Document Ex2L7GdkL21grkjoV3NJnENn

FILE NAME: McGraw-Edison (ME) DATE: 1989 Jan 31 DOC#: ME021 DOCUMENT DESCRIPTION: Patent [Cooper] - Asbestos free material for gassing current limiting fuses [Approved - 1990 Aug 14] United States Patent [19] Johnson et al. [54] ASBESTOS FREE MATERIAL FOR GASSING CURRENT LIMITING FUSES [75] Inventors: Stephen P. Johnson, Olean, N.Y.; Stephen P. Hassler, Muskego, Wis. [73] Assignee: TCeoxo.per Industries, Inc., Houston, [21] Appl. No.: 304,731 [22] Filed: Jan, 31,1989 [51] Int. CI.5 ............................ C08K 3/34; C08K 3/22 [52] U.S. Q ..................................-....... 524/437; 552244/4/55967; [58] Field of Search.....1..7..4.../.D...I..G.......1;250204/1/44347C, 4, 5164,95A97; [ii] Patent Number: 4,948,828 [45] Date of Patent: Aug. 14,1990 [56] References Cited U.S. PATENT DOCUMENTS 2,596,134 5/1952 D o rs t....................................... 524/597 2,917,607 12/1959 S terlin g .................................. 524/597 3,242,257 3/1966 Jones et al............................... 524/437 APtrtiomrnareyy,EAxgaemnti,neorr--FLiremw--isDTa.vJidacAob. sRose [57] ABSTRACT Aasbsepsitdoesrffroere amgaatsesriinagl icsudrirsecnlot sleimd.itTinhgefuspseidmeradmeatoefriaanl bpryoadnucaersc.aTn haercmqauteenricahl iinngclguadseasntdhewfaotlelrowupinogn perroopsioorn tions of ingredients: 50-80% AI2O3.3H2O; 8-22% Wol- lastonite (CaSi03); and 10-25% melamine formalde hyde resin. 9 Claims, 2 Drawing Sheets U S . Patent Aug. i4, 1990 sheet i of 2 4,948,828 FIG. 2 FIG. 4 U .S. Patent Aug. i4 , 1990 Sheet 2 of2 4,948,828 126 1 4,948,828 2 or finely divided quartz which forms a fulgurate when ASBESTCOUSRFRREENETMLAIMTEITRIINAGL FFOUSREGSASSING exposed to an arc and further aids in limiting the cur rent. FIELD OF THE INVENTION The spider in gassing fuses is conventionally formed 5 of an asbestos-containing material. The problems with useThaes itnhveengtaiso-nemreitlatitnegs tmo eamnbaesrbeisntoas fcruereremnattelirmiailtifnogr the use of asbestos are well-known. Asbestos fibers and dust are a significant health hazard, and can cause, gassing fuse. among others, the conditions known as asbestosis and mesothelioma. Asbestos dust can be generated both BACKGROUND OF THE INVENTION 10 during manufacture and during disposal of conventional is Isnurarocounnvdeendtiboynaal cgurarrneunlatrliminietrintgmfuatseer,iaalfuosfeheliegmh ednit gassing spiders. Due to worker injury, significant liabil ity for both manufacturers and disposers of asbestos electric strength, such as sand or finely divided quartz. The fuse element is typically wound onto a support products has become common-place. Accordingly, elimination of asbestos from gassing fuses is desirable. core, or spider. When the element is subjected to a 15 Thus, what is needed is a spider material which is ccuurrrreenntt orefsfualutsl.tTmhaegnmiteutadleaannddthvaepmoreitzaelsv, aaprocrinsgexopfatnhde aqsubeensctohsthfereaer,c.but which nevertheless functions to into the spaces between the inert material. Contact between the hot arc and the relatively cool granules SUMMARY OF THE INVENTION cpaautessesthaeheaartctreannesrfgeyr fbroumt caarucsetos gvrearnyulleitst.leThpirsedssiussrie 20 The which present invention includes a spider material is asbestos free, and yet is well-suited for use in breusiuldltuspfrwomithtihnethvaepfoursiezatsitornucotufrteh. eAfuhseigehlemreesnistt,anthcee ccuiarlrlyenutsleifmulitiinnglogwassfainuglt fcuusrerse.nAt agpapslsicinagtiofnuss.eTisheessppei removal of metal vapors from the arc path, and the rapid cooling of the arc. The current is limited accord 25 der material is made up of AI2O3.3H2O, CaSi03 (known as "Wollastonite"), and melamine formaldehyde resin. ingTlyh.e resistance increases rapidly. The sand particles in The spider material preferably includes the ingredients in the following-range of proportions: cthloesheipgrhotxeimmpiteyratotutrheeoafrcthbeeacorcm. eHpoawrteivael rc,onfudsuecdtoprasrtait cles cool on extinction of the arc and solidify into a 30 fulgurate, which is similar to a glass body and is an 580--2820%% WAIo2lOla3s.t3oHn2itOe; and insulator. 10-25% melamine formaldehyde resin. cesIsnoofrpdreerdteoteirnmsuinreedagliaminitsst, sthuregfeusveoeltleamgeenpteamkasyinhaevxe A preferred embodiment has the following propor a variable cross sectional area. It has areas of reduced 35 tions of ingredients: cross sectional area between areas of large cross section. This arrangement can be accomplished by, for example, punching a series of circular perforations in a ribbon 7102%% WAIo2lOla3s.t3oHn2itOe; and fruesdeu.cTedhecreodsgsesseoctfiothne. pTehrefoseraatiroenass foofrmredthueceadrecarsoossf 40 18% melamine formaldehyde resin. section cause progressive insertion of arc resistance into the circuit. In turn, this keeps the rate of current change The spider material of the present invention is used to rtievleatisvuerlgyelovwol.tAagseawrehsiuclht, mthaisyteoncdcsurtowlihmeint tahecuinrdreunct sguepnperoartteas afunsearecleqmueenntc,hainngd gwahseans cwoenltlaacstewdabteyr.aInt acracn, lciimrciutiintginfsuusleatoiopne.rates, which otherwise might damage 45 be used for all the same purposes as a conventional asbestos-containing arcquenching material, but does not A gassing current limiting fuse is an improvement over that described above. In such a gassing fuse, the suffer from the health-related problems associated with asbestos use. sthpeidperorwtihoincshosfupthpeorstpsidthere mwahiinchfucsoenetlaecmtetnhte, omraaint lfeuasset 50 apOpetahrerfroobmjetchtes faonldlowadinvgandteasgcersipotifotnh.e invention will eqlueemnecnhti,nagrgeams awdheeonf caomntaatcetreiadl awnhdicehrogdeenderbaytetshaenhaeract BRIEF DESCRIPTION OF THE DRAWINGS from an arc. Such materials include, for example, molded thermosetting compositions which include a For a detailed description of a preferred embodiment of the invention, reference will now be made to the wsuactherasinhsyodlruabtlees boirnodxeirdeasnodfaanlumanintiu-tmraacnkdinmg asgunbesstaiunmce. 55 accFoImGp. a1niysinagsiddreawviienwgs, pwahretriaelilny: in cross section, of a Tplhee, mmiactae,rigallascsa,nfiablesro, ianscbluesdteosvaorriosuiliscfoinll.erOs,nfeorsueixtaabmle current limiting fuse utilizing the spider material of the present invention; material comprises about 75 percent aluminum hydrate filler, 20 percent polyester resin, and 5 percent glass 60 FIG. current 2 is a side view of a spider subassembly limiting fuse shown in FIG. 1; of the fiber. See U.S. Pat. No. 3,294,936 at col. 3, lines 43 et seq. subFaIsGse.m3bislyaspheorwspneicntivFeIGvi.e2w; of one end of the spider The gas which is generated upon erosion by the arc cools the decaying fuse element and fulgurate, and also FIG. 4 is a view of one end of the fuse shown in FIG. 1; and provides a high resistance to further current flow. In this manner high current flow which could damage the 65 FIG. 5 is a longitudinal cross sectional view of an other current limiting fuse in which the-spider material cviernctuioitniasl. ifmuspee,dtehde, faunsde heeleamt eisntdiisssispuartreodu.nAdesdinbya scaonnd of the present invention can be advantageously em ployed. 3 4,948,828 4 DESCRIPTION OF THE PREFERRED EMBODIMENTS preferred shape for the spider 10, suitable for use in a gassing fuse, is shown in the accompanying drawings Referring initially to FIG. 1, there is shown one em and described above. The embodiment of spider 10 shown in FIGS. 1 to 4 binocdluimdeedntthoefraeingaasssinpgidecrur1r0enmt alidmeitoinf gthfeusaesb2e1sthosavfirnege 5 is suitable for use with the preferred gassing, current limiting fuse 21 of the present invention. Conducting mmaatinerfiualseoefletmheenptr2e0sewntraipnpveendtaiornou. nFdutshee2s1pidinecrlu1d0easnda end caps 68, 70 at opposite ends of fuse 21 include ele ment terminations 22 having tabs 74 and 76. Tabs 76 are housed within a fuse tube 82. Conducting end caps 68, 70 are fitted over the ends of tube 82 to encapsulate fuse 10 affixed to extending raised shoulders 18 at end of spider 10 by over the shoulders 18 and surrounding them ealfefimxeedntto20eaacnhdesnpdidcearp1608,th7e0rreewsipthecinti.vSetlyudfosr8c3o, n8d5uacrte ing current through the fuse 21. ofinrmtlwy oto seiadcehs. eTndhios fasrpridanerge1m0.enTtabfsas7te4nosneelleemmeenntt 2222 Referring four radially now to FIGS. 2 and 3, the protruding fins 14. Each fin s1p4iad,er141b0, has 14c and 14d includes a series o f alternating depressions 16a, 15 mate with a recessed portion in the end wall of each of tiehnetemndoucnatpisng68o, f70sp. iTdehris1a0rrwaintgheinmetnhtepfruosveidtuebsea 8r2esoilf 16b, 16c and 16d (the latter not shown), respectively, which extend longitudinally on each fin 14. Each pair of fuse 21. In fuse 21, main fuse element 20 is spirally wound sduecrsce1s8sivone deeapcrhesfisnio. ns 16 forms a series of raised shoul around raised shoulders 18, and each end of element 20 is connected to a termination element 22 (as shown in besDtespeernesisnioFnIsG1.63a, rdeesptraegsgseiorned16aaloonngftinhe14spaiidseerle1v0a. tAeds 20 FIG. 3). Fuse element 20 includes two spots 90,92 made of a low melting temperature alloy such as tin-lead from depression 16b on fin 14b, which in turn is elevated from depression 16c on fin 14c, such elevations being solder. Fuse 10 is connected with a circuit through studs 83 and 85. Current flows from the stud 85 to the measured from the central axis of the fuse 21. The de pressions 16 and raised shoulders 18 define a continuous 25 conducting end caps 68, through tabs 74 and to element termination 22. Main fuse element 20 is connected with heTlichael pasabthesftoors tfhreeemsapiindefursme aelteemriaelntfo2r0.the spider 10 element termination 22. The same arrangement of ele ments is present at the opposite end of fuse 21. (inCcalSuidOess), tahned mineglaremdiineentfsormAIa2lOde3h.3yHde2Ore,sinW. Tolhlaisstmonaittee 30 Referring again to FIG. 2, fuse 21 also includes an auxiliary fuse element which has two wires 46 spirally rtiioanl aisl gsuaistsainbgleffuosre amnaytearpiaplliccaantiobne einmwplhoiycehd.a conven wound around the depressions 16 of spider 10. The ends of wire 46 are connected to respective air gap elec To make the spider material of the invention, the foregoing ingredients are mixed and a small amount of trodes 40. Between fuse element 20 and air gap elec trodes 40 is an air gap of predetermined size. One side of Tacheetriceafatceird, t(hliesssmitxhtaunre1is%p)aciskeaddidnetdo,awmitohldbhleanvdiningga. 35 tdhuectaiunxgileianrdycfaupse6e8l,etmhreonutgwhirweisr4e65i0s acnodnnveecnttedintdoiccaotonr dtheesnireadirshdarpieed..LAaitrerd, rityiinsgrefmorovaepdefrrioomd othfe24mohlodu,rasnids wire 62. Referring now to FIG. 3, fuse 21 includes a wire pprreeffeerrraebdly. Ttohebemtwoeldenan2d00t'h-3e0m0ixFtu.,reanadremthoestnphreeafeterda, 40 assembly 48. Assembly 48 has a wire 50 which is threaded through a passage 56 extending from the axial bhlayvetoth2e40d'esFir.,edansdhadprei.ed. The dried mixture will now ceernytoerf sopfidoenre1e0n,danodf sspeicduerred10totoana epyoeinletto5n2tohfeepleemripenht The proportions of the ingredients in the final dry mixture can range as follows: termination 22. Wire 50 is then spirally wound around spider 10 in the helical path defined by the depressions 50-80% AI2O3JH2O; 45 i1s6,naeanrdeestletcotroicpaelnlyincgon58neacntdedetyoeltehte5e2l.ectrode 40 which 180--2225%% Wmeollalmasitnoeniftoer;maanlddehyde resin. Referring now to FIG. 4, at this same end of fuse 21 is a vent indicator wire assembly. A vent wire 62 of high resistance material, for example tungsten or nichrome, Afolplorwefienrgredpreompobrotdioimnsenotfoinf gthreedsipenidtserinmathteerifailnahlasmtihxe- 50 is connected to an eyelet which is in the center of the end of fuse 21. This eyelet is connected with eyelet 52 of ture: tphaessaaugxeili6a6ryinwitrheeacssoenmdbulcyti4n8g. Wenidrec6a2pex6t8e,nadnsdthtrooutghhe 7102%% AWIo2l0la3s.t3oHn2it0e;; and outside of fuse 21. Wire 62 is soldered to a point 63 on 55 the outside of the conducting end cap 68. 18% melamine formaldehyde resin. Fuse tube 82 is filled with sand or finely divided quartz. Optionally, an elastomeric gasket can be fitted Arianl ahlatesrtnhaetefoplrloefwerinregdpermopboordtiimonesntofoifntghreedspieidnetsr imnatthee on the ends of tube 82, and end caps 68 and 70 can be fitted over the gasket. The end caps and gaskets can be final mixture: 60 sealed with epoxy to provide an air and water-tight seal. Optionally, second end caps (not shown) can be fitted over conducting end caps 68 and 70. The second end 6155%% AWIo2l0la3s.t3oHn2it0e;; and caps compress the gasket (if present) and produce a water-tight seal between the ends of the second end 20% melamine formaldehyde resin. 65 caps and tube 82. The shape of the mold, and thus of the spider 10, can paTrths eismaenxnpelarinoefdassinemmbloinreg fduesteai1l0inandUi.tSs. rePsapt.ectNivoe. vary depending on the intended use for the material. A 4,150,353, incorporated herein by reference. 5 4,948,828 6 In operation, a fault current will open the fuse ele main element 138. The current passes through main fuse ment 20 at two spots 90 and 92, which are preferably element 138 to element 117, which is connected to the made of a low melting temperature alloy such as tinlead solder. The voltage of the arc across the open circuit. Although the spider material of the invention has section of the main fuse element 20 will also develop the air gap between the other end of auxiliary fuse wires 46 5 been described as useful with fuse embodiments 21 and 110, it can also be used with virtually any other type of and the main element 20. The arc voltage will increase as the length of the arc increases, eventually causing the gassing fuse. In addition, the spider material can be used anywhere that arc-tracking resistance is needed. These atoirfgoarpceatctuhrereunntcfolnonwecttoedtheendauoxfilaiaurxyiliianrdyicfautsoerwciirrecsu4it6, 10 uses include utilization in high voltage devices as substi tute, or a cover over, materials which can track an arc. whCicuhrrceonntsfilsotws othf rwoiurgehs 4th6eahnidghvernestisintadniccaetworirwe i6r2ew62il.l Because the spider material evolves gas and water in response to an arc, it will quench an arc in any of these cause wire 62 to vaporize, providing indication that the fuse has operated. Upon vaporization of wire 62, cur situations. It should be understood that the terms and embodi rneantitofnloowf rweitruern6s2toonthtehme aoiuntfsuidsee eolfemseecnotn2d0.eAndn ceaxapm7i8 can be used to indicate whether fuse 21 is operating 15 ments described above are exemplary only and not limiting, and that the scope of protection is limited only properly, or has operated. Referring now to FIG. 5, there is shown an alternate by the claims which follow, and includes all equivalents of the subject matter of the claims. fpurseeseenmt binodviemnteinotn.foAr utsuebwuliathr cthaesinspgid1e1r2mfaotreraiacluorfrtehnet 20 What is claimed: . 1. An improved material for a spider of a gassing fuse, lmimatietirniagl fsuusceh 1a1s0gliassscofnibsetrr,ucotredglaosfs sfuibitearbilme pinresuglnaattinedg consisting essentially of the ingredients in substantially the following ranges of proportions: with epoxy resin. A metallic end piece HR may be secured on the right end of casing 112 by means of any 25 suitable seal such as epoxy cement, and a metallic end 50-80% 8-22% AI2O3.3H2O; Wollastonite (CaSiC>3); and pthierecaed1s1nLeamrathyehlaevfteeenxdteornf acal stihnrgea1d1s2etnogaafgfiixngenidntperiencael 10-25% melamine formaldehyde resin. 11L to casing 112. A metallic hinge assembly 114 may be secured to the opposite end piece 11R. The end piece 30 2. The material of claim 1 wherein the proportions of 11L has a portion 115 with an axial bore 116. A tubular ingredients are as follows: mfoertcaellfiict manedmibserrig1i1d7lyesxetceunrdesdintotoeanxdiaplibecoere111L16bwyipthinas 70% AI2O3.3H2O; 118 extending radially through tubular member 117 and portion 115 of end piece 11L. Terminal member 117 is 35 1128%% Wmeollalmasitnoeniftoer;maanlddehyde resin. adapted to fit within a stationary contact jaw (not shown) of an electrical switch, and an insulating mem ber 119 may be secured in the end of tubular member by 3. The material of claim 1 wherein the proportion of ingredients is as follows: sguuiitsahbilneg msleeaenvse 1su20chsliadsabelpyofxitytincgemoevnert. cAasningar1c12exmtiany 40 have an inner tubular portion 121 of insulating material 65% AI2O3.3H2O; telescoped over terminal member 117 and may cover terminal member 117 by a helical spring 122 com 2105%% Wmeollalmasitnoeniftoe;rmanadldehyde resin. porfeassrecdebxettinwgeueinsheinndg pmieecme b1e1rL1a2n0d ftohre etnhde ppourrtpioonse12o4f 45 4. A process for preparing an arc-quenching material, intMerertuapltliicngenadnyplsattreasy1a2r5c.are disposed against the inter comprising: preparing a mixture consisting essentially of the fol nal surface of end pieces 11L and 11R and are secured thereto. Each end piece 125 has a plurality of radially lowing ingredients in the following proportions: emxateynfdoirnmg ttaerbms i1n2a7lsatdojawcehnicthitscoonudteurctpoerrsipmhaeyrybewhcoicnh 50 50-80% AI2O3.3H2O, nmeocutendte. dAwnitehlionncgaastiendg i1n1s2u.laTthinegenspdisdeorf s1p2i8deirs 1a2x8iaalrlye 180--2225%% mwoellalamstionneitfeo,rmaldehyde resin; affixed to end pieces 11R and 11L. ' Spider 128 is of generally star-shaped cross section (as 55 adding water to the mixture and stirring to form a dfiensc1r3ib2edhaasbaovpel)uwraitlhityraodfiadlleyperxetsesniodnisng1f3i3nsa1n3d2.rEaiascehd putty; shoulders 134 as described above. The depressions 133 of peripherally successive fins 132 are progressively molding the putty into a shape desired; stitoanggfeorreda htoelifcoarlmly swuopupnordt cmirecaunits ionftehrerluicpatilncgofnufsigeuerlae 60 heating the putty; and drying the putty. meTnhte1r3e8minatinerdceornonfetchteinfgeatthuereesnodfpfuiescee1s1101aLreasnudbs1t1aRn. 5. The process of claim 4 wherein the water added is tially the same as those described above for fuse 21, and as set forth in U.S. Pat. No. 3,294,936. Fuse 110 is con 65 substantially in the amount of 7% of the mixture. 6. The process of claim 4 wherein the putty is heated nected to a circuit through an eyelet 126 in metallic hinge assembly 114. Assembly 114 is connected with to about 240 F., and is air dried for 24 hours. 7. The process of claim 4 wherein the mixture consists collar 11R, and from there to wire elements 141 and essentially of the following proportion of ingredients: 7 4,948,828 8 70% A1203.3H 20 ; 12% wollastonite; and 18% melamine formaldehyde resin. 6155%% AwIo2lOla3s.t3oHni2teO;; and 5 20% melamine formaldehyde resin. 8. The process of claim 4 wherein the mixture consists 9. claims A product produced 4 through 8. by the process as in one of essentially of the following proportion of ingredients: ***** 10 15 20 25 30 35 40 45 50 55 60 65