Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to overhead power line isolators.
Canadian patent application Serial No. 2,092,741 filed
on March 26, 1993 discloses an isolating switch for an overhead
power line, which isolating switch has a main sub-assembly formed
of two parallel spaced insulators joined at their ends by aluminum
end pieces. The end pieces each have a slot aligned with the
space between the two insulators such that the sub-assembly may be
hung on a hot power line with the line passing along the slots and
the space between the insulators. An integral rod projecting from
each end piece in alignment with but below the slot may then be
clamped to the line by wedges and C-shaped clamps after which the
line may be severed at a location between the end pieces to
isolate the line.
To retain the sub-assembly on the line prior to
attachment of the rods to the line a keeper bar is provided on
each end piece. The keeper bars are pivotally mounted on one side
of the slot and may be swung across the slot when the sub-assembly
is in place on the line to engage respectively two studs on the
other side of the slot. Nuts may then be applied to the studs to
secure the keeper bars in place which in turn retain the sub-
assembly on the line.
Canadian Patent Application Serial No. 2,119,599 filed
on March 22, 1994 discloses an improved mechanism for retaining
the sub-assembly on the power line prior to clamping the end piece
rods to the power line.
It is an object of the present invention to improve even
more on the mounting mechanism of Canadian patent application
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CA 02135263 2003-09-12
50029-10
Serial No. 2,119,599.
Accordingly the present invention provides in a
broad form an isolating switch for an electric power line
comprising a sub-assembly made up of two electrically
conductive end pieces interconnected by at least one
insulator, the end pieces having respective aligned grooves
for registry with the electric power line, and means for
permanently securing the end pieces to the electric power
line, the sub-assembly being provided with means for
mounting the sub-assembly to the power line prior to
permanently securing the end pieces to the power line,
wherein the means for mounting comprises two keeper bars,
each being pivotally mounted on a respective one of the end
pieces and being pivotable manually between a first position
in which the keeper bar is completely clear of the
respective groove and a second position in which the keeper
bar extends across the respective groove to retain the sub-
assembly on the power line, detent means being provided on
each end piece for cooperation with the respective keeper
bar, and spring means urging the keeper bar and detent means
into mutual engagement when the keeper bar is in the second
position to retain the keeper bar in the second postion.
More particularly, in a preferred embodiment the
detent means comprises aligned detent grooves formed on a
pair of raised bosses, one on either side of the groove
which receives the line. When the keeper bar is in the
second position it is received snugly in the aligned detent
grooves and when the keeper bar is in the first position it
is received in only one of the grooves and extends 180° from
the second position.
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Although the invention is particularly applicable to the
power line isolator of Canadian patent application Serial No.
2,092,741, it should be apparent that the invention can also be
used with other types of power line isolators in which a portion
of the isolator is hung on the power line prior to attachment of
the ends of the isolator to the power line.
The invention will now be described in greater detail
with reference to the accompanying drawings, in which:
Figure 1 is a side elevational, partly exploded view of
an isolating switch according to Canadian patent application
Serial No. 2,092,741;
Figure 2 is atop view of the main sub-assembly of the
isolating switch of Figure 1;
Figure 3 is a side elevational view of the isolating
switch of Figures 1 and 2 shown clamped on a power line;
Figure 4 is a top view of the isolating switch shown
clamped on a power line;
Figure 5 is a top view of the main sub-assembly of an
isolating switch incorporating a mounting mechanism according to
the present invention;
Figure 6 is a side view of the main sub-assembly shown
in Figure 5;
Figure 7 is an enlarged view showing details of the
circled portion A of Figure 6;
Figure 8 is an view taken on line 8-8 of Figure 5;
Figure 9 is a schematic view illustrating how the keeper
bar is moved between the open and closed position; and
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Figure 10 is a view similar to Figure 8 but illustrating
a slightly modified embodiment.
Referring firstly to Figures 1 and 2, an isolating
switch 10 comprises a main sub-assembly 11, two C-shaped members
12, two wedges 13 and two jumper studs 14.
The sub-assembly 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 portion 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 at 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
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extending from upper face 30. A nut (not shown) may be used to
engage the stud 32 and secure the keeper bar in the position 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 and 4, these show the
isolating switch 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 sub-
assembly 11 on top of the line 35, then securing the keeper bars
28 and finally rotating the sub-assembly 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 sub-assembly 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 into
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the C-shaped members by means of a powder actuated tool in a
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.
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 switch 10 and power line 35 have been
clamped together the 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, the two cut ends are
forced upwardly and away from each other to isolate the power line
35 or the section between the ends can be cut out completely.
A jumper cable (not shown) may be connected across
jumper studs 14 as described to re-energise the line.
Alternatively, as more completely described in above-mentioned
Canadian patent application Serial No. 2,092,741, the isolating
switch may be formed with a blade switch disposed below and
parallel to the insulator 16 and connected across the end pieces.
Manual operation of the blade switch can be effected selectively
to energise or re-energise the line.
The present invention is particularly concerned with
improving the mechanism for securing the sub-assembly 11 to the
line 35 prior to application of the C-shaped members 12 and
complementary wedges 13. As shown in Figures 1 to 4 the
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previously disclosed mechanism comprises keeper bar 28, pin 29 and
stud 30:
Reference should now be made to Figures 5 through 9 for
an understanding of the improved mounting mechanism of the
invention.
The switch of figs 5 and 6 is similar to that
illustrated in Figures 1 to 4 except as follows. Firstly, a blade
switch 39 is disposed below and parallel to the insulators 16 but
as indicated above, this was disclosed in Canadian patent
application Serial No. 2,092,741 and has no bearing on the present
invention.
Secondly, Figures 1 to 4 illustrate the switch in
prototype form with simplified end pieces 15 formed with
rectangular portions 20 to which the rods 24 are welded while
Figures 5 and 6 illustrate production quality end pieces 15' each
of which is cast as a one piece yoke plate along with rod 24'. In
general, this difference from the earlier design is not considered
inventive but it will be described in greater detail to assist in
an understanding of the switch as a whole and the novel aspect,
namely the mounting mechanism described hereinbelow, in
particular.
In this format of end piece, instead of a through slot
21, the yoke plate 15' is formed with a groove 21' extending
between inner and outer ends 22' and 23' of a generally
rectangular portion 20' and an alignment with a similar groove 20
extending along rod 24'.
Two wing portions 41 are integrally formed with the
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rectangular portion 20' and these terminate in spaced arms 42
which extend parallel to groove 21' but are raised with respect to
the plane of rectangular portion 20' as seen in Figures 6 and 8.
The insulators 16 are securely connected to arms 42 by any
suitable means such as crimping.
Where the wing portions 41 join the rectangular portion
20' two raised generally rectangular bosses 43 and 44 are
integrally formed on the rectangular portion, one on either side
of the groove 21'. These bosses form part of the mechanism for
temporarily mounting the switch sub-assembly 11 on the line 35
according to the invention. More particularly, each boss is
provided on its upper surface with a groove 45 having flat
parallel sides and a flat bottom as shown mast clearly in Figure
7. The grooves 45 of the two bosses are aligned with each other
transversely with respect to the groove 21' which receives the
line 35, and each groove 45 extends the entire width of the boss
43 or 44.
A keeper bar 48 is pivotally mounted to the boss 43 by
means of a bolt 49. More particularly, as shown in Figure 7, an
aperture 50 extends entirely through the thickness of the
rectangular portion 20' and the boss 43, a relatively narrow
portion 51 of aperture 50 opening centrally onto the bottom 52 of
the groove 45 of boss 43 and a relatively wide portion 53 opening
onto the underside 54 of rectangular portion 20'.
The bolt 49 is received in the aperture 50 such that the
head 56 of the bolt is received in the portion 53 of aperture 50
and an upper threaded end 57 of the bolt projects upwardly out of
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the portion 51 of aperture 50 where it is threadably received in a
tapped hole 58 provided in the underside 59 of keeper bar 48
proximate one end of the keeper bar.
The head 56 has a shape and diameter conforming to the
diameter of the wide portion 53 of aperture 50 thereby enabling
sliding movement of the head relative to the aperture. A coil
spring 60 is positioned on the shank of the bolt 49 with one end
in engagement with the head 56 and the other end in engagement
with the shoulder 61 formed between the portions 51 and 53 of
aperture 50. The dimensions of spring 60, aperture 50 and bolt 49
are such that the keeper bar 48 is normally urged by the spring 60
to seat firmly in the groove 45 of boss 43.
The keeper bar 48 has a flat bottom 62 and parallel flat
sides 63 spaced apart slightly less than the width of groove 45
and over most of the bar length there extends a flat top.
However, the bar 48 has a thicker portion 64 proximate one end and
an eye 65 is formed on the thicker portion 64.
Before the sub-assembly 11 is laid on the line 35, the
operator ensures the keeper bar of each yoke plate 15' is in the
dotted position shown in Figure 8. This is the open position
because in this position the keeper bar does not bridge the two
bosses 43 and 44 but extends 180o away from boss 44. If the
keeper bar is in the closed position illustrated by full lines in
Figure 8, the operator simply pulls the keeper bar up and out of
the groove 45 against the action of spring 60 and when the bottom
62 of the keeper bar is clear of the groove 45, the operator
rotates the keeper bar 180° until it aligns once more with the
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groove 45 but this time in the open position where it snaps into
place. This action is illustrated in Figure 9.
The sub-assembly 11 is then raised on to the line 35
using hot sticks engaging the eyes 65. In this way, the sub-
assembly is laid on the line 35 with the bosses 43 and 44
extending downwardly toward the ground. In this position, both
keeper bars 48 can then be rotated 180° to the closed position by
manipulating the hot sticks in a pulling and twisting action as
described above in connection with the opening of the keeper bars.
As each keeper bar rotates it slides over the boss 43
and then snaps into the groove 45 of boss 43 as well as the
aligned groove 45 of boss 44. With the keeper bars 48 now in the
closed position, the sub-assembly 11 can be rotated so that it
hangs below the line 35 by virtue of engagement of the keeper bars
with the line. The strong spring bias and positive engagement
between the keeper bars and the aligned grooves ensures that the
keeper bars remain in the closed position.
Particularly if the switch were not being installed by
hot stick, it would not be necessary to rotate the keeper bars to
the complete 1800 open position. Providing the keeper bars were
rotated sufficiently away from the opposite boss 44 to open up the
line groove 40, the sub-assembly 11 could be applied to the line
and the keeper bars closed as before. Thus, an open position
could be established where the keeper bar has been removed from
its groove 45 and rotated to a 900 position in which it lies along
the upper surface of the boss 43 at right angles to its groove 45.
The spring bias produced by coil spring 60 would be sufficient to
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hold the keeper bar open against the boss 43 until the sub-
assembly 11 had been laid on the line 35 at which time the keeper
bars could then be rotated to the closed position.
In the embodiment shown in Figure 10, the boss 44 does
not have a groove 45. Instead, boss 44 is lowered by an amount
equal to the depth of groove 45. Thus, in the closed position the
keeper bar 48 is received in groove 45 and extends across the
space between the two bosses with its free end in engagement with
the upper surface of boss 44. Although this is not the preferred
embodiment it is believed that the keeper bars of this embodiment
would operate satisfactorily to retain the sub-assembly on the
line 35.
It should be noted that the coil spring 60 is only one
example of a spring which will provide the necessary biasing
action. As another example, a type of spring which is similar to
an undulating washer and is known as a wave spring could be used.
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