US2429518A - Power fuse - Google Patents

Description

Oct. 21, 1947. w. D. KYLE, JR., l-:T AL

POWER FUSE Filed April l5, 1943 wu L/Am ZJ. m45, J.

im m1 U. M m N H vthe operative condition of Patented Oct. 21, 1947 UNITED PATENT? orrlc PowER Yan Ryan. Southy .Kyle Qomorotlon, South D. lygle Je Milwinulree, and Anthony Milwaukee, Wis., assignorsto crporationofwisconsln Application. laprifl` 15, 1943,'54115241 4No,248,31559 `2 1 claim.' (otono-11o) -power fuse in which isoavoided- :the characteristic .deoiences of .conventional liquid fuses, `and wherein the :fuse housing frequiresno liquid-tight seals.

tusewhich While obo Another .object isz-to devise a powerv will quickly iinterrtipt.y a. fheavycurrent Yrioting all .-possibilityof .a leakage :path 4of ,conse- .quential A-pr@portions being established :following a. luseoperation.

Still afnotherobjeot isA to provide afpowerY vfuse which cani readily-be `determined` by visual -inspectiom without Ydisvrnentling.

A further object is to K `which can easily be rehabilitated in the field at va cost which iscbut'o fraction pfthat-of ain entire 4fuse assembly.

-An additional Aobject is 'to devise a power fuse which will- Iblowwithout an accompainyingyiolent explosion sind, therefore,z will neither brustnor produce an objectionably 'loud report,v norgive oil objectionable :fumes or become Lhot Qn being left r`inthe circuit,

One lembodiment ofpour invention is depicted in lthe -drawing, -wherein,:

Fig. g1 is a long itudinalsectional View of @cornplete fuse assembly, exclusive of the ln'iounting structure therefor i,

Fig. 2 is a longitudinal sectional yiew ora fuse insert or cartridge constituting a. replaceable component of the fuse assembly `a constituent part of the inse-111311;

Fig- 3 is. en elevational view, of ,the -fuse assembly, drawn to a. smaller scale than Fig. 1;

Fig. ,4 is a cross-Sectional View tglren vatlorvig provideV a ,power Afuse Vtue or .which the enclosed e4 fusedl T,tridee or. rinsert 2 together withal helioalfretrect:

Fie. 6 isf .cross-,sectional Ylew .teken et ,liuc The entire ,fuse .esoembls es shownA eechoi ,Figo l endY 3 kiso self-.contained unit adopted. ,to be withdrewebly mounted er1-,ev suitable support.,

not shown, .having the.' .11511.31 ,line ilcrmrlalslld spring '.clinsor other .attachment moons by Arir- ,assembly ncon ycoolly eine quickly vvloe mounted. Fusomounts oi vthatruit-.lire :being thorouehlyifamiliar to those who arecon- .cerneolwiththis ort, it lthought unnecessary to illustrate ce exeiriple thereof in .the presenteey111ication.

` 'lillel fuse shown includes. e. housing l in kwhich k ecorriprising o inse, cerf :ine spring and vci flexible .conductor 4 which ,shoots the spring and -isfcooriected at its lower end to the-.fuse cartridge .and .anchored .at its upper extremitytov the housing.

The housing Acomprises .e treusoarentfigloss. or .transparent yplalstic vtube 5j. fior exemple, Luoite ,which-.is mane `loog enough, et 1east..;to.sccuf.e the requisite spacing between its metehooooed ends whereby to kensure..eetlust.eroine-oro: fol-lowing la, 4use blowout.. Attached to the upper end Aof .tube L5 is1 e metY ferrule flffthis .being firmly se,- curel to the tube bycement or fusible metal, as iooicoted et L Ferrule lois designed -to.,.e.neage suitable ,terminal clips,f not shown, by means. of which the fusefelssemblyis-mounted1 Tlie der 'sien of this ierrule, es well the lower .ferrulo to. be, .described flater, is. of course. adaptable to accommodate whatever vstyle of mounting it kmet buttonfllke member .Il which, .forms the -llDRer terminal of the ooniprisixig parte@ .Lond .4. in avidi-tion to other ports ,de- `scribedhe.reiueiter.

To theflower .enclfofiubeis secured a second v1;f ;,ete.l .forrule ll.. This-.is designedtoocoommodetearmounting `.clio` and threaded, externally @t .L4 ,to receive ,a remoxablecap t5, a

' number of openings -ll through which .the liu-lgs incidental to thellolowing of ,controllecharge freely into the surrounding atmosphere. Cap functions as a receptacle to catch the detached fuse parts which drop down when the fuse blows, and, conjointly with ferrule l2, to grip the flexible leaders of the fuse cartridge and thereby establish electrical connection between ferrule l2 and the lower terminal of the fusible section, as presently will be described.

The fuse-link assembly comprises cartridge or insert 2 (detailed in Figs. 2, 4, and 5), retracting spring 3, flexible conductors 4, of which two are shown in parallel, and the button-like terminal member The upper end of the cartridge is detachably connected to the lower end of spring 3 and to the lower end of conductors 4 through the medium of a conductive member Il.

Fuse cartridge 2 (see Figs. 2, 4, and 5) comprises a metal sleeve |8 which is reduced in external diameter at its upper end and externally threaded at I9 to engage a corresponding internal thread in member l1. This serves to anchor the upper end of the cartridge to member and, in turn, to spring 3 and iiexible conductors Il. Sleeve i8 is internally threaded at 20 to engage a non-conductive tube 2| which may be made of horn ber; and said sleeve has an internal shoulder at |8a which co-operates with the upper end of tube 2| to grip the external iiange 22a of a, metal insert 22 which is bored to form a conically tapered seat for the frustroconical lower end of a sheet metal receptacle or capsule 23 in which is stored under pressure a suitable arc-extinguishing gas. Capsule 23, which may be a commercial soda water bottle charging unit lled with carbon dioxide, and commonly known as a Sparklet bulb, is held in its seat by means of a metal disc 24 which presses against the upper end thereof and is locked in place by ears |82) which are bent over the peripheral edge of the disc. The lower end of capsule 23 is closed by means of a thin metal disc 23a which is adapted to be punctured quickly when subjected to an arc impinging thereon. Puncturing said disc releases the enclosed gas.

Situated immediately below insert 22 and supported on an internal shoulder 2|a formed in tube 2| is a nozzle member 25 having a. bore which is conically ared at 25a and straight at 25h. The straight portion of the bore is diametrically constricted, as shown, in order to form a conned passageway immediately below the lower end of capsule 23, in which passageway the gas discharged from the capsule can be concentrated on the arc which forms when the fuse blows. Sleeve 2i is made, preferably, of refractory, nongas-evolving material such as porcelain or lava The bore diameter at 25h should be smaller than the outside diameter of the neck forming the lower end portion of capsule 23 so that the arc will invariably be concentrated on the aforementioned disc. If the arc is not thus directed, but, instead, is permitted to wander, there may be undue delay or even failure to puncture the receptacle. Hence, the aforementioned bore diameter is a critical factor and constitutes one of the features of this invention.

Metal insert 22 is slotted externally and axiswise at two diametrically opposite sides, the slots being identified by reference numerals 22h and 22e respectively. Slot 22o receives the upper end of a fuse wire 26, which is soldered in place therein; and slot 22h receives the upper end of a strain wire 27 which similarly is soldered in said slot and is threaded through an aperture 22d from the bore of insert '22. Sectional view Fig. 4, considered in conjunction with Fig. 2, shows clearly the slots 22h and 22o and the disposition of strain and fuse wires, respectively, therein. Said strain and fuse wires pass downwardly through narrow cross-slots 25d and thence through constricted bore 25h and into the flared passageway 25a, where they are connected at their lower ends to a solderless compression connector 28. Crossslots 25d are shown most clearly in Fig. 6 wherein the fuse and strain wires have been omitted for the sake of clarity.

To prevent the fuse and strain wires being twisted there is secured to connector 28 a washer 28 having oppositely disposed up-turned peripheral ears '29a and 29h (see especially Fig. 5) which are seated in corresponding notches 25e formed in the lower end of nozzle member 25. Thus washer 29 is restrained against rotation and, in turn, serves to prevent rotation of connector 28 and the fuse and strain wires.

Attached to connector 28 and depending therefrom are two parallel, stranded, flexible conductive leaders 30, 3| which, as shown in Fig. 1, are intended to be clamped between lower ferrule 2 and lower cap 5-the ferrule being slotted at |2a and |22) to provide recesses for accommodating the flexible leaders.

Normally the fuse cartridge is anchored down in its lowermost position by the clamping of nexible leaders 30, 3|. This puts spring 3 under tension and, accordingly, biases the cartridge t0- ward movement upwardly, which movement normally is prevented by strain wire 21. When the latter is severed, concurrently with the blowing of the fuse wire, the cartridge is quickly drawn up by spring 3-thereby effecting an abrupt separation of the fuse wire and strain wire terminals and a consequent stretching out of the arc. Blowing of the fuse wire and incidental severance of the strain wire, as well as the fuse wire, on either an overload or short circuit causes an arc to form within the constricted passageway 25h. The upper end of the arc is instantly transferred to the lower end of capsule 23, and the thin disc 23a is immediately punctured so that the gas therein is released in the form of a high velocity jet or blast which impinges directly upon the arc. All this occurs within a fraction of a Cycle after the fuse wire blows, and at the same time the arc is being rapidly lengthened by virtue of the upward movement 0f the cartridge. The deionizing effect of the gas coupled with rapid elongation of the arc gap generally results inv extinguishing the arc at the first current zero following severance of the fuse wire.

an arc, it follows that blowing of the fuse is not accompanied by a loud report, and no great amount of pressure is developed such as would be apt to burst the cartridge or the housing.

Fiber tube 2| does, no doubt, evolve some gas; but its inside diameter is relatively large and its exposed internal surface is both short and of small area. Hence no great amount of pressure is engendered by reason of the ber tube. When the fuse has blown and cartridge 2 has moved upwardly under the retractile force of spring there is no medium intervening the severed ends of the fusible sectionwhich, by reason of carbcnization, could presenta substantial lealrage path. This follows Yfrom the fact that tube 5, whether of glass or Lucite, is not sus- Ais 4made possible by uter to `withdraw ber 11.

power fuses.

receptacle, a lfusible cartridge, one terminal of said fusible section beting attached to said cartridge and the other terminal thereof being anchored otherwise than 4by.attachment to said cartridgaa spring operaitive to move said cartridge away from the anchorage of said .other terminal and effective to separate said terminals of said fusible section, theigas from said receptacle into the space with- Iinsaid kcartridge traversed by the `arc which results from blowing said fusible section, said means Aconcurrently with `nalsiby said spring means.

ceptible to carbonization yand 'provides no conductive surface; Kand the use of these materials the avoidance of bursting pressures, rlChis is an important rfeature in a power :fuse and -one vwhich is inherent inthe illustrated fuse v`structure and entails Vno `added cost.

-As'willbe self-evid-ent,itis a very simple inatthe entire fuse-link rfrom the -housing and to detach the cartridge from `mem- Hence, thecartridge can readily bereplaced in the field by Va service man; and the cost of a replacement cartridge -is a relatively small part of lthe cost of the yentire fuse assembly.

*inasmuch as extinguishmentof the arc is not 'dependent uponevolutionof gas, the volume and expulsive action'of which'is predicated upon the intensity of the arc, it follows that an arc of 'lowfcurrentvalue is yextinguished just as readily :as a heavy lcurrent arc; l-has to be made for extinguishing low-intensity and lno special provision 'arcs as ymust `be done in some other ytypes of Herethe volume of arc-extinguishing gas andthe force of its discharge is constant, irrespective of the intensity of the arc.

What is claimed is:

l. In a fuse, the combination with a fusible section having an anchored terminal and a movable terminal, of spring means for abruptly moving the movable terminal of said fusible section away from the anchored terminal yupon severance ofrsaid fusible section, a source of arc-extinguishing gas under pressure adjacent the movable terminal land movable therewith, means Aoperative in response to an arc resulting from the severance of said fusible 'section for releas- Ling said -gas immediately adjacent said arc concurrently with Athe separation of said terminals vby said spring means, and a passageway for dilrecting said gases intolthe path of said arc.

`2. in a fuse, a cartridge including a gas-filled section enclosed withinsaid abruptly upon severance and vmeans for releasing release the gas as aforesaid the separation of said termib-eing operative to .3, A fuse-link comprising a fusible section,

-means for anchoring one end of said fusible section, spring means for retracting the other end cfsaid yfusible section upon blowing of the fuse whereby abruptly `to elongate the arc which is "formed 4between the terminals of the fusible -sec- Ttion, a source of arc-extinguishing gas under `)pressure disposed space in which said arc is formed, and means in operative relation to the responsive to the arc for releasing the gas from :said source into said space to assist in the extinguishment .of said arc supplementally to and concurrently with the arc-extinguishing action vof fsad spring means, said spring biasing said sourcerinzthe direction ofretraction of said other zend.

`4.The combination `in ra fuse-link of a cartridgenclosing a conductive .receptacle filled with" foo /to the lower ends of arc-extinguishing gas under pressure, 1a kfusible `conductor :disposed within said cartridge adjafcentone end of said receptacle and sorarranged relative lthereto that on blowing :of the fusible Iconductor vthe rresultant arc is in series circuit with said receptacle, oneiendvonly of said fusible `conductor being `anchored toisaid cartridge, the other end of said fusible conductor being ar- :ranged v to be attached to an anchorage vextraneous Athe fuse-link, the disposition of said fusilole conductor relatively to said receptacle being such lthatithe arc which results 4from blowing of .the fusible `conductor will .quickly puncture said receptacle and thus release therefrom a jet of gas directedat-the arc, and a spring for biasing said cartridge toward movement in a direction effective to separate the severed terminals of vsaid fusible conductor following a blowout.

J5. The combination in a fuse-link of a cart- 4ridgecomprising a metallic sleeve, a tube of insulating material `detachably connected to and depending yfrom said sleeve and co-axial therewith, a removable receptacle filled with arc-extinguishing gras under pressure disposed vwithin saidsleeveya nozzle member of non-gas-evolving *non-conductive material disposed within said vtube immediately below said receptacle and hav- .ing a constricted passageway immediately adja- 'cent the lower end of said receptacle, a fuse wire one end to the lower ends of said strain -`wire and fuse wire, a ytension spring detachably connected tothe upperend of said cartridge for biasing said lcartridge upwardiy, and means operative in responseto an are resulting from the severance of said fuse wire for releasing said arc extinguish- -ing gas.

6. The combination in a fuse-link of a cartridge lcomprising a metallic sleeve, a retracting spring vdetachably connected to the upper end of said metallicsleeve, a'tube of insulating material `detachably connected to and depending from the lower end of said metallic sleeve and co-axial therewith, a metallic insert within said cartridge Aand secured between said sleeve and tube jointly,

Asaid insert having a conically tapered bore, a gas 50 icontainer within the bore of said sleeve and seated at its lower end in the conically tapered bore of vsaid insert, a nozzle member of non-conductive, non-gas-evolving material disposed within said tube immediately below said metallic insert and having a constricted axial passageway kimmediately below said gas container, a strain lwire-and a fuse wire each connected at its upper end to said metallic insert and extending downwardly through said constricted passageway, a flexible conductive leader connected at one end said fuse wire and strain wire and extendingfoutwardly from the lower end o'f said cartridge, a terminal member attached to the upper end of said spring, a flexible conductor 4extending axially through said spring and electrically interconnecting said terminal member iwith said metallic sleeve, and means operative in vresponse to an arc resulting from the severance of said fuse wire for releasing said gas immedi- .ately adjacent said arc.

17. The combination in a cartridge, a receptacle .ing gas under `pressure fuse-link of a tubular containing arc-extinguishdisposed within said cartridge, a nozzle member made of lsubstantially nongas-evolving, -non-conductive material having -a constricted axial passageway immediately adjacent and below said receptacle, a fuse Wire extending through said passageway and anchored at its upper end above said passageway, the lower end of said fuse wire being provided with means vfor eiecting anchorage thereof extraneously of said cartridge, a retractile spring connected to the upper end of said cartridge for moving said cartridge lengthwise to eiect abrupt separation of the terminals of the severed fuse Wire when a blowout occurs, and means operative in response to an arc resulting from the severance of said fuse wire for releasing said arc extinguishing gas immediately adjacent said arc concurrently with the separation of said terminals by said spring.

8. The combination in a fuse of structure including a receptacle containing arc-extinguishing gas under pressure, said receptacle having a portion constituting an alternate arc electrode, said portion being quickly perforable by the arc when caused to operate as an arc electrode, a fusible element having one terminal only electrielTecting electrical connection with and for anchoring the other terminal of said fusible element, said portion being so positioned with respect to the terminals of said fusible element that after a blowout has occurred the shortest arc path is between said portion and said other terminal, and spring means for biasing the terminals of said fusible element apart to eiect abrupt separation thereof when a blowout occurs.

9. The combination in a fuse, of a tubular cartridge, a receptacle containing arc-extinguishing gas under pressure, said receptacle being disposed within said cartridge, a conductive member situated within said cartridge and bored axially to form a seat for said receptacle, the lower portion of said receptacle projecting downwardly through and beyond said conductive member, a non-conductive member situated below said receptacle and said conductive member and having a constricted bore which is obstructed at one end by the lower end of said receptacle, a fuse Wire and a strain wire in parallel and each connected spouse to an arc resulting from the severance of said fuse wire for releasing said arc extinguishing gas immediately adjacent said arc.

l0. The combination in a fuse, of a tubular transparent housing, and a tensioned fuse-link within said housing and comprising a tensioned coil spring and a fuse said metallic sleeve and containing arc-extinguishing gas under pressure, said receptacle being generally cylindrical in form and having an attenuated neck portion at one end which seats in said frustro-conical bore and projects through and beyond said consaid tube and immediately adjacent said conductive member, said nozzie member having a constricted bore terminating at one end immediately adjacent the end of said neck portion, a fuse wire and a strain Wire in parallel, each connected at one end to said conductive member and extending through said constricted bore, a flexible conductive leader connected to the other ends of said fuse and strain wires, said leader being anchored to said housing and serving conjointly with said strain wire to maintain said fuse-link under tension and means operative in response to an arc resulting from the severance of said fuse Wire for releasing said arc extinguishing gas.

l1. In a fuse, the combination with a fusible section having an anchored terminal and a movable terminal, of spring means for abruptly moving the movable terminal of said fusible section away from the anchored terminal upon severance of said fusible section, a source of fluid arcextinguishing material under pressure adjacent the movable terminal and movable therewith, means operative in response to an arc resulting from the severance of said fusible section for releasing said material immediately adjacent said arc concurrently with the separation of said terminals by said spring means, and a passageway for directing said arc extinguishing material into the path of said arc.

with said sleeve metal insert disposed within one end portion of said sleeve and co-axial with said sleeve, said insert being secured in place by said tube and removable from said sleeve after detaching said tube from said sleeve, said insert forming, in conjunction with the bore of said sleeve, a chamber, a gas-nlled capsule disposed within said chamber, said insert being bored through axially provide a seat for one end of said Way, and means operative in response to an arc resulting from the severance of said fusible member for releasing said gas immediately adjacent said arc.

non-conductive material co-axial with and in end-to-end threaded engagement within a chamber said insert, the latter being bored to form a seat each at one end, respectively, to said insert and at their'other ends to said conductive leader, said wires extending through said constricted passageway, and means operative-in response to an arc resulting from the severance oi said fuse wire for releasing saidgas immediately adjacent said arc.

14. A fuse cartridge constituting a replaceable componentv of a fuse-link and comprising: agasfilled capsule, aA conductive sleeve bored lengthwise to form a chamber for'the reception of said capsule, a disc secured in one end of said bore and in pressing engagement with one end of said capsule, a metal insert removably seated within said sleeve remotely from said disc and forming one terminus of said chamber, said insert being bored to form a seat for said capsule and to form a passageway through which the other end of said capsule projects, a tube of non-conductive material co-axial with and in end-to-end threaded engagement with said sleeve, and detachable therefrom, said insert being clamped in place by said sleeve and tube conjointly, means within said tube defining a constricted passageway in direct communication with said other end of said capsule, a conductive leader, a fuse wire and a strain wire, said wires being connected each at one end, respectively, to said insert and at their other ends to said conductive leader, said wires extending through said constricted passageway, and

means operative in response to an arc resulting from the severance of said fuse wire for releasing said gas immediately adjacent said arc.

15. A refill fuse link -unit for fuse cartridges, said unit comprising a metal sleeve having terminal connecting means at one end, an insulating sleeve secured to and projecting from the other end of said metal sleeve, the end of said insulating sleeve remote from said metal sleeve being open, a receptacle in said metal sleeve containing 'a fluid under pressure and having a destructible seal in said insulating sleeve for releasing said fluid, means retaining said receptacle in said metal sleeve, a fusible section electrically connected at one end to said metal sleeve and positioned in said insulating sleeve, a flexible leader connected with .the other end of said fusible section and projecting from the open end of said insulating sleeve, andmeans operative in response to an arc resulting from the severance of said fusible section for destroying said seal and releasing said fluid.

16. A refill fuse link unit for fuse cartridges, said unit comprising a metal sleeve having terminal connecting means at one end, an insulating sleeve secured to and projecting from the other end of said metal sleeve, said insulating sleeve being open at its end remote from said metal sleeve and having a nozzle like constriction flaring toward said open end, a receptacle in said metal sleeve containing a iiuid under pressure and having a destructible seal adjacent said nozzle like constriction, a fusible section electrically connected at one end to said metal sleeve and projecting through said constriction, a terminal connecting conductor projecting from said open end and secured to the other end of said fusible section, and means operative in response to an arc resulting from the severance of said fusible section for destroying said seal and releasing said fluid.

17. An arc extinguishing unit comprising a metal sleeve having a terminal connecting means at one end, an insulating sleeve secured to and projecting from the other end of said metal sleeve, a receptacle in said metal sleeve containing a fluid under pressure and having a destructible seal in said insulating sleeve for releasing said fluid, means retaining said receptacle in said metal sleeve, and conductor means extending from said` open end for establishing an arc to said destructible seal on the occurrence of an abnormal condition in an electric line to which said unit may be connected.

i8. An arc extinguishing unit comprising a metal sleeve having terminal connecting means at one end, an insulating sleeve secured to and projecting from the other end of said metal sleeve, said insulating sleeve being open at its endy remote from said metal sleeve and having a nozzle-like constriction flared toward said open end, a receptacle in said metal sleeve containing a fluid under pressure and having a destructible seal adjacent said nozzle-like constriction, and conductor means extending from said open end for establishing an arc to said destructible seal on the occurrence of an abnormal condition in an electric line to which said unit may be connected.

19. In a fuse, a cylindrical receptacle containtaining arc-extinguishing fluid under pressure, said receptacle having a neck portion of reduced diameter at one end, the terminus of said neck portion being closed by means of a closure member or" thin sheet metal, the exposed diameter of which is less than the outside diameter of said neck portion, a nozzle member oi non-conductive material having a recess for the reception of said neck portion and a passageway co-axial with said recess and terminated at one end by said closure member, said passageway having a diameter not materially greater than the exposed diameter oi said closure member, and a fusible member extending axially through said passageway and operative, on blowing, to strike an arc within said passageway adjacent said closure member, the arrangement being such that the arc will impinge upon said closure member in preference to other parts of said receptacle, thereby ensuring that said closure member will be quickly punctured.

20. In a fuse, a nozzle member of non-conductive material having a passageway therethrough, a receptacle containing arc-extinguishing gas under pressure, said receptacle having a discharge port which is normally closed by a closure member of conductive material which is capable oi being quickly punctured by an arc impinging thereon, said passageway being terminated at one end by said closure member, said passageway being of a diameter, immediately adjacent said closure, not materially greater than the exposed diameter of said closure member, and fusible means capable of producing an arc within said passageway, the arrangement being such that said closure member will function as one electrode of said are immediately after the' arc is established.

21. An arc extinguishing unit comprising a metal sleeve having a terminal connecting at one end, an insulating sleeve secured to and projecting from the other end of said metal sleeve, a receptacle in said metal sleeve containing a fluid under pressure and having a destructible electrically conductive seal in said insulating sleeve for releasing said fluid, and a bored metal insert retaining said receptacle in said metal sleeve, in combination with a conductor including a fusible section adjacent the seal extending from said ,insert through the open end of said insulating 11 sleeve for establishing an arc to said destructible seal on the occurrence of an abnormal condition in an electric line to which said unit may be connected. WILLIAM D. KYLE, JR. ANTHONY VAN RYAN.

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

UNITED STATES PATENTS Name Date Eveleth Mar. 20, 1906 Number Number Number

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