US2621270A - Fuse cutout - Google Patents

Description

Q 1952 A. w. EDWARDS 2,621,270

FUSE CUTOUT Filed June 23, 1949 WITNESSES: INVENTOR a- BY Q 1% AndrewW. Edwards.

Patented Dec. 9, 1952 FUSE CUTOUT Andrew W. Edwards, 'East McKeesport, Pa., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 28, 1949, Serial No. 100,868

9 Claims.

viding a tensioned fuse cutout in which the fuse 1 link thereof is easily inserted or removed and is effectively supported in the conductive position.

A further object of this invention is the provision of a strong and mechanically simple fuse cutout which affords physically stable support for the fuse link thereof when operating under normal current conditions, and which promptly snaps to circuit interrupting position upon encountering excessive current across the link.

Another object of the present invention is the provision of a tensioned fuse cutout which is easily constructed, and is highly satisfactory when installed.

A still further object of this invention is that of providing an inexpensive and practical tensioned fuse cutout such as may be installed on power transmission line poles, towers, transformers, or the like.

Another object of this invention is the provision of a satisfactorily electrically conductive tensioned fuse cutout.

A further object of the present invention is that of providing simple and readily produced tensioning means for a tensioned fuse cutout.

From the standpoint of function, tensioned fuse cutouts are intended to arrest the flow of current by spending a fusible electrically conductive or heat-sensitive portion in response to overload current, thereupon opening a related electrical line with a snap action. A variety of these cutouts employ contact arms, which support a fuse link including the fusible portion and are biased in favor of pulling the leads of the fuse apart when fusion occurs, thus to extend the opening of the transmission line circuit and decrease the danger of arcing. To restore the cutout to electrically conductive position in the power line, a replacement fuse of desired rating is tensioned between the contact arms, and this remains in tension until current overload is encountered to release the bias of the arms in favor of separation as already described.

Tensioned fuse cutouts have come into demand in such important fields as the outdoor transmission of electrical power, and are often used on line towers, poles, transformers, or the like, thus to afford a protective component of the power transmission system. Among these systems are those employed for rural electrification, which are mentioned here as an example illustrating certain conditions and economic levels of use of the cutouts. Then, too, it will be appreciated that the quantity of cutouts needed in a particular system may be quite large and that their unit cost accordingly becomes a highly important factor.

There are quite a number of heretofore known circuit interrupters or tensioned fuse cutouts which involve such considerations as failure to lend themselves readily to mass production techniques. In certain instances many of the parts employed for making the cutouts are difficult to produce and assemble, and even then sometimes are instrumental to poor quality and inferior performance of the resulting product. In producing the cutouts, it is frequently advantageous to weld together adjacent parts which are to convey the line current, but the very shape or arrangement of these parts often makes welding or other forms of assembly a very time-consuming operation. A variety of cutouts include contact arms and biasing springs made of Wire and these arms usually take the form of trusses to afford strength, but arms of this sort usually are unwieldy to produce and assemble.

There are heretofore known cutouts, too, which once installed, offer an extremely unfavorable aspect of upkeep. In this connection, it will be appreciated that certain of these cutouts, because of the precise character and arrangement of their parts, are very tedious to reset or service from a safe distance with a suitable tool as in replacing a spent fuse. The contact arms and biasing means in these devices so often have extremely poor lateral stability and thus are troublesome to reset to operating position with a tool. At times, this fallacy adds to the occupational hazards of linemen who, for example, service the cutouts from a selected position on a transmission line pole or tower under conditions which are already adverse to absolute safety.

A further object of this invention accordingly is the provision of a practica1 and reliable tensioned fuse cutout which is easy to produce and simple to service and maintain.

A still further object of the present invention is that of providing a strong and easy to assemble tensioned fuse cutout having simplicity of structure, a Well directed biasing action and good lateral stability of the contact arms.

The preceding objects and other objects of this invention will become more apparent upon consideration of the following description of certain preferred embodiments thereof, when taken in connection with the accompanying drawing, in which:

Figure 1 represents in side elevation, a tensioned fuse cutout having features in accordance with the invention;

Fig. 2 is a top plan view depicting details of the apparatus noted in Fig. 1;

Fig. 3 is a fragmentary plan view of the lower contact arm of the apparatus in Fig. 1;

Fig. 4 is a perspective view representing in detail a terminal component of the apparatus in Fig. 1; and

Fig. 5 is a fragmentary plan view of a modified form of the apparatus in Fig. 3.

In the particular embodiment of the invention disclosed in the accompanying drawing (Figs. 1 to 4 inclusive), there is provided a tensioned fuse cutout I which comprises an electrical insulator II and relatively movable contact arms I2 and I3 supporting a fuse link It which electrically interconnects these arms.

1 The cutout I 8 further inc udes line terminals I6 and I! individually corresponding to the contact arms I2 and I3, respectively, for connection of the cutout into a power line of an electrical transmission system. Terminals I6 and ii are in electrically conductive relation with each other through the fuse link Id and fusibl portion 32 of the latter, so long as the fuse link remains conductive. The relatively movable contact arms I2 and I3 serve to impose tension on the fuse link I4 and separate the free ends of the fusible portion 34 when this is melted or softened by heat of an overload current in the power transmission line. In order to tension the link I5, the contact arm I2 includes electrically conductive spring means I5 having features which will be explained more fully hereinafter. This spring means I6 in effect affords a pivot for displacement of contact arm I2 relative to arm I3. The contact arm I3 preferably is substantially fixed in position relative to the insulator I I.'

The insulator II illustratively is oblong in shape as for mounting with the major axis in the upright position, and conveniently is round or substantially circular in transverse section. It is made of porcelain, glass, or of any other suitable dielectric. The long dimension of the insulator II- is useful for giving an effective spacing of the inner ends of the contact arms I2 and I3 which is desired to keep the electrical transmission line open after the fuse link I4 is expended. Contact arm I3 is made of electrically conductive material such as cobalt-beryllium-copper alloy or copper-clad steel, and advantageously is in the form of a substantially rigid metal strip having the larger dimension of its transverse cross-section substantially lateral to the longitudinal axis of the insulator II and substantially lateral to the desired direction of support of fuse link I4. At the outer end remote from the insulator II, the contact arm I3 conveniently is longitudinally split, and the resulting portions turned or bent back to give integral hooks I3b and [30 on opposite sides of this arm for receiving and holding the fuse link I 4. Each of the hooks preferably extends backward and in the backward position diverges from the adjacent edge of the main body of the related contact arm. An outer portion I3a of the contact arm I3, including the hooks, is preferably inclined from the plane of a rearward portion I3d and toward the outer end of contact I2, thus to enhance the receiving and holding eiiect on fuse link I4.

At the inner end adjacent to the insulator II, contact arm I3 preferably is bent away from its corresponding support I9 to provide the terminal I'I, this having an opening Ila for receiving a power line fastening device Ill). The fastening device IIb illustratively is a bolt and corresponding nut, the bolt having its shank inserted through opening Fla and welded at the head to the adjacent terminal portion of contact arm I3 so as to assure adequate electrical conductivity at this point. For the sake of ease of production and for affording a continuous electrical path, the contact arm I3 advantageously is one continuous integral strip inclusive of th hooks I 312 and I30.

Support I9, for example, is a substantially rigid metal strip fixed to a corresponding end portion I I0 of the insulator I I, the long dimension of the transverse cross section of this strip being substantially lateral to the longitudinal axis of the insulator. The insulator end portion IIc illustratively has a transverse opening into which the support I9 is inserted and cemented in place.

A bolt 22 conveniently extends through aligned openings in the contact arm I3 and support I9 to fasten these portions together as with the aid of a corresponding nut 23. Contact arm I3 and support I9 thus, for example, are held together fiat-face to flat-face, the bolt 22 being disposed outward of the bent-away portion of this arm including the terminal I'I. Also, the bolt 22 is preferably received in the corresponding opening in support I9 at a point sufiiciently far out from the insulator end portion II c to hold the contact arm I3 and terminal I1 clear of the insulator body. If desired, several bolts, such as the bolts 22, may be employed for fastening to gether the contact arm I3 and support I9. Usually, though, one bolt is adequate and savings in material thus can be had, especially with the aid of an interlock 2! in which, for example, a protuberance such as pressed tip 21a associated with the arm I3 rests in a slot 211) in the support I9 to prevent relative rotation of the arm and support about the single bolt 22. As an alternative, it will be appreciated that in certain instances the contact arm I3 and the related support I9 may be welded together.

The contact arm I2 illustratively has an outer portion 26, joined as by riveting and welding to the spring biasing means I5 thereof. This outer portion 26, for example, is made of a substantially rigid strip of electrically conductive material such as copper alloy or copper-clad steel. At the outer end, the portion 26 is provided with means for receiving and holding the fuse link l4, such as hooks 26c and 26d in zone 262 which is inclined from the plane of a rearward zone 26b and toward the outer end of contact arm I3, thus to enhance the receiving and holding effect on fuse link I4. The hooks 26c and 26d conveniently are formed by longitudinally splitting the outer end of portion 26 and turning or bending back the split portions in substantially the same plane as zone 26a. Hooks 26c and 26d, in the backward position, preferably diverge from the adjacent sides of the main body of portion 26 for easier admission of the fuse link I4 and better contact therewith.

The biasing spring means I6 (Fig. 3) advantageously includes a main portion 15a and extension portions I5b and I50 and is of electrically conductive material. A considerable advantage is had by making the spring means I5 from sheet metal or the like, both from the standpoint of production and effective performance in the cutout I0. Thus, for example, in producing the spring means a flat sheet of spring copper aly metal or other electrically conductive material of suitable spring quality is subjected to a die stamping or cutting operation to give a bifurcated metal blank including the main portion lie and the extension portions I52) and I50. The blank so producedillustratively is a substantially Y-shaped piece '(Fig. 3) wherein the extension portions I5b and I50 are, for example, substantially parallel and spaced apart to produce a gap therebe-tween which is somewhat wider than the width of the main portion I 5a. Following the stamping or cutting operations, the main portion I 5a, for example, is subjected on the fiat sides thereof to a rolling or shaping procedure, this usually beginning at the point of bifurcation and going outward along the main portion I5a to render the spring means intermediately convolute at zone |5d (Fig. 3). In certain instances instead of actually rolling or deforming the metal blank to produce the convolute zone I5d, the main portion I5a is merely wound one or more turns in the proper direction through the space between extensionportions I 50 and I5d and is assembled in the cutout ID to give the desired bias.

For connecting the contact arm I2 with the insulator II, there is, for example, a support I8, this illustratively being a substantially rigid metal strip having the inner end thereof introduced in a transverse opening in the insulator end portion He and cemented in place. This support conveniently is a straight rigid piece having the longer dimensions of its transverse cross section substantially lateral to the longitudinal axis of the insulator II. An angular terminal I 6 of the contact arm I2 has a leg Ilia to which the free ends of extension portions I5b and IE0 of the spring biasing means are conveniently secured. For this purpose, the angular terminal I6 is provided with opposed slots I60 and IGd at the apex of the angle thereof for individually receiving the corresponding extension portions I51) and I50 and admitting the same to the underneath side of leg I611. The extension portions I51) and 150 conveniently are welded to the underneath side of leg I6a of the terminal I6. An opening IGe extends through leg I6a, such as between the points of welding the portions I52) and IE0, and receives a bolt (Fig; 1) which passes through a corresponding opening in support I8 thus to fasten the several elements together with the aid of a nut 2 I. Leg IGb of the angular terminal I6 illustratively is at about right angles to the leg IBa and conveniently affords edges along the slots I60 and Mid which give cantilever support of the contact arm I2, and more especially of the extension portions I5b and I5c thereof. A connector IS on the terminal I6, illustratively comprising a bolt and nut, with the bolt extending through an opening IBg in the leg IISb and welded thereto at the head, receives a corresponding end of the power transmission line. The terminal I6, as mounted, preferably is substantially clear of the insulator end portion I Ib and away from the spring biasing means I5 and outer portion 26 of the contact arm I2.

Main portion I5a of the spring biasing means I5 illustratively overlaps'the outer portion 26 of contact arm I2 and the overlapping portions are riveted and welded together. The outer ortion 26 preferably extends outward in the same general direction from the insulator as does the main portion I5a of the spring means I5. By producing welded joints in the contact arm I2, as between the angular terminal I6 and extension portions I5?) and I50, and as between main portions I5a and outer portion 26, an electrically continuous member is successfully assured. It will be appreciated, of course, that in certain instances the spring biasing means I5 and outer portion 26 of the contact arm, inclusive of the hooks 26c and 26d, are made of a continuous piece of strip material or the like as by stamping, cutting and working to desired shape from a single piece of electrically conductive spring quality material, thereby achieving physical and electrical continuity.

A bracket 25 illustratively serves for mounting the insulator II as in upright position on a pole, line tower or transformer casing, and preferably in disposed at some point in the general vicinity of about half-way between the terminals I6 and I1 or their supports I8 andIS. The inner end of the bracket 25 preferably is of a form which connects to only one side of the transverse periphery of the insulator body, this connection, for example, being on the side directly opposite from those portions of the fuse cutout II) which are electrically conductive in the power transmission line. The bracket 25 illustratively is .a piece of rigid metal strip having one or more openings 25a therethrough, clear of the insulator body for receiving a screw, bolt, or the like to support the cutout It in useful position. The inner end of the strap or bar conveniently is affixed to the insulator II by being embedded therein or seated in a transverse opening in the side of the insulator body and cemented in. It will, of course, be understood that collars or bands of metal may under certain circumstances be employed for holding the bracket 25 or contact arms I2 and I3 to the insulator body, but this arrangement usually is not preferred, especially where the bracket is susceptible to easy connection with the line complete to ground as by birds roosting on the cutout Ill. By keeping the bracket 25 entirely to one side of the insulator II and disposing the contact arms I2 and I3 as well as their supports I8 and I9 entirely to the opposite side, so as to be remote from this bracket, danger of line to ground connection between the several elements is successfully reduced.

The specific form of insulator I I and the manner in which bracket 25 and supports I8 and I9 are mounted and arranged thereon form no part of this invention, but comprise the invention of James M. Wallace and Earl F. Beach, and are more particularly described and claimed in their copending application Serial No. 98,378, on Open Link Cutouts, filed June 10, 1949, and assigned to the same assignee of this invention.

The contact arms I2 and I3 illustratively have their respective longitudinal center lines in about the same plane as the longitudinal axis of the insulator II and are laterally strong by virtue of their effective widths in this direction and the form of the spring biasing means I5. For interconnecting these arms, the fuse link I4 preferably includes an opposed pair of electrical conductors 32 made, for example, of copper wire and provided at their outer ends with eyes 33. The inner ends of the electrical conductors 32 are spaced apart to form a gap, and located in this gap and connecting the conductors 32 is the fusible element 34 of relatively low melting point material. This fusible element 34 and the inner ends of conductors 32 preferably are enclosed within a tube 35 made, for example, of a weather-protective compound such as phenolic resin 29 lined with fiber 3|, or a like material which is capable of emitting an arc-suppressing gas when in proximity to an electric arc. Preferably a cap 30 is secured to the upper end of tube 35 and to the conductor 32'which passes through the cap. On the eyes 33 and located immediately adjacent to the inner sides thereof and joined to the conductors 32, are electrically conductive buttons or stops 33a for pressing against the outside surfaces of contact arms I2 and I3.

In use of the cutout I0, one of the opposed electrical conductors 32 of the fusible link I4 is set into the hook 260 or 26d of contact arm I2 with the corresponding stop 33a on that side of this arm which is remote from the arm I3. For this, a conventional switch stick is useful to handle an appropriate one of the eyes 33. With further use of the switch stick or tool, conductor 32 at the opposite end of the link I4 is set into either hook [3b or I30 of contact arm 13 with the corresponding stop 33a outside this arm. In the latter operation, the contact arm I2 is pulled against the bias of spring biasing means I5 toward the fixed arm I3.. Stops 33a once seated comprehend the contact arms I2 and I3, while thelink I4 is in tension under the bias of arm I2. The outer ends [3a and 26a of the contact arms in being inclined and substantially approaching each other, advantageously main tain the bottoms of the hooks I3?) and I30 toward the bottom of the opposed hooks 26c and 26d and thus make contact at more than one point. prevailing, the fuse cutout I6 serves to maintain current flow through the transmission line of which terminal I5 and the corresponding contact arm I2, fuse link I4, an contact arm I3 and Then with normal current conditions the corresponding terminal I1 comprise a part..

If, however, overload currents pass through the electrically conductive portions just named, the fusible element 54 in the link l4 ruptures or melts. When that occurs, contact arm I2 swings (clockwise in Fig. 1) with a snap under the force of the spring biasing means 15 thereof, quickly pulling apart the electrical conductors 32 of the link I4. Current flow thus no longer prevails across the cutout II), but can be restored and maintained if safe transmission limits exist, by

introducing another link I4 having a fusible component 34 of appropriate current rating.

Where, for example, the cutout Ii] is to be used for lending safety to a high voltage electrical transmission line, as is often the case, a considerable benefit is had by employing an insulator II having integral skirts Ila spaced along the length of the insulator body. These skirts tend to arrest corona discharge between the terminals I5 and H. The mounting bracket 25 conveniently is secured to the insulator H at a point intermediate theplurality of skirts Ila which then. also protect this element against discharge.

A somewhat modified form of spring biasing means I5 which is used in accordance with the present invention is represented in Fig. 5 of the accompanying drawing. In this particular embodiment of the spring means I5, a convolute portion is provided comprising two coils I5 and I5g respectively made by rolling or winding extension portions lEb and IE0 on opposite sides of main portion I 511, for example, by beginning with an electrically conductive metal blank'of the character described in connection with production of the single coil biasing unit represented in Fig. 3. It will be understood that the modified form of biasing means conveniently is disposed in the cutout II] in substantially the same manner as the single coil biasing means to serve in lieu of the latter.

Thus it will be seen that in this invention there is provided a tension fused cutout and apparatus for the same in which the various objects noted herein, together with many thoroughly practical advantages, are successfully achieved. 'Itwill be seen that the cutout is simple and is effectively biased in favor of snapping to open circuit position upon overload conditions being encountered. Also; it will be seen that the cutout can be readily produced and is easy to service.

Having described certain preferred embodiments of the invention in accordance with the patent statutes, it is desired that the invention be not limited to this particular construction, inasmuch as it will be obvious to persons skilled in the art that many modifications and changes may be made in this particular structure without departing from the' broad spirit and scope of this invention. Accordingly, it is desired that the invention be interpreted as broadly as possible and that it be limited only as required by the prior art.

I claim as my invention: 7

1. A fuse cutout comprising an electrical insulator, spaced electrically conductive contact arms extending from connection with the insulator and having their outer ends suited for receiving and holding a fuse link, one of said arms including an intermediately convolute electrically conductive flat spring member which is split at its inner end to provide spaced integral extension portions toward the insulator for mounting thereon, and a single integral main portion extending outward for urging the link receiving and holding end of the arm away from the corresponding'end of the other arm.

2. A fuse cutout comprising an electrical insulator, spaced electrically conductive contact arms extending from connection with the insulator and having their outer ends suited for receiving and holding a fuse link o'ne of said arms being substantially fixed in position and the other of said arms including a spring strip having spaced extension portions toward the insulator and a main portion coiled intoa spring between said extension portions and reaching outward for urging the link receiving and holding end of the arm away from the corresponding end of the substantially'fixed arm.

BJA fuse cutout comprising an electrical insulator, spaced electrically conductive contact arr'ns extending from connection with the insulator and having their outer ends suited for receiving and holding a fuse link, one of said arms being substantially fixed in position and the other of said arms including a conductive spring strip having spaced individually wound convolute extension portions toward the insulator and a main portion integral with and between the extension portions, said main portion being of less width than the gap between said extension portions and reaching outward for urging the link receiving and holding end of the arm away from the corresponding end of the substantially fixed arm.

4. A fuse cutout comprising an elongated electrical insulator, a bracket connected with an intermediate portion of said insulator for supporting the insulator body, spaced electrically conductive contact arms extending transversely outward from connection with the opposite end portions of the insulator and suited for receiving and holding a fuse link at their outer ends, one of said arms being of flat strip material comprising an inner portion formed as an intermediately convolute spring strip which is split at its inner end to provide spaced extension portions toward the corresponding insulator end for mounting thereon, and a single main portion extending outward for urging the outer link receiving and holding end of the arm away from the corresponding end of the other arm.

5. A fuse cutout comprising an elongated electrical insulator, spaced electrically conductive contact arms extending transversely outward from connection with the opposite end portions of the insulator and having their outer ends suited for receiving and holding a fuse link, one of said arms being substantially fixed in position and the other of said arms being substantially flat in transverse cross section with the longer sides of the cross section substantially lateral to the intended position of the fuse link, for rigidity in this direction, and said substantially flat arm including a spring strip having spaced extension portions toward the corresponding insulator end and a main portion coiled into a spring between said extension portions and reaching outward for urging the link receiving and holding end of the arm away from the corresponding end of the substantially fixed arm.

6. A fuse cutout comprising an elongated electrical insulator, spaced electrically conductive contact arms extending transversely outward from connection with the opposite end portions of the insulator and having their outer ends suited for receiving and holding a fuse link, one of said arms being substantially fixed in position and the other of said arms being substantially flat in transverse cross section with the longer sides of the cross section substantially lateral to the intended position of the fuse link, for rigidity in this direction, and said substantially flat arm including a conductive spring strip having spaced individually wound convolute extension portions toward the corresponding insulator end and a main portion integral therewith and between the extension portions, said main portion being of less width than the gap between said extension portions and reaching outward for urging the link receiving and holding end of the arm away from the corresponding end of the substantially fixed arm.

7. A contact arm for. the fuse link of a tensioned fuse cutout, said arm comprising electrically conductive spring strip means having a main portion, and integral extension portions reaching from said main portion and forming a gap between each other greater than the width of the latter, and said spring strip means being convolute intermediate the length thereof.

8. A contact arm for the fuse link of a tension fuse cutout, said arm comprising an electrically conductive spring strip having a main portion, and extension portions reaching from said main portion and forming a ap between each other greater than the width of the latter, and said main portion being wound between said extension legs to provide a coil.

9. A contact arm for the fuse link of a tensioned fuse cutout, said arm comprising an electrically conductive spring strip having a main portion, and integral extension portions reaching from said main portion and forming a gap between each other greater than the width of the latter, and said extension portions being individually wound beside the main portion to provide coils.

ANDREW W. EDWARDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 819,608 Sherwood May 1, 1906 2,215,321 Cooley Sept. 17, 1940 2,272,370 Fox Feb. 10, 1942 2,304,250 Fox Dec. 8, 1942 2,347,851 Steinmayer et a1 May 2, 1944

Images