US2629794A

US2629794A - Fused drop-out cutout

Info

Publication number: US2629794A
Application number: US203380A
Authority: US
Inventors: David C Hubbard; William L Hollander
Original assignee: AB Chance Co
Current assignee: AB Chance Co
Priority date: 1948-07-26
Filing date: 1950-12-29
Publication date: 1953-02-24
Anticipated expiration: 1970-02-24

Description

1953 D. c. HUBBARD EI'AL FUSED DRO'P"OUT CUTOUT 2 SHEETS-SHEET 1 Original Filed July 26, 1948 Feb. 24, 1953 D. c. HUBBARD ET AL 2,629,794

FUSED DROP-OUT CUTOUT Original Filed July 26, 1948 2 SHEETS-SHEET 2 Invenfor fie/ 15 Patented Feb. 24, 1953 FUSED DROP-OUT CUTOUT David C. Hubbard and William L. Hollander, Centralia, M0., assignors to A. B. Chance Company, Centralia, Mo., a corporation of Missouri Original application July 26, 1948, Serial No. 40,756, now Patent No. 2,537,348, dated January 9, 1951. Divided and this application December 29, 1950, Serial No. 203,380

12 Claims. 1

The present invention relates to fused dropout cut-outs, and is particularly concerned with automatic fuse devices of the type adapted to be used upon transmission lines for interrupting the flow of current when the current exceeds a pre determined amount, the interruption being accompanied by the melting of the fuse and the expulsion of the parts of the fuse, accompanied by the automatic mechanical opening of the circuits, after the circuit is broken, to assure the permanent breaking of the circuit until it is manually closed, and to give an indication of the condition of the circuit.

The present application is a division of our prior application, Ser. No. 40,756, filed July 26, 1948, for fused drop-out cut-outs, Patent No. 2,537,348, granted January 9, 1951.

One of the objects of the invention is the provision of an improved drop-out type fuse cut-out adapted to utilize the standard universal fuse links and provided with a fuse tube, which is closed at the top and open at the bottom, and so constructed that the lower contact of the fuse tube is ejected from the bottom contact of the circuit, so that the fuse tube will hang with its opening downward before and after operation, thus protecting the fiber liner of the fuse tube from all adverse weather conditions.

Another object of the invention is the provision of an improved fuse drop-out cut-out in which the actual parting of the lower contacts upon rupture of the fuse link is delayed until after the arc has been extinguished inside the fuse tube.

Another object is the provision of an improved device of the class described in which the ejector arm travels over a predetermined are before unlatching the lower contact, so that the actual mechanical opening of the circuit will be delayed until the arc has been definitely extinguished within the fuse tube.

Another object is the provision of an improved device of the class described in which there is a wiping contact between the contacts on the fuse tube and those on the support so that the contacts may be kept in good condition and so that the wiping contact at the lower contact of the fuse tube may be used during the unlatching of the fuse tube to assist in delaying the mechanical opening of the circuit until the arc has been extinguished within the tube.

A further object of the invention is the provision of an improved drop-out fuse construction in which the jet action from the opening at the lower end of the fuse tube reacts with the up- 2 per trunnion to produce a torque that tends to swing the lower end of the fuse tube inward toward its contact to hold the lower contact in engaged position during the blast of the are so as to delay the mechanical opening until the arc has been extinguished.

Another object of the invention is the provision of an improved construction for devices of the class described in the form of the resilient spring supported contacts, and the provision of stops which protect the springs during jet action. to prevent the straining of the springs and to cause the forces to react in such manner that the top trunnion of the fuse tube is also held in closed position during the violent jet action from the lower end of the fuse tube.

Another object of the invention is the provision of an improved ejector construction adapted to pull the fuse link from the fuse quickly at all times, even though the rupturing currents are too light to generate sufficient gases within the fiber tube to eject the link rapidly, thus assuring the extinguishment of the arc in a minimum time.

Another object of the invention is the provision of an improved fuse tube drop-out cut-out, the parts of which are protected from the weather at all times, and which is also adapted to be operated in a conventional way as a disconnect by permitting the manual disengagement of the upper contacts by merely pulling outward on this end of the tube, leaving the tube supported by its lower contacts, and indicating that it has been manually operated as a disconnect.

Another object of the invention is the provision of an improved fuse construction which is adapted to be re-fused and operated in accordance with conventional procedure so that the operators will already be familiar with the mode of handling the device.

Another object of the invention is the provision of an improved fuse drop-out cut-out which is trip free, even during the manual closing of the circuit, so that when the fuse tube unit is being connected with its contacts, the operator cannot force the closing of the circuit during the existence of an overload; but while the operator is swinging the upper contact into closed position and holding it, the device may nevertheless open at the bottom contact automatically, if a short circuit exists at that time.

Another object of the invention is the provision of an improved fuse tube unit which is provided with means for guiding and diverting the molten elements and the major force of the blast which takes place on fusing, away from the operator, so as to provide limited but efiective protection for the operator, and particularly for his face.

Another object is the provision of an improved device of the class described having a mechanism that is unaffected by accumulations of ice, and which. is adequately protected from such accumulations as may occur.

Another object of the invention is the provision of a device of the class described which gives a visual indication, in the open position whether the device has been operated automatically, indicating the existence of a fault, or whether the device has been opened manually, indicating the purposeful de energizing of the circuit for repairs or other reasons.

Another object is the provision of an improved contact structure which is self-aligning with relation to the trunnions on the fuse tube unit, and the provision of stops and buffers to arrest the reaction that is due to the jet action, and to prevent overstressing the contact springs.

Another object is the provision of an improved fuse tube unit and support therefore which is so constructed. "that the forcible closing of the contacts, by slamming the fuse tube into position, tends to force the ejector arm against the bottom of the fuse tube, rather than to the arm to place additional tension on the fuse link element, thus eliminating the shocks that are imparted to the fragile fuse link in the devices of the prior art.

Another object of the invention is the provision of an improved ejector m chanism for the fuse leader, in which the cable is so arranged that it does not slide over the end of the ejector lever as the lever moves, thus reducing or substantially eliminating; the friction which would be caused by such a sliding action, and which would resist the ejector lever operation.

Another object is thep revision of improved contact arrangements by means of which the contact fixtures on the fuse tube unit are resiliently urged into engagement with. the fixed contact arms, and by means of which the contacts are self-aligning with respect to the trunnions on the 'fuse tube unit, and by means of which thelongitudinal pressure on the fuse tube, which sometimes causes bending, after a long period of time, is substantially eliminated.

Other objects and advantages will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to two sheets of drawings accompanying this specification,

Fig. 1 is a fragmentary side elevational view in partial section, showing a fused drop-out cutout embodying the invention;

Fig, 2 is a fragmentary side elevational view,

howing the position of the parts of the lower Y end of the fuse tube unit after the fuse has blown;

Fig. 3 is a fragmentary sectional. view on the plane 'of the line 3-3 of Fig. 1, showing electrical connector by means of which the lower contact arm is connected to a Wire cable or other conductor; and

Fig. 4 is a fragmentary sectional View, taken on the plane of the line -ii of Fig. '2, looking in the direction of the arrows.

Referring to Fig. 1, it) indicates in its entirety the fuse drop-out cut-out assembly, which preferably includes a supporting structure I i and fuse tube unit l2 carried thereby. The supporting structure H may be embodied. in the single insulater type shown in Fig. l, or it may be carried by two insulators in the manner shown in the prior application of David C. Hubbard, Ser. No. 11,076, filed February 26, 1948, Fuse Drop-Out Cut-Outs, now U. S. Patent 'No. 2,584,586 granted February 5, 1952.

The single insulator type of Fig. 1 has a porcelain insulator !3, which is formed with a multiplicity of peripherally extending skirts 14 separated by grooves I5; and the insulator prefer- .ably has a reduced cylindrical portion l6 adjacent at its middle, and additional reduced cylindrical portions H at each end. The middle cylindrical portion I S of the insulator is surrounded by a metal/band IS, the ends of which are provided with two laterally projecting attaching flange-s,

having a screw bolt 22 passing through them and clamping them together.

The clamping band [9 is a part of the structure used for supporting insulator I3 from a cross arm or other support substantially as disclosed in our prior application :of the same title, filed March 8, 1948, Ser. No, 13,704, new U. .3. Patent No. 2,581,954 granted January-8,.1952.

Thus the insulator I3 is adapted to be supported from a horizontal cross arm in a tilted position so that the fuse tube unit 12 will extend diagonally upward and away from the cross arm in such manner that whenever thefuse tube unit hangs only from the upper contact arms it hangs in a vertical position by gravity. By reason of this position of the insulator and fuse tube unit the fuse tube unit is so supported that it may pivot upon either the upper trunnions or the lower trunnions by gravity to a position which it will retain by gravity.

The reduced cylindrical portions 51 .at each end of the insulator 13 are bordered "by one of the insulator skirts on one sideand a radially projecting r-ib on the other side, forming a groove for receiving the clamping bands 36,, which carry the upper and lower

contact supporting arms

38, 39, substantially as described in our said U. S. Patent No. 2,581,954.

The contact supporting arms consist of a pair of laterally extending flanges orstra-ps extending from the clamping bands 35 and adapted to be secured to contact fittings by being provided with aligned. bores for the screw bolts 43, "44 below and I20, I21 above.

The lower contact fitting 46 comprises an elongated conductive metal casting provided with a. flat attaching flange 45, which may be received between the flanges of the arm 39 on .hand .36 and secured by

screw bolts

43, 44. Lower contact fixture 46 has ,a hood or partial housing 4'! for supporting the lower contact trunnions 63 and for enclosing the ejector and contact mechanism,

and for protecting the lower mechanism from rain, snow, and other adverse weather conditions.

The lower fixture 46 may consist of a cast metal member provided with a relatively flat attaching flange and with an aperture 48 for passing a connector bolt 49, which is apertured below its elongated head 50 for receiving a conductor that is clamped in a groove 5| by a nut on the shank of the bolt which pull the head against the conductor.

A similar connector 49 is carried by an upwardly projecting flange 52 carried .by the upper contact fixture 53. The hood 4'! has parallel side walls 54, a curved top wall 55, and a flat rear wall 51 (Fig. 1), leaving the bottom open between the side walls 54, when the fixture is installed properly, as in Fig. 1.

The side walls 54 of the hood 4! are provided with the laterally inwardly projecting integral cylindrical trunnions 63, which project inwardly from the side walls in alignment with each other and toward each other, but terminate short of each other to permit the ejector lever of the tube unit I2 to move between these trunnions 63.

The inner ends 99 of the trunnions 63 are spaced from each other sufiiciently to pass the relatively flat flange and reinforcing portions of the ejector arm 68, which is pivotally mounted on the tube unit I2.

The hood 4'! supports a leaf spring 69, which extends along the inside of its top wall 56, and which is initially spaced from the top wall, being tensioned when bent upward, as shown in Fig. 1. This leaf spring 69 passes through an aperture in the rear wall 51, and is secured to a horizontal flange I by means of a rivet II. Spring 69 urges the contact portions of the fuse tube unit I2 resiliently against the trunnions 63.

The fuse tube unit I2 comprises an insulating tube I2, preferably having an outer portion 13, which is adapted to resist exposure to weather, and an inner portion M, which is adapted to re sist burning by the heat generated in the melting of the fuse, these two portions being integrally cemented together to form a single tube.

At its lower end the fuse tube I2 supports the contact fixture I5, which has an upwardly open tubular member I9 for receiving th lower end of the fuse tube. The fuse tube is fixedly secured in the ferrule I6 of the lower fixture 75 by a pair of screw bolts 11 threaded into bores in the ferrule and penetrating only partly into the thick tube I3 so that the inner ends of the bolts I1 are covered by the inner tube I4.

The fuse tube terminates at I8, inside the blast chute I9, and is open at its lower end, where it is constantly protected from the weather by hanging downward, either in the position of Fig. l or, after blowing of the fuse, in the vertical position of Fig. 2. The lower fixture I5 support the integral blast chute 19, which has a pair of parallel side walls 80, a top wall 8! flush with the end 18 of the tube, and a diagonally extending rear wall 82, which extends over toward the center of the tube "I2, and is adapted to deflect the gases downwardly and toward the right, away from the face of the operator.

The side walls 80 of the blast chute 19 each support an outwardly projecting cylindrical stud 83, which is adapted to provide the pivotal support and point of attachment of a fuse leader guard adapted to receive and hold the cable of the fuse when the fuse is blown. The fuse leader guard forms no part of the present invention and may be substantially as shown. in the prior application of David C. Hubbard, Ser. No. 792.8049, filed December 19, 1947, now U. S. Patent No. 2,461,898 granted February 15, 1949.

The lower fixture I5 is formed with an integral ring 84 located on its upper side, in Fig. 1, for reception of the laterally projecting operating pin of a disconnect stick, upon which the fuse unit I2 is hung when it is to be installed. Lower fixture I5 also has an integral substantially cylindrical body portion 85 below the ring 84 and provided with a cylindrical bore 86 for receiving an ejector spring 81.

The ejector spring comprises a helical coil spring reacting at its right end on the end of the bore 86 and engaging at its left end the washer 88 of an ejector strut 89. Ejector strut comprises a stiff strip of sheet metal, having a I reduced end 90, which passes through an aperture 6 in the insulating washer 88, and having at its other end 9I a V-grooveor fork for engaging on both sides of the ejector lever 68 at its right edge. Thus the ejector spring 81 urges the ejector lever 68 toward the left in Fig. 1 by means of the strut 89.

The upper wall of the cylindrical formation 85 is extended toward the left to form a part of a roof 92, which curve upwardly under the top wall 56 of the hood to make sure that the hood overlaps and drains on the lower fixture I5 at a point where the water will not run into the mechanism.

Referring to Fig. 2, the laterally projecting portion 93 of the lower fixture I5 is provided with a rectangular slot 94 open toward the left, and adapted to receive the pivot flange 95 of the ejector lever 88, which is pivoted on the rivet 96. The rivet 9B, which forms the pivot for the ejector lever, also has a laterally projecting cylindrical portion 91 (Fig. l), about which the cable leader 99 may be wrapped when the fuse is installed in the fuse unit I2.

Lower contact fixture 15 also has a laterally projecting cylindrical threaded stud 99 provided with a knurled thumb nut I00, which is adapted to clamp the end of the fuse leader 98 after it has been passed about the threaded stud 99.

The present fuse units I2 are adapted to receive standard fuses, each of which has a circular button at the top adapted to be clamped against an end surface on the upper fixture II by means of the internally threaded cap I02. The fusible portion of the fuse is located in the upper end of the tube I2, and i connected to the stranded copper wire leader cable wire 98, which extends downwardly out of the lower end of the tube I2 and out of the blast chute I9.

Fuse leader 98 passes around the end I03 of the ejector lever 68, and is located in a groove I04 in the bottom or end of ejector lever 68. From the groove I84 the leader 98 passes about the stud 98; and its end is passed about the stud 99 and clamped by the thumb nut I 00. When the fuse leader i so installed, the ejector lever 68 is tensioned; that is, it is moved from the position of Fig. 2 to that of Fig. 1, compressing the spring 81 and causing the fuse ejector lever 68 to place a tension on the fuse leader 98.

The ejector lever 58 is pivoted in the slot 94 between the parallel portions I95 of the lower fixture I5; and ejector lever 98 has a relatively flat body flange I96, which is relatively thin, but \lvgiich is reinforced by a thicker border flange The oval aperture I88 (Fig. 2) in the ejector lever flange 599 is merely for convenience in machining adjacent surfaces, comprising the flat inner surface I 99 and the cylindrical end surface i Ill on a pair of laterally projecting guide flanges HI. These guide flanges, which are on both sides of the ejector lever 83, also have downwardly extending lips H2, with a diagonally extending face H3 for guiding the trunnions 63 into proper position. The lateral thickness of the reinforcing border flange I0! is such that it passes between the ends 69, 9'5 of the trunnions which are carried by the hood 4?.

The laterally projecting body 93 of the lower fixture I5 has each of its side webs 595 provided with the laterally projecting curved contact members IM. These arcuate contact members have lower partially cylindrical surfaces II5 for engaging the trunnions 93, against which they are urged by the spring 69, which bears on the erall'y projecting operating ring Hi. i has an aperture I42 like the ring 84, of sufficient top of the lateral extension -93 at the flange 92 (Fig. 1)

The side Webs I of the lower contact fixture 'are extended toward the left, in Fig. 1, to form the curved camming surfaces II 6, which engage the spring 69 in the installation of the fuse tube unit I2 and urge the fixed contacts H4 into proper engaging position with the trunnions 63.

The ejector lever 68 is also preferably provided with a pair of laterally projecting hammer flanges III, which are beveled at II 8 on the lower left corner to provide a sharp edge at H9. The sharp edge H5 is so located that it is adapted to penetrate between each trunnion 63 :and each fixed "contact II4. Thus the ejector lever has a sharp hammer flange, which is forced between the fixed and movable contacts to separate them when the fuse is blown and withdrawn by the ejector lever.

Referring to the upper contact supporting arm 38, it is supported on the insulator I3 in substantially the same Way as described with respect to the contact band 35 at the bottom. The two flanges of the arm 38 have apertures for the screw bolts I20, I2I, which also pass through an attaching flange I22 on the upper contact arm fixture 53 to secure this fixture to the upper arm '38.

The fixture 53 pivots on the bolt I2I by reason of the clearance provided by an enlarged aperture I23 in attaching flange I22 surrounding the bolt I20. This pivotal movement provides a predetermined amount of adjustment of the jaws of the upper fixture 53 to accord variations in length of the fuse tube unit I2 and still bring the upper trunnions I 24 into good contact engagement with the upper fixed contacts.

The screw bolts I20, I2I are provided with spring lock washers, thereby taking up any rattling and preventing the contact fixture 53 from pivoting too loosely.

The upper contact fixture '53 may comprise a cast metal member; and it is preferably formed with a housing having a pair of parallel side walls I integrally joined to a curved top wall HI and a depending back wall I32, forming a hood which is open at the bottom for receiving the upper end of the fuse tube unit I2 and for protecting the contacts and upper mechanism from snow, rain, and other weather conditions.

The upper contact fixture, on the fuse tube unit I2-, has a cylindrical body I33, with a cylin- 'drical bore for receiving the fuse tube I2, which is again secured in place by a plurality of screw bolts arranged like the screw bolts 11 of the lower fixture. The cylindrical body A33 has a reduced cylindrical extension I35, which is threaded externally to receive the internal threads of the cap I 52,, which is closed at its upper'end I36.

There is a bore I 37 extending through the fixture I GI and registering with the bore I 38 infuse tube I2 for receiving the fuse and its leader. At the upper right corner of the cylindrical portion I33 (Fig. 1) the cylindrical body "I33 is provided with a pair of laterally projecting cylindrical trunnions I24; and these trunnions I24 form the upper contacts carried by fuse tube unit I2.

At its lower end the cylindrical body I33 of the upper contact fixture IIlI has a partially zcyliln'drical extension Mil, which carries a lat- This ring size to pass the head on the laterally projecting pin of a disconnect stick by means of which the fuse tube unit I2 may be manipulated.

Ring I4! is used for operating the unit as a disconnect by merely pulling out and disconnecting the upper contact, While the unit I2 pivots on the lower trunnions. Ring MI is also used in the installation of the fuse tube unit to swing the unit upward from a position where the tube unit I2 depends from the lower trunnions 63 to the position of Fig. 1. 1

The parallel side walls I35 of the upper contact fixture are spaced sufficiently to receive the trunnions I24, which extend laterally from one side wall II)! to the other side wall I 0|. .Above the trunnions I24 the side Walls I0! may again have inner walls I43, which are spaced sufficiently to pass the cap I02, but which terminate in lower shoulders I44 located above the trunnions I24. In other words, the side walls of fixture 53 are offset at I43.

The lateral shoulders I44 are formed with-upwardly curved shoulders I45, above the trunn-ion I24 in Fig. 1, for reinforcing the spring contacts carried by the upper fixture 53 and preventing their belng strained too far. Trunnionengaging shoulders I44 curve upwardly and toward the right in Fig. 1, forming the upper wall of a tapering opening to guide the trunnions I24 into position to engage the upper contact springs.

At the lower part of the side walls I30 there is a similar downwardly and outwardly flaring surface I I-5 for'engaging the bottoms of the trunnions I24 and aiding and guidin them into engagement with the contact fingers.

The upper contact fixture 53 has an aperture I2"! in its rear Wall I32 and an attaching flange I28 extending rearwardly and upwardly. A plurality of leaf springs I56, I51 below, and I56, I57 above, are secured to the attaching flange 528 by screw bolts I48 passing through the springs and threaded into the flange I28.

The two innermost contact springs I56 have straight portions extending forwardly and terminate in partially cylindrical trunnion-engaging portions engaging the trunnion I24. Thereafter these contact springs I56 flare outwardly like the surfaces I44, I46, to aid in guiding the trunnions between the springs.

The two outermost leaf springs I5! have straight portions extending outwardly toward the trunnions and partially cylindrical portions at the trunnions engaging the outside of thesprings I58, for reinforcing the springs I56 and improving their tension. All four springs are initially tensioned toward each other so that they tend to close and present a smaller opening, which is spread when the trunnions I24 enter the flaring spring I56.

The trunnions I24 are retained in the partially cylindrical latching formations of the leaf springs I 55, into which they can be pushed by means of a disconnect stick, or from which they can be pulled with the same tool.

Operation The mode of manipulation and mode 'of'opera- $1011 of the mechanism is as follows: A fuse with its leader 98, arranged shown in Fig. 1, is first placed in the fuse tube unit it; then ejector ring I4I.

the trunnions I24 will cam the contact springs the fuse leader 98, tending to withdraw this leader from the tube I2 as soon as the fuse melts. The explosive tendency of the melting fuse, supplemented by the leader ejector 68, tends to break the circuit as quickly as possible and to extinguish the are inside the tube 12.

The fuse tube unit I2 having been re-fused, it is then hung upon a disconnect stick by means of the rin 84 in a position depending from the ring 84; and then the fuse tube unit may be lifted by means of the stick until the lip H2 passes over the trunnions 63-, as shown in Fig. 3; and the unit is hung on the trunnions 63 by means of the cylindrical portions IIO of the laterally projecting flanges I I I.

It should be understood that the trunnions 63 project laterally from each parallel side wall 54, 55, but terminate with a space between their ends, into which the ejector lever can be inserted. The laterally projecting flanges III on the ejector lever project far enough to extend over the inwardly projecting trunnions carried by the side walls 55 so that the ejector lever serves at this time as a support with which to hang the fuse tube unit I2 on the lower trunnions in its inverted position.

The operator then removes his disconnect stick from the ring 84 and places it in the ring MI, which is now lowermost. The operator then uses the disconnect stick to pivot the fuse tube unit I2 counterclockwise from the depending position described, upward on the trunnions 63 to the posiiton of Fig. 1.

As the fuse tube unit I2 passes from its upside down depending position to the position of Fig. l, the laterally projecting flanges I I I engage the trunnions 63 by means of their flat surfaces I09. As the fuse tube unit moves upward coun terclockwise gravity causes the fuse tube unit I2 to slide toward the left, in Fig, l, on trunnions 63, engagin surface I09, because the sur face I09 slopes downward toward the left. This brings the trunnions 63 into engagement with contacts H4.

As the upper contact fixture IOI approaches the contacts I56, I51 it is guided between the contacts by having its trunnions I24 guided by the flaring surfaces I44, I46 until the trunnions are forced between the contact springs I56. During this action the upper contact fixture 53 may pivot on its bolt I2i under the friction imposed by a spring lock washer on this bolt, the movement being permitted at the bolt I20 by the elongated slot I23. Thus the effective distance between the upper and lower contact arms is automatically adjusted to the length of the fuse tube unit; and variations in length of this unit will not affect its proper operation.

The curved contacts H4 engaging the trunnions 63 at the bottom have enough curvature and extend peripherally sufficient to overhang the back or left side of the trunnions 63 slightly. Thus the lower end of the fuse tube unit I2 is retained on trunnions 63, carried by hood 46. The upper end is retained by contact springs I56 engaging trunnions I24 on fuse tube unit I2. The fuse tube unit is now installed, ready to protect the circuit.

Operation as a disconnect To operate the cut-out as a disconnect, a disconnect stick may have its end hooked in the If the operator then pulls on the stick,

I56 apart to release the trunnions I24. When tacts is delayed until 10 the upper end of the fuse tube unit I2 is pulled in a clockwise direction, the unit will rotate on the lower trunnions 63 and may be swung in a clockwise direction until it depends from the trunnions 53 in the same position as it assumes when the fuse tube unit is first being installed.

When the fuse tube unit hangs from its lower contacts, this indicates the purposeful disconnection by the operator as a disconnect, as distinguished from the blowing of the fuse.

The operation of the cut-out on overload is as follows: Assuming that the fuse tube unit is in the position of Fig. 1, when an overload occurs, the fusible portion of the fuse 98 is melted by the electric current and ruptured, producing an explosive amount of gas, which passes out of the lower end of the lower fixture l5, expelling the cable leader 98, which is also pulled out by the fuse ejector arm 68.

The fuse ejector arm is urged in a clockwise direction by the compression spring 21 acting on the strut 88, which has a forked end engaging the ejector lever 63, pulling out the fuse leader 98.

As the ejector lever 68 rotates upon its pivot 9t, hammer flange H! has its sharp end moved toward the

trunnions

82, 63 until this sharp end engages between the trunnions in the fixed contact II4 on each side of the lower fixture I5.

This tends to raise the contacts H4; and the entire fuse tube unit is raised sufficiently for the overhang of the contacts H4 to clear the trunnions 62, G3; and simultaneously the contacts li l are urged outwardly toward the right, away from the

trunnions

62, 63.

This releases the lower end of the fuse tube unit i2 from the contact supporting arm 46; and the fuse tube unit I2 swings toward the right at its lower end in a counterclockwise position from the position of Fig. 1 to a position which corresponds to that of Fig. 2.

When the fuse tube unit is in this position, it is an indication that the circuit has not been opened by using the device as a disconnect; but it has been opened by the blowing of a fuse.

It will thus be observed that we have invented a fused drop-out-cut-out, in which the jet action of the expelled gases will tend to push the fuse tube unit into engagement with its upper and its lower contacts, retarding any tendencies of the device to open too quickly. The device will not open until the power arcs are extinguished because it is only after the arc is extinguished that the jet action ceases from pressing the fuse tube unit backwardly into engagement with its contacts.

The present assembly has the contacts so arranged that they are self-aligning to compensate for discrepancies in the length of the fuse tube units or in the spacing between the contact supporting arms, which are due to the variations in manufacture. The advantages of our improved device may be summarized as follows:

1. It is adapted to use standard universal fuse links of any manufacturer and to be handled according to conventional practise.

2. The lower contact of the fuse tube is ejected from the bottom contact arm upon rupture of the fuse link so that the fuse tube will hang with its opening extending downward after operation, thus protecting the interior of the fuse tube from all adverse weather conditions.

3. The construction of the mechanism is such that the mechanical opening of the lower conthe arc has been definitel extinguished. I y

4. The jet action from the lower end of the tube tends to keep the upper end of the fuse tube in its proper position and to hold the lower end in position until after the blast, thus delaying mechanical opening until the arc has been extinguished.

5. The resilient spring contacts with their wide flaring ends are adapted to register with the trunnions of the fuse tube units, even though the dimensions may vary due to manufacturing tolerances and the contacts may give sufficiently to become self-aligning as they engage the trunnions.

6. Any undue strain on the spring contacts is prevented by the provision of stop surfaces which take the thrust that is caused by jet action during rupture of a fuse.

7. The present fuse unit may be operated as a disconnect switch; but when so operated, its automatic mechanism is still trip-free so that a fault on the line will open the lower contacts, even while the operator is closing and holding the upper contacts.

8. The device gives a visual indication at all times whether it is actively in the circuit or whether the circuit has been broken purposefully at the top or automatically by rupture of a fuse at the bottom.

While we have illustrated a preferred embodiment of our invention, many modifications may be made without departing from the spirit of the invention, and we do not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of all changes within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States, is:

1. In a fuse tube unit, the combination of an insulating tube with a contact fixture, said contact fixture having a laterally projecting arm provided with a pair of flanges, a fuse throw-out lever pivotall mounted between said flanges, said flanges being provided at their lower ends with a pair of partial bearing formations to be supported on trunnions, and a hammer formation having a pointed end and located on each side of said throw-out lever for engaging below the partial bearings to lift the fuse unit off said trunnions when the throw-out lever rotates.

2. In a fuse tube unit, the combination of an insulating tube with a contact fixture, said contact fixture having a laterally projecting arm provided with a pair of flanges, a fuse throwout lever pivotally mounted between said flanges, said flanges being provided at their lower ends with a pair of partial bearing formations to be supported on trunnions, and a hammer formation having a pointed end and located on each side of said throw-out lever for engaging below the partial bearings to lift the fuse unit off said trunnions when the throw-out lever rotates, said laterally projecting arm being provided with an enlargement located axially with respect to the point of the axis of pivot, for supporting the fuse leader, and with clamping means engageable with said fuse leader.

3. In a lower contact structure for fuse tube units, the combination of an insulating support with a laterally projecting contact arm carried thereby and having a downwardly and forwardly open hood, a fuse tube unit having a laterally projecting arm to be received in said hood, and a fuse ejector lever having a camming extension engaging the top of said hood to counteract the mar-9i jet propulsion effect which is encountered when the fuse tube unit is, blown and the gas, escapes from the lower end thereof so that the ejector arm cannot open the circuit at said contact arm until the circuit is actually broken in the fuse tube unit.

4. In a lower contact structure for fuse tube units, the combination of an insulating support with a laterally projecting contact arm carried thereby and having a downwardly and forwardly open hood, a fuse tube unit having a laterally projecting arm to be received in said hood, and a fuse ejector lever having a camming extension engaging the top of said hood to counteract the jet propulsion effect which is encountered when the fuse tube unit is blown and the gas escapes from the lower end thereof so that the ejector arm cannot open the circuit at said contact arm until the circuit is actually broken in the fuse tube unit, said laterally projecting arm of said fuse tube unit carrying a pair of partially cylindrical bearing flanges, and said fuse ejector lever carrying an anvil formation for engaging below said bearing formations and lifting the fuse tube unit off its trunnions when a fuse is broken.

5. In a lower contact structure for a fuse tube unit, the combination of metal fixture having a through bore for receiving the open end of a fuse tube, said through bore terminating in a downwardly and forwardly open blast chute, said fixture having a laterally projecting arm provided with a cylindrical bore, a compression spring in said bore, a pair of parallel flanges carried by said arm and a fuse ejector lever pivotally mounted on said flanges.

6. In a lower contact structure for a fuse tube unit, the combination of a metal fixture having a through bore for receiving the open end of a fuse tube, said through bore terminating in a downwardly and forwardly open blast chute, said fixture having a laterally projecting arm provided with a cylindrical bore, a compression spring in said bore, a pair of parallel flanges carried by said arm and a fuse ejector lever pivotally mounted on said flanges, and a pair of partial bearing formations carried by said arm, one on each side of said ejector lever for resting on a. trunnion to be carried by a support.

'7. In a lower contact structure for a fuse tube unit, the combination of a metal fixture having a through bore for receiving the open end of a fuse tube, said through. bore terminating in a downwardly and forwardly open blast chute, said fixture having a laterally projecting arm provided with a cylindrical bore, a compression spring in said bore, a pair of parallel flanges carried by said arm and a fuse ejector lever pivotally mounted on said flanges, and a pair of partial bearing formations carried by said arm, one on each side of said ejector lever for resting on a trunnion to be carried by a support, the ejector lever being provided with a pair of knife'edge anvil members, one on each side of said ejector lever and located at such a radius with respect to the axis of rotation that the knife edge anvil passes immediately under said bearing formations when the ejector lever is rotated to lift the bearing formations off their supporting trunnions.

8. In a lower contact structure for a fuse tube unit, the combination of a metal fixture having a through bore for receiving the open end oia fuse tube, said through bore terminating in a downwardly and forwardlyoperi blast chute, said fixture having a laterally projecting arm pro.

vided with a cylindrical bore, a compression spring in said bore, a pair of parallel flanges caried by said arm and a fuse ejector lever pivotally mounted on said flanges, said ejector lever being provided with a groove at its end for passing a fuse tube leader and with an enlargement substantially at the axis of rotation about which the fuse tube leader is to be bent so that the fuse tube leader does not slide on said enlargement as the ejector lever rotates.

9. In a lower contact structure for a fuse tube unit, the combination of a metal fixture having a through bore for. receiving the open end of a fuse tube, said through bore terminating in a downwardly and forwardly open blast chute, said fixture having a laterally rojecting arm pro vided with a cylindrical bore, a compression spring in said bore, a pair of parallel flanges carried by said arm and a fuse ejector lever pivotally mounted on said flanges, said ejector lever being provided with a groove at its end for passing a fuse tube leader and with an enlargement substantially at the axis of rotation about which the fuse tube leader is to be bent so that the fuse tube leader does not slide on said enlargement as the ejector lever rotates, and. said fixture being provided with a threaded clamping member for clamping the end of the fuse tube leader.

10. A fuse tube unit comprising an elongated insulating tube provided with a metal contact fixture at each of its ends, the contact fixture at the upper end comprising a metal member having a bore for receiving said tube, and a removable cap for clamping one end of a fuse assembly, said latter fixture being provided with a pair of integral cylindrical trunnions aligned with each other and projecting laterally from each side of said latter fixture, and a lower contact fixture comprising a metal member having a bore for said tube, said tube being open at its lower end, said lower contact fixture having a laterally projecting arm provided with a bore and with a pair of bearing flanges, a throw-out lever pivotally mounted between said bearing flanges, and resilient means in said bore for urging said throw out lever in such a direction as to draw a fuse out of said tube.

11. A fuse tube unit comprising an elongated insulating tube provided with a metal contact fixture at each of its ends, the contact fixture at the upper end comprising a metal member having a bore for receiving said tube, and a removable cap for clamping one end of a fuse assembly, said latter fixture being provided with a pair of integral cylindrical trunnions aligned with each other and projecting laterally from each side of said latter fixture, and a lower contact fixture comprising a metal member having a bore for said tube, said tube being open at its lower end, said lower contact fixture having a laterally projecting arm. provided with a bore and with a pair of bearing flanges, a throw-out lever pivotally mounted between said bearing flanges, and resilient means in said bore for urging said throw-out lever in such a direction as to draw a fuse out of said tube, said laterally projecting arm being provided on each side with a pair of partially cylindrical bearing members, which face downwardly for engagement with trunnion members carried by another member for supporting the fuse tube unit.

12. A fuse tube unit comprising an elongated insulating tube provided with a metal contact fixture at each of its ends, the contact fixture at the upper end comprising a metal member having a bore for receiving said tube, and a removable cap for clamping one end of a fuse assembly, said latter fixture being provided with a pair of integral cylindrical trunnions aligned with each other and projecting laterally from each side of said latter fixture, and a lower contact fixture comprising a metal member having a bore for said tube, said tube being open at its lower end, said lower contact fixture having a laterally projecting arm provided with a bore and. with a pair of bearing flanges, a throw-out lever pivotally mounted between said bearing flanges, and resilient means in said bore for urging said throw-out lever in such a direction as to draw a fuse out of said tube, said laterally projecting arm being provided on each side with a pair of partially cylindrical bearing members, which face downwardly for engagement with trunnion members carried by another member for supporting the fuse tube unit, said throwout lever being provided with a rearwardly pointed anvil on each side for engaging below said partially cylindrical bearings to lift the fuse tube unit off said latter member when the said throw-out lever withdraws a fuse.

DAVID C. HUBBARD. WILLIAM L. HOLLANDER.

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

UNITED STATES PATENTS Number Name Date 2,028,421 Steinmayer Jan. 21, 1936 2,354,907 Bennett et al Aug. 1, 1944 2,537,348 Hubbard et a1. Jan. 9, 1951 2,547,160 Hubbard Apr. 3, 1951 2,558,957 Hubbard et a1. July 2, 1951