US1771735A - Expulsion-fuse cut-out - Google Patents

Description

July 29, 1930. I. SJ RAYMER EXPULSION FUSE CUT-OUT Filed Feb. 4, 1925 2 Sheets-Sheet 2 4 ATTORNEY Patented July 29, 1930 IRA s. RAYMEJK, or BEAVER, PENNSYLVANIA nxPULsIoN-rUsn CUT-OUT Application filed February 4, 1925. Serial No. 6,796. g

This invention relates to expulsion fuse cut-outs and more part1cularly to fuse cutouts for use in connection with high-tensioncircuits at exposed locations. In connecting transformers or other electrical equipment to high-tension transmission lines or other high voltage sources, it is desirable to provide a cut-out or circuit breakin means which will break the circuit upon an excessive flow of current and will.

open up a long gap atsuch break so as to ex tinguish the are which follows the interruption of a high voltage circuit.

\Viththe above and other considerations in is mind, it is an object of the present invention to provide a cut-out device of the expulsion fuse type, which. utilizes an explosive com.- pound ignited by an excessive flow of current and acting to rupture the circuit, to extin 2e guish the arc and to releasespring means or the like which act to open up and'to maintain a wide gap in the circuit. It is another object of for use on poles or other elevated or remote structures which will give such an .indica tion of the condition of the fuse by the rela live position of its parts as will enable the operator to easily ascertain from a int on to the ground whether or not the fuse as been blown.

It is a further object of this invention to provide an expulsion fuse cut-out which may be used as a quick-acting disconnecting 3.) switch.

It is a still further object of this invention to provide a fuse cut-out having a cheap and compact replacement unit which may be readily removed and inserted.

It is another object of this invention to provide a combined expulsion fuse, disconnecting switch and reactance coil in a single compact unit. I

It is another object of this invention to provide an, expulsion fuse structure including a sealed chamber for housing a fuse wire and protecting it against injury.

Other objects and advantageous features of the present invention will become apparcut as the description thereof progresses.

this invention to provide an expulsion fuse cut-out suitable In the drawings, Fig. 1 represents a side elevation of the expulsion fuse cut-out comprising the presentinvention, together with one form of mounting therefor;v

Fig. 2 is a sectional end view of the spring fuse clips taken along the section line 22 of Fig.1;, g

' Fig. 3 isa fragmentary sectional to view of the contact structure taken along t e section line 3-3 of Fig. 1; I I i I Fig. 4 is a perspective View of a portionof oneof the fuse carrying bars; A

F ig. 5 is a side elevation of a modified form of a fuse cut-outcomprising a combined fuse, disconnecting switch and choke coil, together witha mounting therefor; i 1

Fig. 6 is an end view of the structure shown in'Fig.5; I, i

Fig. 7 is a sectional view of a portion of the fuse carrying structure, taken along the line 7r-7 of Fig. 6 and viewed in the direction of the arrows; Fig. 8 is a side elevation of the fuse carrying structure on an enlarged scale; and

Fig. 9 is a sectional View of the structure shown in Fig. 8, taken along the line 9-9 and viewed in the direction of the arrows. Referring to Fig. 1, the fuse structure is supported on two insulators 1 and 2, of the well known petticoat pin type, which are carried by a U-shaped supporting bar 3, these insulators beingcomposed of porcelain, glass, or any other suitablematerial. As the structures carried by these insulators 1 and 2, are substantiallyidentical, a detailed description of the apparatus carried on one of them, only will be given, the corresponding parts carried by the other insulator being designated by like reference characters. The ,bar 3 may be secured to any suitably supported structure, such as the bracket or rod 4,, by means of the bolts 5 and 6. .A circular metallic cap .7, is cemented over the upper portion of the insulator 1. This cap is provided with .a vertical lug or plate 9 which is preferably made integral'with the cap and extends diametrically across its upper surface as shown.

1 Fuse holding clips are secured to the lug 9 by means of the bolts 11. These clips in the specific form shown consist of three vertically arranged clip members 12, 13 and 14, which are preferably stamped from resilient sheet copper. The clip members 12, 13 and 14 are flared outwardly at their upper ends as shown at 15 and 16 in Fig. 2, in order to facilitate the insertion of the fuse blades. The clip member 12 is provided with an in wardly extending catch or hook 17. which is formed by bending a portion of the clip near its upper edge at right angles to the body of the clip as clearly shown in Fig. 3, the edge of this catch being beveled as shown in Fig. 2, so that said catch tapers in width.

The lug 9 also carries a fuse separating or expulsion spring 18 which acts to throw the fuse end as hereinafter described. This spring 18 is made of heavy spring steel wire in the form of a loop 19 which passes around the fuse holding clips 12-, 13 and 14 as shown in Figs. 1 and 3; the ends of the loop being formed into coiled springs 20 carried on the pin 21, which passes through the lug 9. A U-shaped retaining clip 22 is carried on the pin 21 as shown, and serves as a stop for the ends of the coiled spring 20.

The fuse structure proper consists of two members which are adapted to be widely separated when the fuse acts to open the circuit. Each member consists of a metallic end piece E and a fuse carrying bar 24. The end pieces are composed of copper'or some other suitable conducting material and are provided with blades 25 which are adapted to be firmly retained by the clip members 12, 13 and 14, as

shown. Each blade 25 is provided with an opening 26 to facilitate the removal of the fuse structure, as hereinafter described. A small notch 42 is provided in the upper edge of the blades 25 and cooperates with the catch 17 to prevent the blades from being forced out of the clips 12, 13 and 14 when the fuse is blown. A fiat strip 27, integral with each end piece E, extends upwardly at one end of each fuse blade 25, and is bent back in a horizontal plane over the blade and the clips 12, 13 and 14 as shown. These strips '27 act as stops, as hereinafter described, and also act as shields to prevent the entrance of dirt or other foreign matter between the clips. Each end piece is provided with two downwardly extending legs 28 and 29 which are connected by a rod 30, against which the loop 19 of the spring 18 is arranged to hear when the fuse structure is in place. Each fuse carrying bar 24 is clamped to an end piece E by means of an angle piece 32 and screws 33, the angle piece 32 being secured to the end piece by means of the rivets 34. The fuse carrying bars 24 are composed of any suitable insulating material, preferably of a frangible and moisture-proof naturesuch as a phenolic condensation product. A small cup-like depression or cut out portion 35 is provided near the free end of each of the bars 24, and a groove 8 is provided leading from this depresion to the other end of the bar as clearly shown in Fig. 4.

Suitable fuse wires 36 (see Fig. 4) are carried in the grooves 8, these grooves being subsequently filled with a suitable moisture proof insulating cement. The fuse Wires 36 are so constructed as to have a point of initial fusibility directly over the depressions 35 in the bars 24. This feature may be accomplished by using copper wire in the grooves 8 and a fusible wire across the depressions 35, or any other suitable means may be provided to accomplish this result. In the specific embodiment shown, a double fuse wire is provided in the grooves 8 and a single fuse wire is used at a point directly over the depre sions 35. The bars 24 overlap at their free ends in such a manner that the depressions 35 coincide to form a closed chamber. 'hen the fuse structure is assembled, the depression's 35 are filled with an explosive substance such as gun powder which will ignite and explode with considerable force at a suitable temperature. The engaging surface of the plates 24 are covered with a suitable moisture-proof insulating cement and are clamped or pressed together until the cementing substance has hardened. From the above description, it is clear that the explosive substance in the chamber together with the fuse wires is carried in a moisture-proof enclosure and is so suitably protected for use at points exposed to the weather.

A choke coil is preferably provided in connection with the fuse to protect it against surges of current due to lightning or other causes. This coil may be of any suitable construction, but in the embodiment shown consists of a vertically arranged plate 37 of insulating material carrying a coil 38 of heavy wire, preferably copper, which is wound through rows of holes 39 and 40, in the plate 37. The choke coil is secured to the lug 9 by means of an angle bar 41 of conducting material, to which one terminal of the coil electrically connected as clearly shown.

As pointed out above, the portion of the fuse wire 36 which extends through the depression 35 is of such a composition and cross section that an excessive amount of current heats it to a temperature at which it melts and separates. As the fuse wire separates and opens the circuit, an arc is drawn which ignites the explosive substance contained in the'chamber, and as this explosive is closely confined, it will explode with considerable violence, rupturing the bars 24. This rupture of the bars ordinarily occurs at the depressions 35 where the cross section of the bars is reduced and where the force of the explosion is greatest. If desired, the explosive substance may be made to ignite at temperatures below the melting point of the fuse, thus utilizing the force of the explosion to break the circuit. When ruptured by the explosion, the ends of the bars 24 together with the end piecesE arethrown upwardly and apart by the springs 18, thus widely separating the ruptured ends of the fuse wires 36, and placing the bars 24 in such a position that the condition of the fuse can be readily determined. This indication of the condition of the fuse is of considerable importance as fuses of this type are ordinarily mounted on poles or other elevated structures and the marked change in the appearance ofthe device when blown makes its condition readily apparent to the operator from the ground or other remote point. As the blades are thrown upwardly by the springs 18, the notches 42 in the blades strike the catches 17 on the clips 12, and this engagement prevents the blades from being forced out of the clips, and also acts as a fulcrum about which the blades are swung. As the blades 25 are swung upwardly, the ends of the strips 27 come into engagement with the clips 22,'and so act as stops to limit the movement of the blades and their associated bars 24.

When the fuse cutout is designed for large currents, a heavy fuse wire is used, and in this case theexplosive substance may beomitted from the chamber, the arc and gases formed by the burning of the fuse wire being sufiicient to rupture the blades and open the circuit. a

After the fuse has been blown, the blade members 25 have been acted on by springs 19 to rotate them substantially 90 to thus free the notches 42 from the projections 17, and thus they may be removed by inserting a hook or other suitable tool through the openings above the rod-s and drawingthe blades 25 outwardly from between theclips. The ends of the ruptured bars 24, are now removed from the end pieces E, and a replacement unit, comprising two bars 24 cemented together and provided with fuse wires being properly cleaned and clamped securely in contact with the end pieces by means of the screws 33. The renewed fuse structure may now be inserted by forcing the blades 25 into the clip members and under the catch 17 It is sometimes found necessary to open the circuit through the fuse in order to make replacements or repairs. This may be readily accomplished by inserting a hook or other tool through the opening 26 in one of the blades 25 and releasing the corresponding catch 17. The springs 18 will thenthrow the released blade 25 out of its clips 12, 13 and 14, and the released end of the fuse structure will be thrown outwardly, the other blade being retained in the clips by its catch 17 and notch 42, and the movement of the fuse structure being limited by the engagement of the end of the strip 27 with the clip 22. The fuse structure will be positively held in this open position by the spring18 so that it cannot be swung closed by wind pressure or vibration. In this manner, it is clear that the fuse structure of the present invention also constitutes a ositive and quick-acting disconnecting switch or cut-out.

Referring now more particularly to Figs. 5 through 9, a modified form of a fuse cutout has been shown. In this modification, the fuse structure is supported by two petticoat pin type insulators 44-and'45 which-are secured to a suitable supporting bar 46 by the bolts 47. The insulators 44 and carry two downwardly extending metallic legs 48 and 49 respectively, the leg 48 carrying a conducting metallic plate 50, and the leg 49 carrying a conducting plate 51, secured thereto by suitable bolts 52, as shown. A downwardly extending clip member 53, having a bifurcated end, is secured tothe plate 5O by the screw 54, and carries a blade member 55, pivotally secured thereto by the bolt 56 as shown.

The switch blade portion of the modified cut-out includes a choke coil, constructed in the same manner as the choke coil shown in Fig. 1, having a vertically arranged plate of insulating material 57 provided with two parallel rows of holes 58 through which the wire 59 of the choke coil is wound. Blademembers and 60 arebol ted to either end of the insulated plate 57, and are electrically connected to the opposite ends of the choke coil by the connectors 61 and 62 respectively as shown. In order to maintain a good electrical connection between the plate 50 and the blade 55, a flexible cable 63 is connected be-- tween these members,forming a parallel electrical path around the pivotal connection between the clip member 53 and the blade member 55. I l

The fuse structure in the modification shown in Figs. 5 through 9 is secured between the plate 51 and the blade 60. An inverted U-shaped metallic member 64,11avinginwardly projecting edges 65'. is secured to theplate 51 by the screw bolts 66.,the heads of these bolts being countersunk in the member 64 as in its lower face as most clearly shown in Figs. a

8 and 9. The ends of theblock 67 are tapered and rounded as shown, and are provided with vertically extending holes, 87. i A lower block 69 of insulating materiahhaving a reduced upper portion, is secured to the lower face of the block 67 by means of a suitable cement or glue, preferably of a waterproof nature, and covers the depression 68 in the block 67, forming a closed chamber between the two blocks. The block69 is provided with two metallic contact plates 7 O, securedto opposite sides of the reduced upper portionthereof by the rivets 71, these plates 70 being adapted to engage depressions 72 in the in-turnededges 65 of the member 64 when the block67 is held in the member 64 as shown in Figs. 5 and 6. A metallic plate 73 and switch blade clips 7 4 are secured to the lower face of the block 69 by the bolts 75 and 76. As clearly shown in Fig. 9, the bolt 75 is entirely enclosed by the block 69 while the bolt 76 passes through to the upper face thereof and is provided with a terminal screw 77 in its upper end, this terminal screw lying within the depression 68 when the blocks 69 and 67 are cemented together. A second terminal screw 78 is provided in the upper face of the block 69, and engages one of the rivets 71 connected to the contact plates 70. A fuse wire 79 is connected between the terminal screws 77 and 78 when the fuse structure is assembled, the depression 68 being preferably filled with an explosive substance and the blocks 69 and 67 being then cemented together. It is clear that when the fuse structure is assembled, and the blade 60 engages the clips 74, the fuse wire 79 is included in an electrical circuit between the blade 60 and the plate 51, this circuit including the bolt 76, the screw 78, the rivet 71, the plates and the U-shaped member 64.

An extension 80 is provided on the plate 73 and has two downwardly extending legs 81, provided with outwardly turned extremities 82 having slots 83 therein as shown. The legs 81 are provided with openings which carry a spring retaining loop or latch 8st which is adapted to pass over the end of the blade 60 and to retain this blade between the clips 7 4. The edges of the extremities 82 may be beveled or rounded to permit the latch to be pulled outwardly to release the blade 60. A loop of spring wire '85 is coiled about the ends of the bolt 56; its extreme ends passing over the blade member 55 and the clip member 53; and biasing the blade member to turn in a clockwise direction about the bolt 56 thereby tending to separate the blocks 69 and 67 andto swing choke coil structure downward when the fuse is blown. In certain cases, the spring 85 may be omitted, the blocks 69 and 67 being separated by gravity when the fuse is blown.

The operation of the modification shown in Figs. 5 through 9 is similar to that of the modification shown in Figs. 1 through -i. Vhen an excessive current flows, the fuse wire 79 melts and separates, igniting the explosive substance contained in the depression 68. rupturing the cement and blowing the blocks 67 and 69 violently apart. The spring 85 acts to swing the block 69 together with the clips 74, the blade 60 and. the choke coil structure rapidly downward and away from the member 64, this entire structure being pivoted about the bolt 56 passing through the blade 55. As the blocks 67 and 69 are separated, the contact plates 70 disengage the edges of the U-shaped member 64, thus breaking the circuit if it has not already been broken by the burning of the fuse wire. If the currents used are comparatively large, the explosive substance may be omitted, the gases formed by the burning of the fuse wire being sufficient to separate the blocks 67 and 69. After the fuse has been blown and the circuitis again in condition to be closed, the block 67 is pulled out of the member 6% by means of a hook or other tool inserted in one of the holes 87, and anew unit, comprising two blocks 67 and 69, cemented together and provided with a fuse wire and the explosive substance, and carrying the clips 74, is pressed into the member 64. This new fuse structure is held in the proper relation to the ren'iainder of the structure by means of the engagement of the contact plates 70 with the depressions 72 in the edges of the member 64. The block 69 carrying the burned out fuse wire, together with the clips 74; and the latch 84 is removed from the blade 60, and the blade is then swung up by means of a hook or other suitable tool inserted in the opening 86 of the blade 60, the latch 84 of the new fuse and clip structure being dropped over the end of the blade 60 to hold it in place. The spring 85 is sprung on to the extension 55, and the replaced fuse structure is then in condition for operation.

It is obvious that by swinging the latch 84. away from the blade 60 and inserting a hook or other tool in the opening 86 of the blade 60, this blade, together with the choke coil structure, may be swung downward and out of engagement with the clips 74, thus opening the circuit through the device. In this manner, the device may be used as a disconnecting switch.

It is seen that a structure has been provided which acts as a combind expulsion fuse, a dis connecting switch and a choke coil, the arrangement being extremely simple and compact and the fuse unit being inexpensive and readily replaced.

Vhen comparatively heavy currents are to be carried by the fuse structure, it is often desirable to invert the arrangement shown in Fig. 5 mounting the combined choke coil, dis connecting switch and fusestructure above the insulators and securing the lower ends of the insulator pins to a support. hen arranged in this manner, the are formed by the rupture of the circuit would be blown upward in a manner similar to the operation of the well known horn gap, and would be extinguished without damaging the cut-out structure. In such an inverted arrangement, the spring 85 would have to be made strong enough to swing the entire choke coil and fuse structure upward and the latch 84 would be provided with some suitable spring retaining means. This is such an obvious n'iodification of the forms shown in the drawings, that specific illustration of the same is deemed unnecessary.

As the present invention has been disclosed and described in connection with a rather specific form of fuse structure, it should be clearly understood that the invention is not limited in its scope I to the structure shown, and that many changes and variations of structure might be made without departing from the spirit of the invention as defined by the appended claims.

What it is desired to secure by Letters Patcut is '1. In a fuse cut-out, a wire having a fusible portion, a member having an enclosed chamber surrounding said fusible portion, said member comprising an element of insulating material having a receiving chamber therein, and an explosive substance Within said chamber to cause a rupture of said member and a separation of said wire when said fusible portion reaches a predetermined temperature and elastic means for moving apart the separated parts.

2. In an electric cut-out, acurrent carrying means, an explosive substance for separating said means at a predetermined temperature, and mechanical means for moving apart the separate parts of said element.

3. In combination, a choke coil, a disconnecting switch and an expulsion fuse suspended between two supports, said fuse acting on overload to move said supports apart to thus separate conducting members and open a circuit.

4. In combination, a supporting structure comprising two supports carrying c0nducting members, and means electrically connected between said members including a choke coil and an expulsion fuse, said fuse being adapted to move the supports apart to separate said conducting members.

5. In a fuse cut-out, an insulating support, a choke coil pivotally secured to said support, a switch blade rigidly secured to said choke coil, clip means for engaging said switch blade and a separable connection for securing said clip means to a second insulating support comprising two members, one of insulating material, carrying a fuse Wire therebetween.

6. In a fuse cutout, two insulating supports, a choke coil having one end thereof electrically connected to and pivotally supported by one of said supports, and means for separably connecting the other end of said choke coil to the other of said supports comprising two separable members, one of insulating material, carrying a fuse Wire and an explosive substance therebetween.

7. In a fuse cut-out, a separable means for securing a switch blade to a terminal comprising, a first member of insulating material secured to said terminal and having a depression, a second member of insulating material connected to said first member, a fuse wire carried by said members and lying in the depression in saidfirst block, blade retaining means secured to the exposed face of said second member and means for electrically connecting said fuse wire in a circuit between said blade retaining means and said terminal.

8. In a fuse cut-out, a switch structure comprising a choke coil connected in series between two blades, a pivotal support for one of said blades, a clip for retaining the other of said blades and a fuse structure for securing said clip to an insulating terminal plate comprising two separable blocks carryin g a fuse wire therebetween, and a normally tensioned spring acting to separate said blocks when said fuse Wire is blown.

In testimony whereof I afiix my signature.

' IRA S. RAYMER.

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