation;
Fig. 7 is a plan view of the terminal end of a high
voltage power cable of another type, prepared for the installa-
tion of another connecting device constructed in accordance
with the invention;
Fig. 8 is a plan view of the terminal end of the cable
of Fig. 7 with the other connecting device installed thereon;
Fig. 9 is an enlarged cross-sectional view taken along
line 9-9 of Fig. 8; and
Fig. 10 is a plan view of a completed installation
utilizing the connecting device of Figs. 8 and 9.
Referring now to the drawing, and especially to Fig. 1
thereof, there is illustrated a pair of high voltage cables 12
and 14 which are connected together mechanically as well as
electrically by means of a shielded electrical connector 16
and which form a part of an underground power distribution sys-
tem. The cables 12 and 14 are of the type having a central con-
ductor 18 surrounded by insulation 20 which, in turn, is sur-
rounded by a shielding system 22 which, in this instance, in-
cludes a metallic shield in the form of a metallic sheilding
tape 24 and a plurality of wire strands 26 overlying the shield-
ing tape 24 (also see Fig. 5). The shielding system 22 is sur-
~ed by a protective outer ~acket 28 which usually is constructed
of an extruded synthetic resin or an elastomer and, in some in-
stancea, is fabricated of a conductive elastomer.
The connector 16 is of the type having a composite
housing 30 in which a continuous shield is provided by an outer
member of conductive elastomeric material so that a continuous
shield is provided along the connector 16 between the terminated
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shielding systems 22 of the cables 12 and 14. However, it
is not desirable that the shielding systems 22 be connected
solely through the shield provided by the conductive elastomer
of the housing 30. Therefore, it becomes necessary to accom-
modate the current which might appear in the shielding systems
of the cables 12 and 14 in some other manner.
In order to accommodate the current-carrying capacity
of the shielding system 22 of each cable 12 and 14, a con-
necting device 32, constructed in accordance with the invention,
is affixed over a bared portion 34 of the shielding system 22
in each cable 12 and 14. As best seen in Figs. 2, 3 and 4,
the connecting device 32 includes a bar 36 of electrically
conductive material, such as copper or aluminum, in the form
of a loop which enables the bar 36 to be placed over the bared
portion 34 of shielding system 22 and to be bent so as to extend
circumferentially around and conform to the bared portion 34.
The longitudinal extent of bar 36 is great enough to enable
the bar to extend circumferentially around a ma~or portion, that
i8, more than 180, of the circumference of the cable 12 at the
bared portion 34 of the shielding system 22, as seen in Fig. 3.
Bar 36 i8 a relatively conformable metal member which includes
a first portion 38 capable of being conformed into an arcuate
looped configuration and having a flattened cross-sectional
shape and an inner surface 40. Annealed copper and aluminum
are two materials which provide appropriate strength and rigidity
combined with the ability to be conformed, by bending in the
field, to close the looped configuration around a cable. A
plurality of fingers 42 of electrically conductive material,
ordinarily the same material as that of bar 36, are affixed to
the bar 36 and project therefrom in an axial direction so as to
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llZ7qZ8
extend axially along the shielding tape 24 when the bar 36 is
placed circumferentially around the cable, as illustrated in
Figs. 2 and 3. Preferably, fingers 42 are affixed to the inner
surface 40 and secured thereto in good electrical contact, as
well as in effective mechanical connection, as by welding or
brazing. Fingers 42 are spaced circumferentially from one
another and are somewhat flexible relative to the more rigid
structure of the bar 36.
During the installation of connector 16 and the related
connecting devices 32, the bar 36 of each connecting device is
usually placed over the terminal end of a respective cable after
the cable8 are joined together by connector 16. As seen in
Fig, 5, the terminal end of each cable 12 and 14 is prepared by
removing a terminal portion of the outer jacket 28 to expose the
shielding system 22, then cutting the shielding tape 24 to expose
a length of insulation 20. A terminal portion of the insulation
20 is then removed to expose a length of conductor 18. Connector
16 i8 then installed over the exposed length of conductQr 18 of
each cable 12 and 14, and over the corresponding terminal
portions o insulation 20 to connect the terminal ends of cables
12 and 14. The assembly of connector 16 at the terminal ends
of the cables is accomplished in a now well-known manner. A
connecting device 32 with bar 36 in the open looped configura-
tion illustrated in Fig. 4 is then placed over the bared portion
34 of the shielding system 22 and bar 36 is bent to conform the
bar to the cable and tend to close the arcuate portion 38 around
the cable, as illustrated in Fig. 3. The wire strands 26 passing
beneath the bar 36 are trained to pass between the circumferen-
tially spaced fingers 42, as illustrated in phantom in Fig. 6.
Once the bar 36 is in place on the respective cable, the wire
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strands 26 are bent back over the arcuate portion 38 of the
bar, as seen in full lines in Fig. 6, and a clamp 44 is
clamped over the wire strands 26 to secure the wire strands
against the outer jacket 28, as shown in Fig. 2, thereby
holding the bar 36 in place~ The wire strands 26 are then
gathered into a wire bundle 46 which is mechanically secured
and electrically connected to the bar 36 by means of a errule
48 (see Figs. 3 and 4) which is unitary with bar 36 and which
receives the end of wire bundle 46 therein. The ferrule 48 is
lp crimped to secure the wire bundle 46 therein and to assure a
good electrical contact.
Fingers 42, which now extend axially along the shield-
ing tape 24, are attached at portions remote from bar 36 to the
shielding tape so as to make electrical contact therewith. Pre-
ferably, the end portions 50 only of the fingers 42 are affixed
to the shielding tape 24, as by soldering. Since the shielding
tape 24 forms a spiral metal sheath having axially adjacent con-
volutions 52, the lengths of the fingers 42 are varied so that
the soldered connections 54 between the fingers 42 and the
shielding tape 24 are located at different axial distances from
the bar 36 and placed upon selected convolutions 52 of the shield-
ing tape, which selected convolutions may be different adjacent
convolutions. The appropriate choice of the position of each
soldered connection 54 will place the particular soldered
connection 54 within the confines of a convolution 52 so that
the soldered connection 54 will not bridge consecutive convolu-
tions. In this manner, the sheath provided by the shielding tape
24 remains undisturbed and the integrity of the shield is
maintained.
Once the soldered connections 54 are completed, the
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connecting device installation may be sealed by wrapping the
bared portion 34 of the shielding system 22, the bar 36, the
fingers 42 and the clamp 44 with tape 56, as seen in Fig. l,
leaving an integral connecting conductor 60, which is unitary
with bar 36, projecting beyond the tape 56 for further con-
nection, as for example for connection to ground. Tape 56 is
chosen so as to conform closely to the wrapped components not
only for making a good seal against water and other potentially
harmful surrounding elements, but for conducting heat away from
the wrapped components during service.
In order to allow for thermal expansion of the cables
12 and 14 radially beneath each bar 36, during service of the
connecting devices 32, the inner diameter of the inner surface
40 of portion 38 of bar 36 is greater than the outer diameter of
the bared portion 34 of the shielding system 22, thereby estab-
lishing a radial gap 62 between the bar 36 and the cable (see
Fig. 3). The wire strands 26, which pass through the gap 62,
tend to centralize the cable within bar 36 to aid in compensat-
ing for thermal expansion. Since fingers 42 are somewhat
flexible they may be flexed toward the shielding tape 24 for
affixing the portions 50 of the fingers to the shielding tape
and the fingers will flex in response to thermal expansion and
contraction of the cable.
The combination of the weight and integrity of the
bar 36, together with the positive securement and contact of the
fingers 42 with the shielding tape 24 and the connection between
the wire strands 26 and the bar 36 enables the connecting device
to carry amounts of electrical current on par with the current-
carrying ability of the cable shielding system 22. The ability
to maintain the integrity of the electrical connection while com-
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pensating for th~rmal variations, together with the ability
to dissipate excessive heat, adds to the current-handling
capabilities of the connecting device 32. Hence, connecting
devices constructed in accordance with the invention are capable
of satisfactory service at higher voltages than heretofore avail-
able, i.e., above 35 kV, in connecting devices of the type which
are installed easily in the field from component parts manu-
factured in the factory.
Turning now to Figs. 7 through 10, another embodiment
of the invention is illustrated for use in connection with a
high voltage power distribution cable 70 of the type having a
conductor 72 surrounded by insulation 74 which, in turn, is
surrounded by a shielding system 76 which, in this instance,
includes a first shielding tape 78 and a second shielding tape
80 overlying the first shielding tape 78. Again, the shield-
ing system 76 is surrounded by an outer jacket 82.
In preparing the terminal end of cable 70, the shield-
ing tapes 78 and 80 are provided with respective bared portions
84 and 86, the bared portion 86 terminating short of the ter-
mination of the shielding system to establish bared portion 84.
A connecting device constructed in accordance with the invention
is shown at 90 and includes a bar 92 placed adjacent the ter-
mination of second shielding tape 80. Bar 92 is a looped member
of electrically conductive material, such as copper or aluminum,
and has an arcuate configuration with an inner surface 94. The
circumferential extent of bar 92 is great enough to extend around
a major portion of the shielding system of the cable, and the
bar 92 is relatively rigid, but conformable to the required
arcuate configuration.
A plurality of fingers 96 of electrically conductive
_g_
material are affixed to the bar 92 and pro~ect therefrom to
extend axially along the shieldlng system 76. Fingers 96 in-
clude a first set of fingers 100 projecting axially from the
bar 92 in one direction and a second set of fingers 102 pro-
jecting in an axially opposite direction. The fingers 100 of
the first set are affixed to the first shielding tape 78, and
electrically connected thereto, as by soldering portions 104
of fingers 100 which are remote from bar 92, to the shielding
tape 78 at soldered connections 106. The fingers 102 of the
second set are affixed and electrically connected to the
second shielding tape 80 by soldering portions 108 to establish
soldered connections at 110. Where corresponding fingers 100
and 102 are in axial alignment, they may be fabricated in the
form of a unitary finger element affixed to the bar 92 between
the ends of the finger element to provide the axially opposite
fingers 100 and 102. The fingers of each set may be constructed
in various axial lengths for attachment to selected convolutions
of the respective shielding tapes and preferably are spaced cir-
cumferentially from one another around the periphery of the
bar 92.
The inner diameter of the inner surface 94 of bar 92
is greater than the corresponding diameter of the shielding
system 76 so as to provide a radial gap 112 between the bar 92
and the cable 70 for enabling thermal expansion. The relative-
ly flexible fingers 96 are flexed from the bar 92 toward the
shielding system 76 for connection thereto and flex to com-
pensate for thermal conditions during operation.
A flexible connecting conductor 114 is secured and
connected to bar 92, and thereby made integral with the bar, as
by welding, soldering or brazing, and serves to make the
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appropriate electrical connection. To complete the instal-
lation, the components are closely wrapped with tape 116, as
described in connection with the embodiment of Figs. 1 through
6, and connecting conductor 114 passes beyond the ~ape to enable
the appropr~ate electrical connection. As before, an electrical
connector 16 makes the connection between the terminal ends of
cables.
It is to be understood that the above detailed
description of preferred emboiments of the invention are pro-
vided by way of example only. Various details of design andconstruction may be modified without departing from the true
spirit and scope of the invention, as set forth in the appended
claims.
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