Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02092741 2004-03-09
IN-LINE ISOLATOR
Background of the Invention
This invent7~on relates to isolating overhead power
lines.
The most common way to effect such isolation is to
use an assembly which includes two full tension clamps (dead
ends) and an insulator in between them. The first full
tension clamp is fixed to an overhead line allowing the rest
of the assembly to hang freely from the power lir,~e. In some
cases hooks can support the assembly closer to the power
line as to keep the assembly from hanging down and possibly
malting contact with live lines. A mechanical hoist is then
attached to the power line away from the assembly. The
other end of the hoist is then attached to the full tension
clamp at tla.e free end of the assembly. The hoist is then
operated in such a fashion as to take up the assembly
parallel to the power line and introduce some slack line in
between the clamps at each end of the isolator assembly.
The second full tension clamp is now fastened to the power
line. The hoist can now be removed. The power' line tension
is now transferred through the isolator assembly and the
short portion of line in between the two clamps bulges due
to the lack of tension on that portion_ This line portion
can now be cut and separated to isolate the line.
The assembly is now mechanically connected between
cut ends of the line. Often the assembly also includes a
switch connected in parallel across the insulator and both
ends of the switch now have to be connected electrically to
respective portions of the cut line. This may be done using
C-shaped members and wedges.
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This technique is time consuming and difficult for one
man to carry out particularly because of the need for a hoist.
Another technique has been proposed in United States
Patent 4,814,550. This technique involves an isolating
apparatus having clamps pivotally mounted at opposite ends of
an insulator. The clamps can be secured to the power line such
that the insulator lies below and parallel to the line, and
thereafter the power line can be severed between the clamps.
One reason that this apparatus has not found acceptance in
practice is that, after the line is cut, there is an immediate
and sudden straightening of the apparatus caused by the tension
in the line and gives rise to severe forces in the line and
particularly at the clamps.
It is an objeci~ of the invention to provide an
improved isolating apparatus and method.
Summary of the Invention
In its broadesi~ form, the instant invention involves
the use of an offset insulator which can be clamped at opposite
ends to the live power .Line. The one clamping action provides
both a mechanical and electrical connection to the line.
Because the insulator is offset, after the clamping
step the line runs parallel to and spaced from the insulator.
The line may then be cuts between the clamped portions and the
severed ends bent away from each other or the section can be
cut out. There is no whipping of the line after severing
because the offset allows the insulator to be clamped without
displacing the line from its natural lie and because there is
no pivotal connection between the ends of the insulator and the
clamps.
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In a preferred embodiment the isolating apparatus
is formed of two parallel spaced insulators interconnected
by aluminum end pieces which are clamped to the line after
the apparatus is hung on the line with the line passing
along the space between the insulators.
In summary, according to one aspect the invention
provides an isolating apparatus for an electric power line
comprising an elongate insulator having opposite ends, two
electrically conductive end pieces and two electrically
conductive clamps, wherein each end piece is non-pivotably
secured to a respective end of the insulator and includes a
rod, the rods of the end pieces being mutually aligned and
extending parallel to the insulator, each end piece having a
slot and a keeper bar, the slots of the end pieces being
aligned to receive the power line, and the clamps being
arranged to cooperate with the rods to secure the isolating
apparatus to the power line whereby when thus secured the
power line may be cut at a position intermediate the ends of
the insulator.
According to another aspect the invention provides
an isolating apparatus for an electric power line comprising
an elongate insulator having opposite ends, two electrically
conductive clamps and two electrically conductive end pieces
respectively located at the opposite ends of the insulator,
wherein each end piece comprises a rod rigidly secured to a
portion of the end piece which is offset with respect to the
rod, the offset portions of the end pieces being rigidly
secured to the respective opposite ends of the insulator and
the rods being in mutual alignment and cooperating with
respective ones of the clamps to clamp the isolating
apparatus to the power line such that the insulator is
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parallel to but offset from the power line whereby, with the
isolating apparatus secured to the power line, the power
line may be cut at a position intermediate the ends of the
insulator, each end piece having a slot aligned with the
rods for receiving the power line and each end piece having
a keeper bar selectively movable to a position bridging the
slot.
According to another aspect the invention provides
a method of electrically isolating a power line comprising:
securing opposite ends of an isolating apparatus as
described in either of the two preceding paragraphs non-
pivotally to the power line such that the insulator runs
parallel to but offset from the power line; and cutting the
power line between the opposite ends of the insulator.
According to another aspect, the invention
provides a method of electrically isolating a power line
comprising: hanging a power line isolating apparatus on the
power line, the apparatus comprising two elongate
substantially identical insulators, two electrically
conductive end pieces secured to opposite ends of the
insulators and holding the insulators in parallel spaced
relationship, such that the power line runs parallel to and
between the insulators; clamping the end pieces to the power
line; and cutting the power line between the end pieces.
According to a further aspect the invention
provides an isolating apparatus for an electric power line
comprising two elongate substantially identical insulators,
two electrically conductive end pieces and two electrically
conductive clamps, wherein each end piece is non-pivotally
secured to a respective end of both insulators such that the
insulators are parallel and coextensive, each end piece
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including a rod, the rods of the end pieces being mutually
aligned and extending parallel to the insulators, each end
piece having a slot and a keeper bar, the slots of the end
pieces being aligned to receive the power line parallel to
and between the insulators, and the clamps being arranged to
cooperate with the rods to secure the isolating apparatus to
the power line, whereby when thus secured the power line may
be cut at a position intermediate the ends of the
insulators.
According to yet another aspect the invention
provides a method of electrically isolating a power line
comprising: securing opposite ends of an isolating apparatus
as described in the immediately preceding paragraphs non-
pivotally to the power line such that the insulators run
parallel to but offset from the power line; and cutting the
power line between the opposite ends of the insulators.
According to a final aspect the invention provides
an isolating apparatus for an electric power line comprising
two elongate substantially identical insulators; power line
securing means for securing opposite ends of the insulators
to the power line, comprising a pair of end pieces having
the respective ends of said insulators secured thereto in
mutually spaced apart relation such that the insulators are
coextensive and substantially parallel; said power line
securing means each being located between said ends of said
insulators, whereby, in use, with the insulators secured to
the power line the power line is secured in substantially
co-planar parallel relation between the insulators and may
be cut at a position intermediate said end pieces.
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According to a third broad aspect, the invention
provides a method of electrically isolating a power line
comprising: securing opposite ends of an elongate insulator
non-pivotally to the power line such that the insulator runs
parallel to but offset from the power line; and cutting the
power line between the opposite ends of the insulator.
According to a fourth broad aspect the invention
provides an isolating apparatus for an electric power line
comprising two elongate substantially identical insulators and
means for securing opposite ends of the insulators to the power
line such that the insulators are coextensive and substantially
parallel to but offset in opposite directions from the power
line, whereby, with the insulators secured to the power line,
the power line may be cut at a portion intermediate the ends of
the insulators.
According to a fifth broad aspect the invention
provides an isolating apparatus for an electric power line
comprising two elongate substantially identical insulators, two
electrically conductive end pieces secured to opposite ends of
the insulators and holding the insulators in parallel spaced
relationship and means :for clamping the end pieces to the power
line with the power line running parallel to and between the
insulators whereby, with the end pieces clamped to the power
line, the power line may be cut at a portion intermediate the
ends of the insulators.
According to a sixth broad aspect the invention
provides a method of electrically isolating a power line
comprising: hanging a line isolating apparatus on the power
line, the apparatus comprising two elongate substantially
identical insulators, two electrically conductive end pieces
secured to opposite ends of the insulators and holding the
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insulators in parallel spaced relationship, such that the power
line runs parallel to arid between the insulators; clamping the
end pieces to the power line; and cutting the power line
between the end pieces.
Brief Description of the Drawings
Figure 1 is a side elevational, partly exploded view of
an isolating assembly a<:cording to the invention;
Figure 2 is a trop view of the main component of the
isolating assembly of F_Lgure 1;
Figure 3 is a side elevational view of the isolating
assembly shown clamped on a power line;
Figure 4 is a t:op view of the isolating assembly shown
clamped on a power line;'
Figure 5 is an isometric view of the isolating
assembly shown clamped t:o the power line and after the power
line has been cut;
Figure 6 is a view similar to Figure 4 but showing a
modified form of isolat_Lng assembly;
Figure 7 is a ride view of the isolating assembly
shown clamped to the power line and after the power line has
been cut and incorporat=Lng a modified clamping arrangement;
Figure 8 is a fragmentary view showing a further type
of clamping arrangement;'
Figure 9 is a view similar to Figure 3 but showing a
further modified form of isolating assembly; and
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Brief Description of the Drawings
Figure 1 is a side elevational, partly exploded view
of an isolating assembly according to the invention;
Figure 2 is a top view of the main component of the
isolating assembly of Figure 1;
Figure 3 is a side elevational view of the
isolating assembly shown clamped on a power line;
Figure 4 is a top view of the isolating assembly
shown clamped on a power line;
Figure 5 is an isometric view of the isolating
assembly shown clamped to the power line and after the power
line has been cut;
Figure 6 is a view similar to Figure 4 but showing
a modified form of isolating assembly;
Figure 7 is a side view of the isolating assembly
shown clamped to the power line and after the power line has
been cut and incorporating a modified clamping arrangement;
Figure 8 is a fragmentary view showing a further
type of clamping arrangement;
Figure 9 is a view similar to Figure 3 but showing
a further modified form of isolating assembly; and
Figure 10 is a view similar to Figure 3 but showing
an embodiment incorporating a switch.
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Detailed Description of the Preferred Embodiments
Referring firstly to Figures 1 and 2, the isolating
assembly 10 comprises a main component 11, two C-shaped members
12, two wedges 13 and two jumper studs 14.
The main component 11 is formed by 'two aluminum end
pieces 15 spaced apart by two identical parallel spaced Insulators
16 each of which typically is formed of a fibreglass rod 17 having
a rubberized exterior and a series of spaced integral discs 18
which are also rubberized. Porcelain can also be used for the
insulators 16. The insulators 16 are securely connected to the
end pieces 15 by any suitable means such as crimping.
Each end piece 15 has a generally rectangular portion 20
having a through slot 21 extending between an inner end 22 and an
outer end 23 of rectangular portion 20. The two slots 21 are
mutually aligned with an axis extending parallel to and midway
between the rods 17. Each end piece also includes a rod 24 which
is secured to the rectangular gortion 20 for example by means of a
weld and extends from the outer end in alignment with the axis of
the slot 21 as seen in Figure 2 but slightly below the level of
the slot 21 as seen in Figure 1. The rod 24 may have afi its free
end an eye 25 for engagement by a hot stick or hoist.
Each end piece 15 is completed by a keeper bar 28 which
is pivotally mounted on a pin 29 extending from the upper face 30
as seen in Figure 2 of rectangular portion 20. The keeper bar 28
may be swung across the slot such that a notch 31 provided in the
bar at a location remote from pin 29 engages a stud 32 also
extending from upper face 30. A nut (not shown) may be used to
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engage the stud 32 and secure the keeper bar in the gosition shown
in Figure 2.
The two C-shaped members 12 and wedges 13 are also made
of aluminum and are well known per se for interconnecting two
conductors. The C-shaped members 12 each have; two spaced curved
channels 33. The isolating assembly is completed by the two
jumper studs 14 which are formed as angled aluminum or tin plated
copper rods.
Referring now to Figures 3 to 5, these show the
isolating assembly 10 clamped to a power line 35. To apply the
isolating assembly to the power line the main component 11 is hung
on the power line by aligning the power line 35 along the slots 21
and swinging the keeper bars 28 across the respective slots 21 and
securing them to the studs 32 by means of the nuts (not shown .
This step might best be accomplished by firstly laying the main
component 11 on top of the line 35, then securing the keeper bars
28 and finally rotating the main component 11 about line 35 such
that the keeper bars 28 lie on top of the line 35 as shown in
Figures 3 and 4. Other installation practices may be used.
With the main component 11 hung on the power line 35 the
C-shaped members 12 can then be hung over the power line 35 in
registry respectively with the rods 24 of the end pieces 15.
Thus, a curved channel 33 of each C-shaped member 12 encompasses
one of the rods 24 and a portion of power line 35. The jumper
studs 14 are then positioned respectively in the other curved
channels of the C-shaped members and the wedges 13 are forced unto
the C-shaped members by means of a powder actuated tool in a
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manner known per se to clamp the power line 35 securely to the
rods 24 and to clamp the jumper studs 14 to the C-shaped
members.
Figure 5, which is an isometric view looking from
underneath the power 1i e, shows that the rod 24 is preferably
contoured on its upper surface in a fashion complementary to
that of the curved channel 33 so as to define a generally
circular section space for reception of power line 35.
Once the isolating assembly 10 and power line 35 have
been clamped together tine power line can be cut by wire
snippers at a point lying between the two insulators 16,
preferably substantially equidistantly from the end pieces 15.
It is noted that when the power line 35 is cut there is no
recoil of the line or movement of the clamps 12, 13. Then, as
shown in Figure 5 the two cut ends are forced upwardly and away
from each other to isol<~te the power line 35 or the section
between the ends can be cut out completely. A jumper cable 36,
shown in phantom in Figure 5 may be connected across jumper
studs 14 as desired to .re-energise the line.
A jumper cable is only one of several techniques for
re-establishing electrical connection across the cut ends of
the line. Figure 10 shows a particularly preferred arrangement
involving a switch 37 disposed below and parallel to the
insulator 16. The switch includes a blade 38 pivotally
connected at one end 39 to a first pole piece 40 and
selectively engageable at its free end 41 with a second pole
piece 42. Pole piece 40 is interconnected with one of the end
pieces 15 by means of intermediate members 43 and pole piece 42
is interconnected with t:he other end piece 15 by means of
intermediate members 44,.
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Instead of the insulators 16 being displaced
laterally (in the horizontal plane), the isolating assembly
could be rotated 90° so that the insulators are both
located in the vertical plane or the assembly could be
5 rotated to any intermediate position.
Referring now to Figure 6, this shows a form of
the invention in which one of the insulators 16 has been
dispensed with, leaving only a single insulator 16 offset
laterally with respect to the axis of the power line 35.
10 Instead of offsetting the single insulator laterally it may
be offset instead vertically above or below the power line
as illustrated in Figure 9.
With reference to Figure 7, this shows that
instead of clamping means illustrated in Figures 1 to 6 a
bolted clamping mechanism could be used. This again
involves the use of a C-shaped member 12' and a wedge 13'
but these two members are interconnected by a screw 46 which
can be turned to force the wedge into the C-shaped member
thereby clamping the power line 35 to the rod 24 of the
isolating assembly. Figure 7 also shows the optional use of
stirrups 47 instead of angled jumper studs 14.
Finally, Figure 8 shows yet another type of
clamping mechanism known per se, a so-called wave clamp
which involves the use of a member 48 secured opposite the
rod 24 by means of U-shaped bolts 49 and nuts 50.
Tightening of the nuts 50 clamps power line 35 between
member 48 and rod 24.
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It is envisaged that with appropriate minor
refinements the apparatus could be installed using a hot
stick but in its present form it is more appropriately
applied directly.
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