US2662138A - Circuit interrupter housing - Google Patents

Description

Dec. 8, 1953 s. l. LINDELL ET AL CIRCUIT INTERRUPTER HOUSING 3 Sheets-Sheet l Filed March 30, 1951 mi? YU.

INVENTORS. ande@ Dec. 8, 1953 S. l. LINDELL ET AL CIRCUIT INTERRUPTER HOUSING Filed MarCh 30, 1951 3 Sheets-Sheet 2 INVENTORS.

CIRCUIT INTERRUPTER HOUSING Patented Dec. 8, 1953 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER HOUSING Sigurd I. Lindell, Chicago, and Charles H. Baker,

Maywood, Ill., assignors to S & C Electric Company, Chicago, 1.1L, a corporation of Delaware Application March 30, 1951, Serial No. 218,448 9 Claims. v(Cl. 20.0.1120) Tlhis invention relates, generally, to circuit init is desired to increase the resistance of the outer terrupters, and it has particular relation to yhoustube formed oi the materials above noted to ings for high voltage circuit interrupters. it coninternal pressure, a liner in the form of a vulstitutes an improvement over the circuit intercanizeel fibre tube or other tough material is lorupter housings disclosed in application Serial 5 cated within the former and the solid arc ex- No. 273,538, iileii February 2'?, 1952 and in aptinguishing material, such as boric acid, is posiplication Serial No. filed May 28, 1949, tioned therein.

now Patent No. 2,5S9,i87, granted June 3, 1952, is set forth in application Seria-1 No. 273,638, all to the assignee of this application. the granular solid arc extinguishing material is The tubular Yhousings for circuit inter- 1U compacted into a grooved inner surface of the rupters sl'loivn in these applications are subjected tubular hous'ng or into such a surface of the to relatively high open circuit voltages after an libre liner. The purpose of this is to increase are has been drawn therein and extinguished. the creepage and striking distance over the outer Where the normal frequency voltage impressed Surface of the llils of solid arc extinguishing across the tubular housing` is of the order of sevl materia-l at the junction between it and the aderal thousand volts, for example 69 and jacent surface of the housing and to insure that Where the Hmmm frequency Voltage may be 9X- the arc will not restrike here. When a liner of ceedefi to a great extent by transient voltages ble or other material of suitable physical proparising from various sources, diiculty has been erbes iS omployd to provide the desired resistencountered particularly in high current capac- 20 anc@ to internal pressure, diiiiculty has been enity iuterrupters employing nigh strength liners countered 1n producing a Solid homogeneous within the insulating housing in making certain Outer housing Wall and satisfactory bonding be* that any regnition or restriking of the are Will til/'GSH it and lille libre llYleCl 130 DTSVGD reignitale place only in the bore Where it is originally lOn 01 Testflklng 0f the IC alOYle' the junction drawn extinguished a: #l Where it can be sub- 2 therebetween 01' through longitudinal voids in jected to the arc extinguishing action of a gas or the tubular hOuSrlg itself. This llas been pof- Water vapor evolving medium such as vboric acid CUlTlY ilue Where the wall thickness of the m. magnesium homie. lammated tube formed of rolled paper and phen Consel-mgm@ ik@ circuit interrupt@ housings nolic condensation product has a thickness above just mentioned there is employed an outer tube e that is weather has little tendency to inch, for example 1/2 inch to inch, and Where the thickness of the libre liner is about 1/4 inch.

perla-it leakage paths over its external surface, FOY the lf-loSOllS pointed out in application Sebas goed galega-C quali'ies, and is Capable of rial No. 273,633, the nbre liner has a length about withstanding severe lectric stresses. However, equal t0 half that 0f the tubulin' housing and iS this outer tube mechanically is relatively weak 10C-ated midway 'between its ends. For certain and unable under all operatingI conditions to Villtaes a tube length 0f Ovol four feet is required withstand the high internal pressures and other with an external lamelle? Gf three lnclla Such mechanical forces that are incident to the oplllll-SS were mafie by Killing Doper impregnated on or" high current circuit iuterrupters. The llll illlelOlC eSIl loyer on layer onto a nbre rua erials preferably used for making these outer 40 11H91" undel' pl 855111" e @und thm baking il en Oven WMS arg mue@ laminated paper tubes mpreg to cure the resin. For the Wall thickness required nate-rl th phenolic condensation products, ll? W25 found impractical to follow this procemela-ruine resins, porcelain, etc. dule- Due to the reslliencycf the liner uniform In order to furnish the necessary arc extin- Dl'SSuTe @Ould 110i? b2 mamie-ined during the finishing characteristics there is provided Within such tube a material which is capable of evolving a 1mg@ quantity of water Vapor or other are junction with the fibre liner was unsatisfactory. when subjected to the heat ef Gas o1 air rockets were present in a high percentthe Sonie materials which are satisfactory age Of assemblies which caused the dielectric ici' this purpose are corio acid and magnesium 50 Structure t0 l0@ YlOlUnfOlm and DFOVded a path berate, these being granular in character, and where breakdown could occur under severe over- ,M manufacturing process. As a result there was a here. er vuieemzed here either in tubular voltage Conditions rather than resin-kine through s l Sustaining-@1m or asasraekcfrings. These the bore where the arc could be extinguished i terials are arranger?, to provide a bere within readily- ThBSe dllfilltles Bocesitated elaborate i i the are is dra-yu and extinguished. Where 55 test procedures in manufacturing accompanied tendency for the tube to ldelaminate and the` t to the upper end of which one end of a iiexible conductor 40 is connected. The other end of the flexible conductor 4t is connected by a conducting strap el to the tubular terminal as shown at the top of Figure 1B. The purese or the flexible conductor 49 and conducting trap il is to provide a metallic conducting path between the eiftensicn 3s of the rod-like terminal le and the tubular terminal SS after the cylindrical contact section 33 moves out of engagement with the contact iingers l. The ilexible conductor is trained over a pulley 4E which is carried by a yoke 43 that is supported by an end ring 44 carried by the upper end of a compression tube 45. The compression tube is slidabiy mounted in the upper end of the metallic tube and is urged upwardly by a coil compression spring t for the purpose of retractinr,r the rod-like terminal it through the bore it? in the filling il of solid arc extinguishing material when the strain wire and the fusible element 23 have been melted as a result of the flow therethrough of overload or short circuit current.

As pointed out hereinbefore, difiiculty has been encountered in fabricating the tubular insulating housing le with the fibre liner iii therein. in imperfect bond at the junction therebetween btained in a high percentage of the manusseniblies and there was a tendency for on of the layers of impregnated paper rolled under pressure to raalte up the tubular insulating housing Id due to the resiliency of the liner onto which the laminated tub-e was .lis a result there were numerous instances of voltage breakdown in manufacturing tests between the iibre liner i5 and the tubular insulating housing Ill at the junction therebetween or along adjacent layers of the impregnated paper nialring up the housing lll.

In accordance with the present invention as illustrated in Figure 2, these diiculties are overcome by fabricating separately the tubular sulating housing i4 of a phenolic condensation product. rEhis maires it possible to provide the desired wall thicriess by winding the layers of impregnated paper onto a rigid steel mandrel which extends throughout the entire length of the finished housing Iii. Thereafter it is cured to polymerize the resin and to nx the insulating and other desirable characteristics as may be desired. The housing ifi then provided with an internally annularly or circumferentially grooved surface as indicated at preferably by cutting a thread therein. For exemple, in the particular embodiment illustrated where the outside diameter of the housing I i is two and Liinches the thread is a one and sa inches-8 Class l thread.

As illustrated. more clearly in Figure 3 the liner is provided with an externally annularly or circumferentially grooved surface El which is formed by cutting a like thread on its outer surface. Also prior to assembly of the iibre liner i5 in the housing M the internal threads I5 are cut. rihe end sections 5!! and 55 of the threads it? may be cut to a slightly greater pitch diameter for receiving the tubular terminals 2" and 37. Further there is provided an Unthreaded section 5S for receiving the exhaust ring 2s.

While the nbre liner l5 constructed as shown in Figure 3 can be threaded into the grooved surface Fili of the housing I4 lwithout applying anything to the grooved surfaces, it is preferable to apply thereto an adhesive coating. For this purpose the grooved surface 5e has an adhesive coating, as indicated at 5i, applied thereto and likewise an adhesive coating as indicated at 58 is applied to the grooved surface El of the libre liner l5. This adhesive is formed preferably of water soluble urea resin which polynie'rlaes without substantial change in volume. minediately after the application of the adhesive coatings 5'! and 51.3 to the grooved surfaces and El, the fibre liner it is threaded into the insulating housing l so as to provide the composite tubular construction illustrated in Figure 1B. Thereafter the composite housing is baked to hasten polymerization of the adhesive.

By employing the intertting annularly grocved surfaces 5t and iii the creepage and striking .distance over the iibre liner I5 is substantially increased. For example, it may be increased as much as 50% to 100% over the original creepage or striking distance. The adhesive coatings 57 and 'iid ll any voids which might otherwise exist along the boundary between the grooved surfaces and bonds the two members into an integrai structure. After being baked tests have shown that the boundary between the grooved surfaces 5o and E! has a dielectric strength equal to air of twice the linear istance along the boundary off the adjacent materials between their ends. As indicated the threads forming the grooved surfaces Sil and 5| :Sor the housing Iii and fibre liner i5 are formed by matching threads. These threads can be modified so that they have an interference iit thus mechanically pr vide for filling the spaces between adjacent threads when the nbre liner l ti is threaded into position under the required pressure.

In Figure 4 of the drawings there is illustrated, generally at 60, a circuit interrupter of the separable contact type. The circuit interrupter 6&3 includes an upper line terminal ci and a lower line terminal t2 in the forro of a housing which is employed for enclosing an operating mechanism that is indicated, generally, at Between the line terminals el and e2 there is provided an insulating housing, shown generally at t4, which comprises a suitable ceramic material such as a tubular porcelain insulating housing having therewithin and coextensive therewith a liner 65 formed of vulcanized fibre or horn fiber. The porcelain housing t5 is provided with a grooved inner surface 'l which is formed by cutting a thread therein prior to the curing of the housing 65. Likewise the outer surface of the nbre liner t6 is grooved as indicated at E58 by a suitable cutting tool.

Prior to threading the fibre liner into the porcelain housing 65, the former is enclosed in a sleeve 69 that is formed preferably of synthetic rubber and has sufficient body to fill the spaces between the threads in the grooved surfaces 67 and t8 when the rlbre liner et is threaded into the porcelain housing- 65. in order to facilitate the entry of the fibre liner G53 with the synthetic rubber sleeve thereover, the outer surface of the latter can be provided with a suitable lubricant such as talc or the like.

At its lower end the nbre liner et is arranged to receive an extension from the line terminal housing 62 and the saine is provided with threads 1I to iiX the same in position. The fibre liner 65 has a bore 12 extending therethrough in which the arc is drawn and extinguished and through which a rod-like terminal 73 is movable by the operating mechanism 53.

At its upper end the rod-like terminal 'I3 has Contact lingers 'lll which engage a Contact sleeve 'l5 that is threaded at l5 into the upper end of the fibre liner SB. The contact sleeve l5 is threaded intermedate its ends at 11 for threaded engagement with the line terminal Si at the end of the insulating housing te. An insulating trailer i8 is movable with the rod-like terminal 63 into the bore l2 of the libre liner E5 for the purpose of confining the are between its outer surface and this bore when it drawn between the contact lingers 'M and the contact sleeve 1E.

Since certain further changes can be made in the foregoing constructions and different embodiments o the invention can be niade without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. In high 'voltage circuit interruptor, in combination, an tube having a length several tiines its diameter and having a threaded inner surface over a length several times its diu arneter, line terminals at the ends of said tube, a one-piece tubular self-sustaining liner having a length several times its diameter and having a threaded outer surface threaded into said tube, the space occupied by liner and said tube coextensive therewith being free from voids and no path being provided therebetween along which current can flow or an are is likely to be struck, stationary conducting ineans extending from each line terminal into said tube for a substantial distance with the inner end of each conducting means projecting into the correspond-- ing end of said liner, and means interconnecting said conducting means ior drawing aro within said tube and liner on operation of the interruptor, the break distance between the terminals of said are drawing means in the circuit open position being less 'than length of the juxtaposed threaded surfaces oi said tube and liner.

2. In a high voltage circuit interrupter, in coinbination, an insulating tube having a length several times its diameter and having a threaded inner suri'aee over a length several times its diameter, line terminals at the ends of said tube, a onepiece tubular -sustaining liner having a length several times its diameter and having a threaded outer surface threaded into said tube, the space occupied by said liner and said tube coextensive therewith free from voids and` no path being provided therebetween along which current can flow or an are is likely to be struck., stationary conducting means extending from each line terminal into tube for a substantial distance with the inner end of each conducting means projecting into the corresponding end of said liner, said liner having an annularly grooved inner surface, a filling of are extinguishing material compacted into said grooved inner surface and having a bore from the surface of which an are extinguishing medium can be evolved due to the heat of the are, and means interconnecting said conducting means for drawing an arc within said bore on operation of the interruptor, the breal: distance between the terminals of said arc drawing means in the circuit open position being less than the length oi' the juxtaposed threaded surfaces oi tube and liner, said conducting means acting to distribute voltage stress applied to said line terminals to prevent arcing therebetween externally of said tube and applying the fill - struck, a st voltage stress to the ends said juxtaposed threaded surfaces and the ends of the juxtaposed surfaces of said liner said filling of eX" tinguishing material whe A by any strucl; between conducting means formed and extinguished in said bore.

3. The invention, as set in the insulating is a product and the liner is iorinei o bre.

ll. rlhe invention, as set iori4 claim l, where in the insulating tub is fornire-d of porcelain and the liner is formed o- 5. The invention, as set io in a layer oi insulating polJ eed adhesive niaterial whose voluine r ns substantially constant alter polymerization interposed between the juxtaposed threaded surfaces oi the tube and liner.

6. The invention, as set forth in clainl l, ivhere in a layer of Water soluble urea resini nterposed between the juxtap sed 'threaded su tube and liner.

'7. The invention, in a layer oi synth 1c r tween the juxtaposed thi tube and liner.

Si. ln a high voltage circ 1' bnation, an insulating tube having a length several tiines its having its inner suriace midway over a length egual to hall' thl` in claim l, where olie condensation nds t e length oi the tube, line terminals at the ol tube, one-pieee tubular self-sustaining liner equal tube, the space occupied by liner and said tube eooitensive therevvitl hre from voids and no tl being prov veen along wh. h current can f o, an are is likely to be 'uct-or extending ^d tube and into `l liner, and means r conductors for drawiroin une terminal ti e pending end o' ereonnectings nig an are within said l tion oi the intel A tween tl terminals oi saL in the circuit open po,n .ion being leW than the length oi" said liner.

ln a high circuit .interrupt-er, in coinbination, an insulat` ig tube h face i.. dway its threaded ov r a length equal to half length of the tube, line terr at the ends said tube, a one .bolar selisustaining liner equal e length no path being provided tl. ereb current can ilo'iv or an are iU be struck, a stationary tubular eonouotor 'ending from each line terminal into said tube and the corresponding er, an. annularly gros ved extinguir-shi l! ,i along which ze, :.ii

into

l@ ETC, n c

conductors d applysaid juxta- References Cited in the 111e of this patent UNITED STATES PATENTS Number Name Date 2,073,565 Ruppel Mar. 9, 1937 Number 10 Name Date Rawlins et a1 Jan. 19, 1943 Triplett May 18, 1943 McMahon July 27, 1943 McMahon Sept. 7, 1943 Rawlins et a1 Sept. 11, 1951 Fahnoe Sept. 11, 1951

Images