Electrical cutout having a linkbreak lever

An electrical cutout is disclosed for electrical connection between a line terminal and a load terminal. The cutout includes an insulator having a first and a second end. A first electrical conductor is rigidly secured to the first end of the insulator, the first conductor being electrically connected to the line terminal. A second electrical conductor is rigidly secured to the second end of the insulator, the second conductor being electrically connected to the load terminal. A fuse tube extends between the first and the second conductors and a fuse link extends through the fuse tube and includes a first and a second end. The second end or pigtail of the fuse link is electrically connected to the second electrical conductor. A cap is disposed adjacent the first end of the fuse link, the cap being electrically connected to the first end of the fuse link such that the cap frictionally cooperates with the first conductor. A linkbreak lever for breaking the fuse link is pivotally connected to the second conductor such that when the linkbreak lever is pivoted away from the fuse link in a plane extending through the ends of the insulator and the fuse tube, the moment created by the force required to break the fuse link is opposite in direction and less than the moment resulting from the retentional force between the first conductor and the cap.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an electrical cutout which is electrically 
connected in series between a line terminal and a load terminal. More 
specifically, this invention relates to an electrical cutout which 
includes a linkbreak lever for breaking the fuse link and interrupting the 
load current prior to disengaging the fuse tube or the like. 
2. Information Disclosure Statement 
In order to protect transformer equipment and the like in a power supply 
circuit, it is customary to install an electrical cutout device between 
the transformer line and the load. These electrical cutouts include a 
fusible link and removable fuseholder which cooperate automatically with 
each other to which break the circuit in the event of an electrical 
overload. Furthermore, such electrical cutouts enable a lineman to 
manually break the circuit between the transformer and the load. 
A typical electrical cutout includes an elongated insulator of porcelain or 
other ceramic material. The insulator includes an insulator support 
disposed midway between the ends of the insulator. Usually, the insulator 
support is embedded within the insulator using an organic or inorganic 
cement for bonding the insulator support within the insulator. However, 
the insulator support may be secured to the mid portion of the insulator 
by means of metal bands or the like. The insulator support is anchored to 
a line pole or the like and a first and a second electrical conductor are 
rigidly secured to the first and second ends respectively of the 
insulator. The line wire from the transformer is connected to the line 
terminal of the first conductor and the load wire is connected to the load 
terminal of the second conductor. A removable fuse tube extends between 
the first and the second conductors and a fuse link having a first and a 
second end thereof extends through the fuse tube. A fusible head portion 
of the fuse link is secured between a first end of the fuse tube and a 
screw fitting cap which cooperates with the first end of the fuse tube. 
The second end or pigtail of the fuse link extends from the second or 
lower end of the fuse tube and is anchored in electrical contact with the 
second electrical conductor. The lower or second end of the fuse tube is 
pivotally connected to the lower or second conductor and the linesman by 
means of an insulating line pole pivots the first end of the fuse tube 
upwardly until the cap abuts against the first conductor and forms an 
electrical connection therewith. In the prior art, such electrical cutouts 
usually incorporate a positive latching mechanism for latching the cap 
into engagement with the upper or first conductor. Various proposals have 
been disclosed which include linkbreak levers of various configurations 
for breaking the fuse link prior to releasing the positive latching 
mechanism. In use of the prior art cutouts when an overload occurs the 
fuse link melts thereby breaking the electrical circuit. The fuse tubes 
are usually fabricated from materials which on exposure to the high 
temperatures generated during the melting of the fuse link generate arc 
extinguishing gases which escape from the interior of the fuse tube 
through the lower end thereof. However, when the cutout is on load and for 
some reason it becomes necessary to disconnect the electrical load from 
the supply, it will be evident to those skilled in the art that if the cap 
is moved out of engagement with the upper conductor in order to break the 
electrical circuit, arcing will occur between the upper conductor and the 
cap which may result in damage to the upper conductor necessitating 
replacement of the entire cutout. In addition, this arc creates a safety 
concern for the lineman who is manually disconnecting the load from the 
supply. 
In order to overcome these problems, as stated hereinbefore, various 
linkbreak devices have been disclosed for breaking the fuse link within 
the fuse tube prior to removal of the cap from engagement with the upper 
conductor. In the prior art, various linkbreak levers have been proposed 
in which the lever extends in the plane of the insulator and fuse tube 
such that downward movement of the lever by the lineman using an 
insulating line pole results in breaking of the fuse link by means of the 
increased tension applied to the pigtail along the length of the fuse 
link. Due to the moment imparted to the fuse tube by such downward 
pivoting of the linkbreak lever, such prior art cutouts have necessitated 
the use of a positive latching mechanism as stated hereinbefore for 
positively latching the cap into engagement with the upper conductor. Such 
positive latching mechanisms have involved increased overall costs in the 
production of such cutouts and there has existed in the art a need of a 
cutout in which the frictional force between the cap and upper conductor 
is sufficient to hold the fuse tube in position until the fuse link is 
broken. 
However, with conventional caps, the portion of the cap which cooperates 
with a detent in the upper conductor is of semispherical configuration for 
cooperating with the spherical detent in the upper contact. The 
semispherical configuration of the cap does not provide sufficient 
frictional resistance to prevent movement of the cap away from the detent 
during pivotal movement of the linkbreak lever away from the fuse tube in 
a plane extending through the end of the insulator and the fuse tube. 
In an attempt to overcome the aforementioned problem, various proposals 
have been disclosed wherein the handle of the linkbreak lever extends in 
the aforementioned plane but is pivoted upwardly towards the fuse tube in 
order to avoid the disengagement of the cap from the detent. However, this 
disposition of the linkbreak handle is relatively difficult to operate. 
Furthermore, a linkbreak lever has been proposed in which the handle of the 
lever extends laterally relative to the aforementioned plane and this 
proposal while permitting the utilization of a conventional detent 
arrangement has proved relatively difficult to operate with a line pole 
because of the lateral disposition of the handle and the increasing cost 
of manufacture. 
U.S. Pat. No. 2,514,163 to Pitman discloses a linkbreak handle which is 
pushed upwardly by the lineman's line pole to break the fuse link. The 
upward force on the handle urges the cap against the detent of the upper 
conductor. 
U.S. Pat. No. 2,630,508 to Meisenheimer, et al. teaches a linkbreak lever 
handle which extends from the pivotal point 38 in a direction from the 
fuse tube towards the insulator, thereby disposing the handle 39 in an 
inaccessible location. 
The present invention seeks to overcome the aforementioned inadequacies of 
the prior art devices by the provision of a cap having a frustoconical 
configuration which increases the frictional force between the cap and the 
detent to prevent disengagement of the cap during a linkbreak operation. 
Therefore, it is a primary object of this invention to provide an 
electrical cutout that overcomes the inadequacies of the prior art devices 
and provided an improvement which significantly contributes to the low 
cost of manufacture of a cutout. 
Another object of the present invention is the provision of an electrical 
cutout in which downward movement on the handle of the linkbreak lever 
away from the fuse tube in a direction from the insulator towards the fuse 
tube results in breaking of the fuse link before disengagement of the cap 
relative to the detent. 
Another object of the present invention is the provision of an electrical 
cutout having a cantilever contact which defines a detent, the detent 
cooperating with a cap of frustoconical configuration which provides 
improved retentional engagement between the cap and the detent. 
Another object of the present invention is the provision of an electrical 
cutout which avoids the necessity of providing a positive latch between 
the cap and the upper contact. 
Another object of the present invention is the provision of an electrical 
cutout in which the linkbreak lever extends away from the fuse tube in a 
direction from the insulator towards the fuse tube. 
The foregoing has outlined some of the more pertinent objects of the 
present invention. These objects should be construed to be merely 
illustrative of some of the more prominent features and applications of 
the invention. Many other beneficial results can be obtained by applying 
the disclosed invention in a different manner or modifying the invention 
within the scope of the invention. Particularly with regard to the use of 
the invention disclosed herein, this should not be construed as being 
limited to electrical cutouts having a single insulator but should include 
cutouts in which the upper and the lower conductors are respectively 
supported by individual insulators or the like. 
SUMMARY OF THE INVENTION 
The electrical cutout of the present invention is defined by the appended 
claims with a specific embodiment shown in the attached drawings. For the 
purpose of summarizing the invention, the invention relates to an 
electrical cutout which is electrically connected in series between a line 
terminal and a load terminal. The electrical cutout comprises an insulator 
having a first and a second end. A first electrical conductor is rigidly 
secured to the first end of the insulator with the first conductor being 
electrically connected to the line terminal. A second electrical conductor 
is rigidly secured to the second end of the insulator with the second 
conductor being electrically connected to the load terminal. A fuse tube 
extends between the first and the second conductors and a fuse link 
extends through the fuse tube. The fuse link includes a first and a second 
end thereof and the second end of the fuse link is electrically connected 
to the second conductor. Cap means are disposed adjacent the first end of 
the fuse link, the cap means being electrically connected to the first end 
of the fuse link with the cap means frictionally cooperating with the 
first conductor. A link break means for breaking the fuse link is 
pivotally connected to the second conductor such that when the linkbreak 
means is pivoted away from the fuse tube in a plane extending through the 
ends of the insulator and the fuse tube, the force required to break the 
fuse link creates a moment less than the moment resulting from the 
retention force between the first conductor and the cap means. 
In a more specific embodiment of the invention, the first electrical 
conductor includes a U-shaped shield and a cantilever contact having a 
first and a second end. The first end of the cantilever contact is rigidly 
connected to the shield and biasing means extend between the shield and 
the cantilever contact for urging the second end of the cantilever contact 
away from the shield into frictional engagement and retention with the cap 
means. A detent defined by the second end of the cantilever arm receivably 
engages the cap means. The cap means includes a frustoconical portion for 
frictionally engaging and being retained in engagement with the detent in 
the cantilever contact. The linkbreak means also includes a handle which 
in use of the device is moved downwardly away from the fuse tube in a 
direction from the insulator towards the fuse tube for breaking the fuse 
link. When the fuse link is being broken the retentional force between the 
frustoconical portion of the cap and the detent is sufficient to maintain 
the cap in electrical contact with the detent. 
The foregoing has outlined rather broadly the more pertinent and important 
features of the present invention in order that the detailed description 
of the invention that follows may be better understood so that the present 
contribution to the art can be more fully appreciated. Additionally, 
features of the invention will be described hereinafter which form the 
subject of the claims of the invention. It should be appreciated by those 
skilled in the art that the conception and specific embodiment described 
may be readily utilized as a basis for modifying or designing other 
devices for carrying out the same purpose as the present invention. It 
should also be realized by those skilled in the art that such equivalent 
constructions do not depart from the spirit and scope of the invention as 
set forth in the appended claims.

DETAILED DESCRIPTION 
FIG. 1 is a side elevational view of an electrical cutout generally 
designated 10 of the present invention. The cutout 10 is electrically 
connected in series between a line terminal 12 of a line wire 14 and a 
load terminal 16 of a load wire 18. The cutout 10 includes an insulator 
generally designated 20 having a first and second end 22 and 24, 
respectively. A first electrical conductor generally designated 26 is 
rigidly secured to the upper first end 22 of the insulator 20. The first 
conductor 26 is electrically connected to the line terminal 12. A second 
electrical conductor 28 is rigidly secured to the second end 24 of the 
insulator 20 and the second conductor 28 is electrically connected to the 
load terminal 16. As shown in FIG. 1, a fuseholder 29 extends between the 
first and the second conductors 26 and 28, respectively, and consists of a 
fuse tube 30, and first and second ends 78 and 80, respectively. A fuse 
link generally designated 32 and described in more detail hereinafter 
extends through the fuse tube 30. The fuse link 32 includes a first and a 
second end 34 and 36, respectively. The second end or pigtail 36 of the 
fuse link 32 is electrically connected to the second conductor 28. Cap 
means 38 is disposed adjacent the first end 34 of the fuse link 32 with 
the cap means 38 being electrically connected to the first end 34 of the 
fuse link 32. The cap means 38 frictionally cooperates with the first 
conductor 26. A linkbreak lever means generally designated 40 for breaking 
the fuse link 32 is pivotally connected at 42 to the second conductor 28 
such that when the linkbreak lever means 40 is pivoted away from the 
insulator 20 in a reference which extends through the center of ends 22 
and 24 of the insulator 20 and the center of fuse tube 30, the clockwise 
moment created about point 42 by the force F required to break the fuse 
link is less than the counterclockwise moment about point 42 resulting 
from the retentional force RF between the first conductor 26 and the cap 
means 38. 
As shown in FIG. 1, the insulator 20 also includes an insulator support 44 
for supporting the insulator 20. The support 44 is disposed between the 
first and the second ends 22 and 44 respectively of the insulator 20. 
FIG. 1 shows the second electrical conductor 28 which also includes a first 
member 46 rigidly supported by the second end 24 of the insulator 20 and 
electrically connected to the load terminal 16. A bifurcated bracket 48 
extends from the first member 46 as shown more particularly with reference 
to FIGS. 5 and 6. 
As shown in FIGS. 2-6, a support bracket 50 is rigidly secured to the fuse 
tube 30. The support bracket 50 is pivotally secured to a second member 52 
at 54 such that the pivotal axis 42 of the second member 52 and the 
pivotal axis 54 of the support bracket 50 are spaced and parallel relative 
to each other. An anchoring means 56 extends from the second member 52 for 
anchoring the second end 36 or pigtail of the fuse link 32 in electrical 
contact with the second member 52. 
FIG. 7 shows the first electrical conductor 26 in more detail. The first 
electrical conductor 26 includes a shield 58 of U-shaped transverse 
sectional configuration and a cantilever contact generally designated 60 
having a first and a second end 62 and 64, respectively. The first end 62 
of the contact 60 is connected to the shield 58. Biasing means 66 such as 
a compression spring extends between the shield 58 and the second end 64 
of the cantilever contact 60 for urging the second end 64 of the 
cantilever contact 60 away from the shield 58 into frictional engagement 
and retention with the cap means 38. A detent 68 is defined by the second 
end 64 of the cantilever contact 60 for receivably engaging the cap means 
38. A pin 70 extends from the base 72 of the detent 68 through a hole 74 
defined by the shield 58. The pin 70 guides the movement of the cantilever 
contact 60 relative to the shield 58. 
Referring more particularly to FIG. 1, the fuse tube 30 also includes a 
first and a second end 78 and 80, respectively. The first end 78 
cooperates with the first end 34 of the fuse link 32. The first end 78 of 
the fuse tube 30 threadably engages the cap means 38 such that the first 
end 34 of the fuse link 32 is secured between the first end 78 of the fuse 
tube 30 and the cap means 38. The second end 80 of the fuse tube 30 is 
pivotally secured by the support bracket 50 to the second member 52. 
FIG. 6 shows the fuse link 32 in dashed outline. The fuse link 32 includes 
an enlarged head 82 which is disposed adjacent the first end 34 of the 
fuse link 32 such that the head 82 is secured to the first end 78 of the 
fuse tube 30 by the cap means 38. 
As shown with reference to FIG. 7, the cap means 38 includes a 
frustoconical portion 84 for engaging the detent 68. The cap means 38 also 
includes a knurled portion 86 of substantially cylindrical configuration, 
the knurled portion being internally threaded for threadably engaging the 
first end 78 of the fuse tube 30. The cap means 38 also includes a 
disc-shaped portion 88 disposed between the knurled portion 86 and the 
frustoconical portion 84. The disc-shaped portion 88 defines a pair of 
diametrically opposed cutaway segments 90 and 92 respectively. 
FIGS. 2, 3, 4 and 6, show in more detail the interrelationship of the 
various parts of the second conductor 28 and the linkbreak lever means 40. 
A third member 94 of the linkbreak lever means 40 includes a first and a 
second end 96 and 98, respectively. The third member 94 also includes a 
bifurcated portion 100 disposed at the first end 96 of the third member 94 
such that the bifurcated portion 100 is pivotally mounted at 42 such that 
the bifurcated portion 100 and the second member 52 pivot about the same 
pivotal axis. A handle 102 is disposed adjacent the second end 98 of the 
third member 94. A fourth member 103 is pivotally connected to the 
bifurcated bracket 48 and includes a guide 104 for guiding the second end 
or pigtail 36 of the fuse link 32. 
As shown in FIGS. 2, 3, 4 and 6, the fourth member 103 includes a movable 
fulcrum point 106 for breaking the fuse link 32 when the handle 102 is 
moved away from the fuse tube 30 in the aforementioned reference plane 
passing through the first and second ends 22 and 24, respectively of the 
insulator 20 and the fuse tube 30. The fourth member is pivoted about 
pivot point 42 by the interengagement of the bifurcated portion 100 with 
the guide 104. 
As shown in FIGS. 2, 3, 4 and 6, the support bracket 50 further includes a 
hook-shaped portion 108 which extends from the support bracket 50 towards 
the linkbreak lever means 40. A stop 110 extends from the fourth member 
103 such that when the fuse link 32 is secured to the anchoring means 56, 
movement of the linkbreak lever means 40 towards the insulator 20 in the 
reference plane results in the stop 110 abutting against the hook-shaped 
portion 108 thereby forcing the cap means 38 into frictional engagement 
and retention with the detent 68. 
As will be evident to those skilled in the art, the relative dispositions 
of the pivotal axis 42 and 54 is such that movement of the linkbreak lever 
means 40 away from the fuse tube 20 in the plane P imparts a component 
force to the pivotal axis 54 to urge the frustoconical portion 84 of the 
cap means 38 into increased frictional engagement with the detent 68 due 
to the increased tension along the fuse link 32 resulting from the 
movement of the linkbreak lever 40 during the breaking of the fuse link. 
FIG. 9 is a sectional view of a prior art cap means 38 having a 
semispherical portion 72 for engagement with a standard detent 68 of the 
contact 60. FIG. 8 is a perspective view of the improved cap means 38 
showing the frustoconical portion 84, the knurled portion 86 and the 
disc-shaped portion 88. The disc-shaped portion 88 includes diametrically 
opposed cutaway segments 90 and 92, respectively. 
FIG. 10 is a vector diagram showing the various force components acting on 
the cap means 38. FIG. 10 is an exaggerated contact profile showing the 
inside and outside radii divided by an intersecting line I. Above the 
intersecting line I, the force F on the cap to resist unlatching starts 
nearly vertical and rotates clockwise as the cap moves down the contact 
profile. At the intersecting line I, the force F is at its maximum 
clockwise position and begins to rotate counterclockwise as movement is 
continued along the contact profile beyond the intersecting line. 
Resolving the force F into its vertical and horizontal components Fy and 
Fx respectively reveals that the components will vary in magnitude as the 
force F rotates along the contact profile. The horizontal component Fx of 
this force F coupled with the moment arm creates the resistance to the 
unlatching moment caused by downward movement of the handle of the 
linkbreak lever. 
The cap means 38 of the present invention provides a point of contact 
between the frustoconical portion 84 and the detent 68 and this point of 
contact and the force is above the intersecting line I thereby providing 
the maximum resistance to the unlatching moment whereas with the prior art 
semispherical cap profile, the force F acts at or somewhat below the 
intersecting line I resulting in a lesser and continually decreasing 
resistance to the unlatching moment. 
The present invention utilizes the shape of the cap means to provide forces 
in the design directions but also creates greater magnitude forces than 
the prior art semispherical caps by being slightly taller and having a 
sharp corner to allow a somewhat higher co-efficient of friction. The 
taller shape of the cap of the present invention allows the cap to project 
further into the detent 68 providing a slightly longer moment arm than the 
prior art (i.e. spherical) cap thereby further increasing the resistance 
to the unlatching moment. 
As shown in FIG. 10, the detent profile includes a point P intersected by 
the intersecting line I. At this point P of the profile the force Fy 
exerted by the spring 66 is relatively small whereas the force Fx 
representing the force tending to pull the cap means out of engagement 
with the detent 68 is relatively large. However, at the point of contact 
PC between the edge of the frustoconical portion 84 and the detent, the 
force Fy is relatively large and the force Fx relatively small. In view of 
this, it is evident that the vector forces exerted on the portion 84 
during movement of the portion 84 from PC to P are relatively great which 
enables the cap to be retained in the detent during linkbreak operations. 
However, in the prior art, the vector forces from the point P 
progressively rotate in a counterclockwise direction and the force 
imparted to the cap due to the linkbreak operation easily disengages the 
cap from the detent. 
Operation of the electrical cutout of the present invention enables the 
fuse link 32 to be easily broken by the application of a downward force to 
the handle 102 in a direction away from the fuse tube 30 and in the 
reference plane. 
With the prior art cutouts of this type, it has previously been necessary 
to incorporate at the first end 78 of the fuse tube 30 a relatively 
complex positive latch arrangement for insuring that the cap 38 does not 
disengage from the first conductor 36 during such linkbreak operation. The 
present invention provides a novel configuration of the cap means 38 to 
increase the frictional and retentional engagement force between the 
frustoconical portion 84 of the cap means 38 and the detent 68. The 
angular edges of the frustoconical portion 84 as opposed to the prior art 
semispherical configuration of the cap provides the necessary increased 
retentional engagement between the cap and the detent thereby avoiding the 
necessity of providing a costly positive latch mechanism. At the same 
time, the linkbreak mechanism of the present invention provides a 
linkbreak lever means 40 having a handle 102 that extends to a location 
that is easily accessible to the lineman such that the lineman with the 
aid of a line pole may easily engage the handle and pull the same 
downwardly to firstly break the fuse link 32 and secondly thereby permit 
the disengagement of the frustoconical portion 84 from the detent. 
The present invention not only provides an electrical cutout which avoids 
the need of a costly positive latch mechanism but also provides a 
linkbreak lever which is located in an ideal position for operation by a 
lineman. 
The frustoconical portion of the cap means as compared with the prior art 
semispherical cap provides the following advantages. Firstly, when such a 
frustoconical portion is used, the cutout does not require a positive 
latch mechanism, therefore the number of parts required in the fabrication 
of the cutout is reduced thereby reducing the costs. 
Secondly, when a frustoconical cap is used as a part of the invention, a 
standard fuseholder or a linkbreak fuseholder may be used interchangeably 
in a cutout employing a detent-type cantilever contact. 
Thirdly, the handle being positioned in the same plane as the insulator to 
the fuse tube for pulling in a downwardly direction is ideal for obtaining 
safest operating direction when breaking the link. 
Fourthly, the handle is easily accessible in the front disposition thereof 
from a variety of different servicing positions. 
The present disclosure includes that contained in the appended claims as 
well as that of the foregoing description. Although this invention has 
been described in its preferred form with a certain degree of 
particularity, it is to be understood that the present disclosure of the 
preferred form has been made by way of example and that numerous changes 
in the details of construction and the combination and arrangement of 
parts may be resorted to without departing from the spirit and scope of 
the invention.