US3345483A

US3345483A - Removable current limiting fuse

Info

Publication number: US3345483A
Application number: US453754A
Authority: US
Inventors: Merrill G Leonard; Leonard L Wright
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1965-05-06
Filing date: 1965-05-06
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03
Also published as: JPS4528854Y1

Description

1967 M. G. LEONARD ETAL 3,

REMOVABLE CURRENT LIMITING FUSE Filed May 6', 1965 2 Sheets-Sheet 2 O 77 78 y 5 79 FIG. 2.

If) no In I09 1 H4 98 FIG. 3]

I43 [3a 150 I39 United States Patent 3,345,483 REMQVABLE CURRENT LIMITWG FUSE Merrill G. Leonard, Brookfield Township, Fowler, Ohio,

and Leonard L. Wright, Sharon, Pa, assignors to Westinghouse Electric Corporation, Pittsburgh, Pa, a corporation of Pennsylvania Filed May 6, 1965, Ser. No. 453,754 6 Claims. (Cl. 200-133) This invention relates to improvements in electrical circuit protective devices, and more particularly to a fuse especially suitable for use with a transformer and adapted to be mounted in a bushing extending through the wall of the transformer housing.

Heretofore, the proper fusing of a transformer to protect the transformer from overload or a short-circuit fault has usually required either that the fuse be located at some distance from the transformer, or that the transformer housing have cover plates or other closable apertures therein so that the fuse could be reached when it was necessary to replace it. Neither one of these expedients represents a satisfactory solution to the problem of fusing a transformer; fuses external to the transformer housing require additional circuit wiring and are therefore expensive; doors in the transformer housing which must be opened to reach a fuse result in service difliculties, and also increase the problem of hermetically sealing the transformer to protect it from moisture and other atmospheric conditions.

The removable current limiting fuse of our invention overcomes these and other disadvantages of the prior art. We provide a current limiting fuse which is mounted inside a bore in a bushing mounted in and extending through the transformer casing, one electrical connection being made to the fuse at the inside end of the bushing, the other electrical connection being made to the fuse at the exterior end of the bushing. In all of the embodiments of our invention, the circuit may be broken by the use of a hook stick to manipulate a release lever located at the outer end of the bushing, the release lever forming a part of the electrical circuit to the adjacent end of the fuse, a spring lift exerting force against the inner end of the fuse thereafter pushing the fuse partly out of the bore in the bushing and making the end of the fuse readily accessible. In some embodiments of our invention the fuse is attached to the release lever to form a hook stick drawout, so that circuit may be broken and the fuse released by use of a hook stick, and the fuse may then be drawn out by further manipulation of the release lev-er by the hook stick.

In further summary, our invention includes a current limiting fuse mounted in the bore of the bushing. One end of the bushing has a cap mounted thereon; a spring withint he bore of the bushing pushes against the cap and exerts a force on the adjacent end of the fuse. At the other end of the bushing, a release lever has one end hinged on a mounting bracket which is permanently secured to the bushing, and the other end of the release lever is normally held in place in a latched position by a detent mechanism, part of which is also permanently attached to the end of the bushing. The release lever has a large eye, so that a hook stick may be used to move the release lever out of the latched position, or into the latched position. In two embodiments of our invention, a weather cap secured to the release lever substantially seals or covers the bore opening in the adjacent end of the bushing when the release lever is in its latched position. The weather cap may have a boss extending therefrom which exerts pressure on the adjacent end of the fuse to force it inward against the tension of the aforementioned spring. In another embodiment, the adjacent end of the fuse has a stud or arm extending therefrom with a *bore therein into which passes a boss or pin extending from the release lever, so that when the release lever is moved upward or away from the bushing it draws the fuse with it. In still anothr embodiment of our invention an expansion collar composed of rubber or other resilient material, located adjacent the end of the fuse which adjoins the release lever, is expanded by an inwardly extending member attached to the release lever, the outer wall of the collar after expansion pressurally engaging the inner wall of the bore in the housing. In a fourth embodiment of our invention, an O-ring effectively hermetically seals the space within the bushing bore.

Accordingly, a primary object of our invention is to provide new and improved current limiting fuse apparatus especially suitable for use with a transformer.

Another object is to provide a new and improved fuse adapted to be mounted in a bore in a bushing and adapted to be withdrawn by the use of a hook stick.

Another object is to provide a new and improved fuse suitable for mounting in a bore in a bushing and having means for sealing the bore while the fuse is disposed therein.

These and other objects will become more clearly apparent after a study of the following specification, when read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a cross-sectional view of a fuse and bushing according to one embodiment of our invention;

IG. 2 is a fragmentary sectional view of a fuse and bushing according to the preferred embodiment of our invention;

FIG. 3 is a fragmentary sectional view of a fuse and bushing according to a third embodiment of our invention; and

FIG. 4 is a fragmentary sectional view of a fuse and bushing according to a fourth embodiment of our invention.

Reference is made now to the drawings, in which like reference numerals are used throughout to designate like parts. Paying particular attention to FIG. 1, a bushing generally designated 10 has a bore 11 extending therethrough, the bushing being threaded at 12 on the exterior surface thereof and being mounted in an aperture 13 in a transformer tank 14. Near the inner or lower end 15 of the bushing there is an annular groove 16 in the outer wall thereof, and disposed over the end 15 of the bushing is a cap 17 having an annular ridge or tongue 18 which fits in the aforementioned groove 16 and retains the cap in position on the end of the bushing.

An elongated fuse generally designated 20 is disposed in the bore 11, the fuse 20 having a tube 21 of insulating material and caps or

ferrules

22 and 23 of conductive material. A spring 25 is disposed in the bore 11 between the lower cap 23 and the inside wall of the cap 17.

Lead or conductor 26 is connected to the aforementioned cap 17 and is secured thereto as by soldering.

The other or outer end 28 of the bushing has an annular groove 29 in the outer wall thereof, and mounted upon the end 28 of the bushing is a short sleeve 31 having an annular tongue or ridge 32 extending into the groove. The sleeve 31 has an arm 41 on one side of the bushing; mounted thereon and if desired formed integrally therewith and extending in a direction parallel to the axis of the bushing is a terminal post generally designated 34 having two parallel arms, one of the arms being shown at 39, the other of the arms not being shown for convenience of illustration, the arms being spaced from each other and having pin 38 extending therebetween, the end of the release lever 36 having a bore 40 therethrough and being hinged about the pin 38 extending between the two arms of the terminal post.

Preferably diametrically opposite to the aforementioned terminal post 34 and arm 41 is an additional arm 42, extending from the sleeve 31, arm 42 having two spaced upright portions, one of these upright portions being shown at 43, having a detent at 45 cooperating with a properly surfaced area on the aforementioned release lever 36 to form a latch. Release lever 36 is seen to have a wide portion 47 with an eye 48 therein.

It is seen that the release lever 36 has a relatively pointed end 49 which may, with adjacent spaced conductive member 50 connected to ground 46, form a spark gap 51.

On the underside of the aforementioned release lever 36 there is disposed a weather cap 53 which may be composed of conductive material, and which has a boss or protruding portion 54 of conductive material centrally thereof, which presses against the cap 220i the fuse, and has an overhanging lip portion 55 which, while the release lever 36 is in the position shown very snugly fits the endof the bushing and for all practical purposes closes, or forms a seal or cover for the bore therein. The

electrical circuit to fuse cap 22 includes boss 54, lever 36, post 34 and lead 37.

In the operation of the apparatusrof FIG. 1, assume that the current limiting fuse generally designated 20 has opened the circuit because of a fault current or a sustained overload. The eye 48 of the release lever 36 is then grasped by a hook stick or other convenient means and moved upwardly as seen in the figure, the right-hand end of the lever 36 hinging about the pin 38, and the lever 36 may be-moved to a substantially vertical position, in which position the fuse 20'is readily withdrawable from the bore 11 in the bushing past the release lever. When the arm 36 is raised, the spring 25 forces/the fuse upwardly making it easy to grasp the upper end of the fuse and remove it from the bore 11. After a new fuse is inserted, movement of the lever arm 36 downward causes the protruding portion 54 to press against the cap 22 of the new fuse, the new fuse is forced down against the tension of spring 25 forming a secure electrical circuit between the

leads

26 and 37, and the lever arm 36 is thereafter latched at detent 45.

Particular reference is made now to FIG. 2, in which a second embodiment of the invention is shown. In 'FIG. 2, the bottom portion of the fuse and bushing assembly, not shown, may be substantially similar to that of FIG. 1. The short sleeve 31' is seen to have a terminal post 64 which has an inwardly extending boss or lip portion 65, with a flat under surface curving as shown. Lead 61 is connected to post 64. A release lever 66 has the right-hand end 67 thereof fitting underneath the lip portion 65, and end 67 is held snugly against the portion by the pressure of spring 25, not shown for convenience of the illustration, when end 69 of the release lever 66 is latched at detent in upright 63. The release lever 66 has two pins extending from the sides thereof, one of these pins being shown at 76. It is seen that secured to the upper cap or ferrule 22' of fuse 20' are two arms, one of these arms being shown at 77, the arm having an aperture 78 therein through which the pin 76 passes. The weather cap 79 as before closes or covers the upper end of the bore 11 in the bushing while release lever 66 is in the latched position shown.

In the operation of the apparatus of FIG. 2, assuming that the fuse generally designated 20 has opened the circuit, the eye 68 in wide portion 71 of the lever 66 is grasped as by a hook stick and raised upwardly. End 67 of lever arm 66 moves away from the adjacent portion 65 of post 64, and the arm 77 is carried with pin 76, carrying with it the fuse 20. A new fuse may be attached to the release lever 66 and thereafter the entire assembly inserted in the bore in the bushing, the end 67 of lever 66 being thereafter hooked under lip 65, and the end 69 of lever 66 thereafter being brought down to secure the catch at detent 75, an electrical circuit being formed between

leads

26 and 61 through the fuse.

Particular reference is now made to FIG. 3, where a third embodiment of the invention is shown. Bushing has bore 91 therethrough in which a fuse 92 having an upper terminal cap or ferrule 93' is located. The lower end of the fuse, spring 25- and cap 17 are not shown for convenience of illustration. A sleeve 95 secured to the end of the bushing by the tongue and groove arrangement shown has oppositely extending

arms

96 and 97, arm 97 having two upright posts extending therefrom, one of these posts being shown at 98, the other post not being shown for convenience of illustration, and at the upper end of the post 98 is a cross bar 99 extending between the posts. Lead 94 is connected to arm 97.

A release lever 102 has the right-hand end thereof shaped as at 103 to form with the bar 99 a combined catch and pivot point. Lever 102 has portion of enlarged width 107 with eye 108 therein. End 109 of lever 102 is arranged to cat-ch or latch with the detent 105. Extending from the lower side of the release lever 102 is an arm 110 having a plunger portion of enlarged diameter 111 which, when the lever 102 is pressed down in the position shown, passes partially into the central aperture or bore 112 of a resilient member or expansion collar 113, forcing the outer surface of resilient member 113 into firm engagement with the inner wall of bore 91 at or near the end of the bushing. Resilient member 113 is secured as by cement or other suitable means, not shown, to the cap or ferrule 93 of fuse 92.' The resilient member 113 has a plate 114 of conductive material on the top thereof with an extended stud 115 of conductive material; the upper end of the stud 115 forms a pivot point for the release lever 102, and also provides a means-by which force is transmitted from lever 102 to fuse 92 to force the fuse into the bore 91 against the tension of spring 25. Lead 118 passing through bore 119 in expansion collar 113 electrically connects ferrule 93- to stud 115.

In the operation of the apparatus of FIG. 3, assume that the fuse 92 has blown because of some overcurrent or fault condition, then the eye 108 of release lever 102 is grasped as by a hook stick and moved outward and upward. Pressure retains the plunger portion 111 firmly in the bore 112 in expansion collar or resilient member 113, carrying the fuse with it as the lever 102 is moved upward response to motion of the hook stick. The aforementioned end 103 of lever 102 slides underneath the cross bar 99 so that the entire lever'102 with the fuse 92 attached may be withdrawn from the bushing. Upon inserting a new fuse, the fuse is dropped into place in the bore 91, the end 103 of lever 102 is hooked under the bar 99, and thereafter downward motion of the hook stick caught in eye 108 moves the end 109 of lever 102 to a latching position in detent 105. The electrical circuit to ferrule 93 'is made by way of lead 118, plate 114, stud 115, leverarm 102, cross bar 99, post 98 to lead 94.

Expansion collar 113 forms a substantially hermetical seal for the end of bore 91. 7

Particular reference is made now to FIG. 4 where a fourth embodiment of the invention is shown. In FIG. 4, bushing 128 has a sleeve 1129 on the end thereof with an arm 130 having a post portion 131 with detent 132. The bore 134 in bushing 128 has a portion 135 of enlarged diameter at the end thereof in which is mounted and secured a collar 136 having an upwardly extending hook portion 137 with an overhanging lip portion 139, the lip portion 139 engaging end 142 of release lever 143, release lever 143 having portion of enlarged thickness 144 with eye 145 therein. The fuse 146 has an upper cap 147 with at least one upwardly extending arm or post 148 having an aperture 149 through which passes a pin 150 secured to release lever 143. The aforementioned collar 136 has an annular groove 152 on the inside surface thereof in which is disposed an O-ring 153 forming sealing engagements with collar 136 and ferrule 147. In FIG. 4, the lower ends of the fuse 146 and bushing 128, together with spring 25, are not shown for convenience of illustration.

Lead 141 is connected to collar 136 which is composed of conductive mate-rial.

In the operation of the apparatus of FIG. 4, the fuse 146 while in position in the bore 134 is held against the tension of spring 25 by the force which pin 150 exerts upon arm 148. Sealing is provided by the O-ring 153 in groove 152. After the fuse 146 blows, the release lever 143 is grasped by hook stick in eye 145 and lifted upward carrying with it the arm 148 and the fuse 146. To reinsert a new fuse, the fuse is dropped into the bore 134, end 142 of lever 143 is hooked under lip 139, and thereafter force at eye 145 moves the end 159 of the lever downward until the lever arm is latched at the detent 132.

The term pivot means as employed in the claims appended hereto is used generically to designate the pin 38 and bore 40 arrangement of FIG. 1, the lip 65 and lever end 67 arrangement of FIG. 2, the cross bar 99 and shaped lever end 103 arrangement of FIG. 3, and the lip 139 and shaped lever end 142 arrangement of FIG. 4.

Whereas we have shown and described our invention with respect to some embodiments thereof which give Satisfactory results, it should be understood that changes may be made and equivalents substituted without departing from the spirit and scope of the invention.

We claim as our invention:

1. Releasable fuse apparatus including in combination a bushing having a bore therethrough, a collar extending from one end of the bushing, spring means at one end of the bushing disposed in the bore for pressing the fuse partially out of the bore at the other end of the bushing when the fuse is released, movable release lever means operatively connected to said other end of the bushing and adapted to maintain the fuse in the bore in the bushing against the tension of the spring means, and means cooperating with the release lever means and the bushing for substantially closing the adjacent end of the bore while the fuse is in its normal position in the bore in the bushing, said collar having an annular groove on the inside surface thereof, the fuse having a cap at each end thereof, and an O-ring composed of resilient material disposed partially in said groove and effecting a seal between the collar and the adjacent cap of the fuse.

2. Releasable fuse apparatus including in combination a bushing having a bore therethrough, a fuse mounted in said bore, spring means at one end of the bushing disposed in the bore for pressing the fuse partially out of the bore at the other end of the bushing when the fuse is released, movable release lever means operatively connected to said other end of the bushing and adapted to maintain the fuse in the bore in the bushing against the tension of the spring means, means cooperating with the release lever means and the bushing for substantially closing the adjacent end of the bore while the fuse is in its normal position in the bore in the bushing, an expansion collar secured to the end of the fuse adjacent the release lever means, the expansion collar having an axially extending passageway therethrough, stud means mounted upon the expansion collar and forming a pivot point for the release lever means, and a plunger member secured to the release lever means and extending into the central aperture of the expansion collar, the release lever means forcing the plunger into the aperture and forcing the outer wall of the expansion collar against the inner wall of the bore to form a seal for the bore in the bushing.

3. Fuse apparatus comprising, in combination, a bushing having an axial bore therethrough, a fuse disposed in said bore, terminal means at one end of the bushing, spring means disposed in the bore exerting a force between the terminal means and the adjacent end of the fuse and normally tending to force the fuse partially out of the bore in the bushing, pivot means mounted on the other end of the bushing, a movable release lever operative-1y connected to the last-named end of the bushing and pivoting about the pivot means, latching means for holding the release lever in a position whereat the fuse is maintained in the bore in the bushing against the force of the spring means, a collar on said bushing at the end thereof adjacent the latching means, said collar having an annular groove therein, and an O-ring located in said groove and pressing against the adjacent end of the fuse.

4. Fuse apparatus comprising, in combination, a bushing having an axial bore therethrough, a fuse disposed in said bore, terminal means at one end of the bushing, spring means disposed in the bore exerting a force between the terminal means and the adjacent end of the fuse and normally tending to force the fuse partially out of the bore in the bushing, pivot means mounted on the other end of the bushing, a movable release lever operatively connected to the last-named end of the bushing and pivoting about the pivot means, latching means for holding the release lever in a position whereat the fuse is maintained in the bore in the bushing against the force of the spring means, resilient means attached to the fuse, and means carried by the release lever for forcing the resilient means into firm engagement with the inner wall of the bore to seal the bore in the bushing.

5. Fuse apparatus comprising in combination, a bushing having a bore therethrough, an elongated fuse disposed in the bore, spring means disposed in the bore at one end thereof and normally urging the fuse out of the bore, release lever means at the other end of the bushing adapted to be grasped by a hook stick, means securing the release lever means to the fuse whereby when the release lever means is moved in response to motion of the hook stick, the release lever means carries the fuse with it, the fuse having resilient means on the end thereof adjacent the release lever means, the release lever means carrying means adapted to engage the resilient means and carry the fuse with the release lever means when the release lever means moves.

6. Fuse apparatus comprising, in combination, a bushing having a bore therethrough, an elongated fuse disposed in the bore, spring means disposed in the bore at one end thereof and normally urging the fuse out of the bore, release lever means at the other end of the bushing adapted to be grasped by a hook stick, means securing the release lever means to the fuse whereby when the release lever means is moved in response to motion of the hook stick the release lever means carries the fuse with it, the release lever means having at least one pin extending from the side thereof, the fuse having an arm extending therefrom with an aperture therein adapted to cooperate with the pin, whereby movement of the release lever means carries the fuse with it.

References Cited UNITED STATES PATENTS H. B. GILSON, Assistant Examiner.

BERNARD A. GILHEANY, Primary Examiner,

Claims

1. RELEASABLE FUSE APPARATUS INCLUDING IN COMBINATION A BUSHING HAVING A BORE THERETHROUGH, A COLLAR EXTENDING FROM ONE END OF THE BUSHING, SPRING MEANS AT ONE END OF THE BUSHING DISPOSED IN THE BORE FOR PRESSING THE FUSE PARTIALLY OUT OF THE BORE AT THE OTHER END OF THE BUSHING WHEN THE FUSE IS RELEASED, MOVABLE RELEASE LEVER MEANS OPERATIVELY CONNECTED TO SAID OTHER END OF THE BUSHING AND ADAPTED TO MAINTAIN THE FUSE IN THE BORE IN THE BUSHING AGAINST THE TENSION OF THE SPRING MEANS, AND MEANS COOPERATING WITH THE RELEASE LEVER MEANS AND THE BUSHING FOR SUBSTANTIALLY CLOSING THE ADJACENT END OF THE BORE WHILE THE FUSE IS IN ITS NORMAL POSITION IN THE BORE IN THE BUSHING, SAID COLLAR HAVING AN ANNULAR GROOVE ON THE INSIDE SURFACE, SAID COLLAR HAVING AN ANNULAR GROVE ON THE INSIDE AND AN O-RING COMPOSED OF RESILIENT MATERIAL DISPOSED PARTIALLY IN SAID GROOVE AND EFFECTING A SEAL BETWEEN THE COLLAR AND THE ADJACENT CAP OF THE FUSE.