US2702842A - Cutout construction - Google Patents

Description

Feb. 22, 1955 H. G. JEPSEN ET AL CUTOUT CONSTRUCTION Filed July 24, 1953 United States Patent CUToUT CONSTRUCTION Hans G. Jepsen, Racine, Wis., and Russell A. Wood,

Jeannette, Pa., assgnors to McGraw Electric Company, Milwaukee, Wis., a corporation of Delaware Application July 24, 1953, Serial No. 370,138.

8 Claims. (Cl. 20G-127) ThisV invention relates to cut-out constructions.

This invention is an improvement over that disclosed in the prior patent, No. 2,357,722 granted to Willlan'i` O. Schultz on September 5, 1944, for Cut-out Construction, assigned to the same assignee, by mesne assignments, as that of the present invention.

lt is an object of the present invention to provide a cut-out construction which is adapted to interrupt both low amperage and high amperage faults equally well, with conventional distribution fuse links.

It is' another object of the present invention to provide a novel cartridge structure for an open-type fuse cutout, which cartridge includes a vent control means arranged to' provide single venting of the fuse cartridge on low current faults and double venting on faults up through the maximum interrupting capacity of the cutout.

It is a further object of the present invention to provide an expendable cap secured to one end of a fuse cartridge, which cap includes a diaphragm portion integral therewith operating to allow venting from` both ends of the tube at predetermined interrupting current to provide a compensating recoil action, which causes a minimum of stress on the cut-out throughout its maximum interrupting capacity rating I-t is still another object of the present invention to provide a fuse cut-out wherein the recoil action of the cartridge on interruption of the fusey link is completely absorbed by the bottom hinge structure and wherein the top contacts are not subjected to mechanical stress under fault conditions.

An embodiment of the invention is shown in the accompanying drawing, in which:

Fig. 1 is a side elevation of a cut-out in the form of an open type drop out fuse incorporating the essential portion of the present invention.

Fig. 2 is an enlarged fragmentary view, partly in section, showing the controlled venting means for operating with the fuse cartridge.

Referring to the drawings, it will be seen that the device comprises an elongated insulator 1, supported by a hanger 2 intermediate its ends, which hanger is supported by a mounting bracket 3. The mounting bracket 3, as shown, is particularlyv adaptable for cross-arm mounting. Upper and lower terminal members are indicated' generallyv by the reference characters 4 and 5;

The upper and lower terminal members may be secured to the insulator in any suitable manner. For example, the lower terminal member S is secured by means of a strap which encircles the lower portion of the insulator'l and is held clamped by means of a bolt as indicated. A cast member 7 is bolted to the clamp 6, as shown, and this member is provided with a pair of t-runnion supports in the form of hook members S, which are spaced apart and which are provided with overhanging portions 9. The cast member 7 extends downwardly and is provided with an eyelet portion 1i) to which a conductor may be tied and with a connector or clamping member 11, whereby the conductor may be electrically joined and mechanically clamped to the terminal.

The upper terminal 4 is similarly provided with an eyelet portion and a connector portion indicated at 12 and 1:3, respectively.

A drop-out fuse tube is provided and is indicated by the reference character 14. This tube is equipped with a sleeve-like member 15 at its lower end which ts snugly over the lower end of the fuse tube. It is rigidly securedV to the lower portion of the fuse tube in any suitable Patented Feb.. 22, 1955 ice manner. For example, it may be pinned to the fuse tube, as shown in Fig. 1. A downwardly and rearwardly extending arm 16 is formed integrally with the sleeve member 15Y and is provided with a keyhole-shapedrv eyelet 17, which maybe engaged by a switchstick when lifting the fuse tube out of service after it-hasdropped to open position, or` replacing itin the trunnion support in a well known manner.

A fuse link extracting lever 18 'isr p'votally mounted as indicated at 19 to the arm 15 and is provided' with a thumb nut 20 screwed on a threaded pin= rigid with lever 18 to clamp a ilexiblealeader 21 of a fuse link to the lever. The fuse'li'nk may be of anyy desired construction and, as shown in Fig. 2, may' have a reduced' fusible section 22 adjacent' its upper portion and may be termi# nated in a 'button head 23 at its upper end. The lever 18 is approximately channel-shaped at its rear portion, and is provided with a pair of outwardly' extending trunnions 24 which project outwardlyfrom the side walls of the lever 18; These trunnions areremovably received within the trunnion supports or hooks 8. It is to be noted that the trunnions 24' can not be detached from the trunnion supports 8 until' the fuse tube has rocked. downwardly to inoperative position. Thereafter, as stated, the fuse tube mayzbe lifted from the trunnion supports: by means of a switch stick in the usual. manner'.

The upper terminal 4 is secured' to the upperend of the insulator 1 by means of a bolt, as shown, a nut being positioned in a' recess in the insulator I and an insulating cap covering the outer end of the boltV so as to prevent birds sitting on the hanger 2 from reaching any live portion of the upper terminal member. The specific arrangement illustrated has been fully described and claimed in U. S. Patent. No.; 2,555,158, granted to W. O; Schultz for Pretensioned Spring Contact for Cut'outsA on Mayl 29, 1951 and assignedto the same. assignee as is the present invention. T het upper terminal 4` is provided with an outwardly extending arm 30f and a spring portion indicated generally' by the reference character The arm, or stationary portion 30 is provided with a recessed relatively narrowV neck 32 and with outwardly projecting rounded parts 33:,` A transversely extending'Y pin 34 projects: from opposite sides.` of the stationary portion.,

The spring portion of the contact structure comprises a generally U-shaped`r main body portion' or arms 35 whose bail part 36 is pivotallyV supported by a lipz 37' integral with the stationary member 30' andslightlyy bent upwardly rearwardly of` the bail portion: to loosely and'` pivotally retain. the bail portion in place.`

The main arms 35 continue outwardly and are provided withY downwardly curving shoulders 38 behind which the pins or projectionsl 39 of the upper terminal 4t) on the fuse tube are adapted toy normally seat. The upper portionl of the fuse may comprise` the' sleevelike member 40, which is=` rigidly secured, as by pinning or other means to thev fuse tube. Preferably a manipulating eyelet 41 is` formed integrally with the upper terminal member 40;

The downward pressure imparted by the arms* 35` of the spring portionl 31. provides a yielding lockingy of the cut-out in closed position. The main arms: 35. continue forwardly and are diverted at their ends and curved upwardly as indicated. by the reference character 42. The spring: arm continues rearwardly by a pair of upper spring arms 43, all; portions of the springA it being understood, being integral- The spring arms 43 extend rearwardly and downwardly-and: are. positioned below the rounded projections 33 on the stationary portion 30;

It is to be noted particularly that these spring arms 43 bear not only against the projectionv portions. 33, but also bear against the narrow necky portion 32 ofthe stationary member 30 and thus aii'ordsy an excellent. connection between the spring portion of. the contact indicated generally at 31 and the stationary member 30'.

It is to be noted that the pins 34 limit the downward motion of the arms 35 of the springy member when the spring member is in open position.

A novel feature of the device rests in the meansv for controlling the venting of the fuse tube d'uri'ngv rupture of the fuse link, as will' hereinafter be described. This means preferably takes: the form'- of an expendible cap which threadingly engages the outer extremity of the upwardly extending neck portion 45 formed integrally with the upper terminal 40 of the fuse tube 14. The cap 46'may be formed of any suitable material and is screwed in place until it preferably contacts the button head 23 of the fuse link, as shown in Fig. 2. The button head makes contact with the conducting neck portion 45, as shown in Fig. 2. The downward pressure from the spring member 31 on the trunnion 39 is transmitted through the lever 18 to tension the fuse link towards separation on rupture. This tensioning will also provide excellent electrical contact between the fuse link and the upper terminal 4. The cap 46 is preferably of a conducting metal, which may be machined to prescribed tolerances. to provide a frangible section 47. A novel manner of providing a frangible section is to machine the blank to provide a marginal shoulder portion 48 and a projection 49 iointly defining the frangible section 47.

In the operation of this apparatus it will be seen that when the fuse link ruptures under overload conditions, the lever 18 will be released and the lower end of the fuse tube will move downwardly and outwardly, thus allowing the projections of pins 39 of the upper terminal of the fuse tube to disengage themselves from the arms 35 of the upper spring contact 31. The fuse tube will thereafter rock downwardly to inoperative position (not shown). Gravity assists in this action but the principal downward force acting on the fuse tube is obtained by the heavy downward pressure exerted by the spring contact member 31 through the arms 35, and inasmuch as the pivot 19 is located forwardly of the trunnions 24, the fuse tube will be biased toward drop-out motion.

If a light overload condition occurs, the usual expulsion action takes place with a consequent drop-out motion of the fuse tube. The upper end of the fuse tube is completely enclosed. This allows suiiicient pressure to be built up in the tube to clear faults of the smallest magnitude.

When operations occur from a severe short-circuit, the violent explosion, which would burst the cartridge of a cnt-out of lower interrupting capacity, is automatically relieved by the vent arrangement at the top of the cartridge. The frangible section 47 in the expendible cap 46 operates to allow venting from the top as well as the bottom of the tube. This double venting provides compensating recoil action which causes a minimum of stress on the cut-out throughout its maximum interruptina capacity rating. The position ofthe fuse link button 23 is above the upper contact arms 43 and can be expelled unimpeded. With the top of the cartridge as extended r by the neck portion 45. in this position there is nothing that would tend to detiect the gases and cause external ashover.

After operation, the cartridge drops out in a conventional manner to swing and hang downwardly from the trunnions 24 (not shown).

When the device is'to be refused, the lineman lifts the fuse tube from the lower trunnion supports by means of a switch stick engaging within the eyelet 17. The cap 46 is backed off the threads of the neck portion 45 and may be thrown away in cases where the frangible portion 47 has been ruptured because of excessive overload conditions. However, after rupture of the fusible portion, a new fuse may be inserted in the fuse tube and secured to the thumb nut 20, as shown in Fig. l. Thereafter the fuse tube is replaced in the lower tmnnion supports 8 by means of a switch stick. The lineman then disengages the switch stick and engages it in the eyelet 41 and rocks the fuse tube upwardly into operative position, as shown in Fig. l.

It will be apparent that in the case of high short circuit interruption, the lineman will have to replace the expendible cap with an entirely new cap.

Although the recessed portion of the cap may take the form of the shoulder 48, it is conceivable the cap may be grooved or otherwise machined to rout out material from the inner surface (not shown) to provide an annular frangible section.

The projection 49 joining the marginal shoulder portion 48 also acts to provide a visible indicator to distinguish the expendible cap from conventional cap members placed on ordinary cartridges provided to interrupt relatively low current Lfaults., In` addition, the projection has been found to provide consistent interruption characteristics results on heavy overloads, which would be very unlikely if the cap had a at surface across the top.

It will be apparent that there has been provided by this invention a cut-out construction which effectively utilizes an expendable and consistently operable vent control means for the fuse cartridge, which will permit desired arc expulsion on low current faults and double venting of the tube on faults of relatively high values up through the maximum interrupting capacity of the cut-out.

We claim:

1. In a fuse construction, stationary terminals, a fuse tube having a 'terminal at one end and open at the other end normally electrically connected to one of the stationary terminals, a fuse link having a button head and extending through the fuse tube and electrically connecting the other stationary terminal and having a head engaging one end of the fuse tube and normally in contact with the terminal of the fuse tube, and a cap normally threadingly engaging the terminal and closing the said one end of said fuse tube, said cap having a frangible portion integral therewith, whereby said fuse link head and a portion of said cap may be blown outwardly when sutlicient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

2. In a fuse construction, stationary terminals, a fuse tube having a terminal at one end and open at the other end normally electrically connected to one of the stationary terminals, a fuse link having a button head and extending through the fuse tube and electrically connecting the other stationary terminal, and a closure cap normally threadingly engaging the terminal of said fuse tube and having a marginal recessed portion defining a frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when suflicient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

3. In a fuse construction, stationary terminals, a fuse tube having a terminal at one end and open at the other end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal, and a cap normally closing the said one end of said fuse tube and having a marginal recessed portion defining a frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

4. In a fuse construction, stationary terminals, a fuse tube having a terminal at one end and open at the other end normally electrically connected to one of the stationary terminals, a fuse link having a button head extending through the fuse tube and electrically connecting the other stationary terminal, and a cap normally closing the said one end of said fuse tube and having an annular marginal recessed portion dening a frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when suiiicient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

5. In a cutout having a movable fuse tube including a terminal at one end and open at the other end and a fuse link having a button head contained therein, a contact assembly comprising a stationary member provided with a guiding head, and a spring member having U-shaped arms supported adjacent their bail portion from said stationary member and located on opposite sides of said guiding head and arranged to engage said fuse tube terminal, said spring member having rearwardly projecting arms extending from the outer ends of said U-shaped arms and pre-tensioned for movement towards each other; a cap normally closing the said one end of said fuse tube and having a marginal recessed portion defining frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when sutiicient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

6. In a cutout having a movable fuse tube including a terminal at one end and open. at the other end and a fuse link having a button head contained therein,

a contact assembly comprising a stationary member provided with a guiding head, and a spring member having U-shaped arms supported adjacent their bail portion from said stationary member and located on opposite sides of said guiding head and arranged to engage said fuse tube terminal, said spring member having rearwardly projecting arms extending from the outer ends of said U-shaped arms and pre-tensioned for movement towards each other; a cap normally closing the said one end of said fuse tube and having an annular marginal recessed portion defining frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

7. In a drop-out fuse construction comprising an upper and lower stationary terminal, a fuse tube having an upper terminal and being open at its lower end, a fuse link in said fuse tube having a button head and electrically connecting the upper termina] of said fuse tube with said lower stationary terminal, a U-shaped spring contact mounted on said upper stationary terminal having detachably interlocking engagement with the upper terminal of said fuse tube and biasing said tube toward downward motion, lever mechanism pivotally supporting said fuse tube from said lower stationary terminal for drop-out rocking motion, said lever mechanism controlled by said fuse link and normally holding said fuse tube in operative position and releasing said fuse tube when said fuse link is ruptured; a cap normally closing the upper end of said fuse tube and having a marginal recessed portion defining a frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when suicient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

8. In a drop-out fuse construction comprising an upper and lower stationary terminal, a fuse tube having an upper terminal and being open at its lower end, a fuse link in said fuse tube having a button head and electrically connecting the upper terminal of said fuse tube with said lower stationary terminal, a U-shaped spring contact mounted on said upper stationary terminal having detachably interlocking engagement with the upper terminai of said fuse tube and biasing said tube toward downward motion, lever mechanism pivotally supporting said fuse tube from said lower stationary terminal for drop-out rocking motion, said lever mechanism controlled by said fuse link and normally holding said fuse tube in operative position and releasing said fuse tube when said fuse link is ruptured; a cap normally closing the upper end of said fuse tube and having an annular marginal recessed portion defining a frangible section integral therewith, whereby a portion of said fuse link and at least a portion of said cap may be blown outwardly when sulcient pressure is developed in the fuse tube upon rupture of the fuse link responsive to heavy overload conditions.

References Cited in the le of this patent UNITED STATES PATENTS 1,853,093 Steinmayer Apr. 12, 1932 2,179,749 McCluskey et al Nov. 14, 1939 2,358,684 Brown Sept. 19, 1944 2,390,670 Steinmayer Dec. 11, 1945

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