1,782,200 3 gii,c-ii ai@eatei- etirviture tlaii, jL- 'iic. f-,-tee 15 oi' thiii tlie ot@@tci- tip of the pole me-mber insije ,.iier.-iber 3, i,-i siieh a qii.1 Pext q.,Jjtcent to it, biit goocl 1-esv,!'Us are 11.11(ic-r c-acli oa': t'@lu-se f@"ces ic's obtlinel wheii ,lie iiiier t"p !-.s iio"L- f a,-tllei-i siiie C-l' 011' closi LI 1,, e val ivive o-l' clis- frcni the pole ceii '.Iiiii ")e o-,)L'-ei- 'il) of l'IDUU10n. the Pext acliaceiit iniiei- I)ole iileliil)e,., @)3, !I-tol,e Meiiiber 24. iihicli serves to sp,,tcc@ coils 6 iiilf of the siitlles'Ll clelrance betweeii -a theiii iii place is ,riacle of no-,I- @llia ilol-. ti Lhe -,ii-iiiattire -,t th,@il P,,)iiit. @,ii@L t pi (1,' u - L,- - v ic' -wit,ii tii,elve po-les a bu. Lv L, slioi, ,t iii, iiine n I o-,@l-ii4,-tecl, i'-' cllisirecl, ivitli ielict c livi-,Iecl ito 'uhree coil@,3 iitye 'LIie recili,-'.site str-e-.-igtli to holo l@lie coils 1)er pole, -ii-%,idiao- -@he, core into -.'lve ill !)lace the iicl o,-' 24. The tiorslbti'L-, L i-s thilu- i-4L, is not li---Zi-t-,d -ieiitr,- tli-2 l@Ine A-A is '6o qiiv nlii)iber of i)oies or an37 rumber of sho-w--i bi, trace it is a i -,,aao@netical.13, iieticoils rle. Tlie modificaliois iieedecl in Pe, PO tr,il plai.e loc,-,tllc't hiltway bet-",eeii oppos,--@- 0 1 ,e a@iv c,,isp, - tr cj,-@qr"v set frrtli i-Ti t'-iie specific,,It)ol-es. Tlio ,)ol,e I,, oL@tie outer membeils tioii is to t-@ei-i@ )-uidiit)@ 1,Ve aim ill o i-o the po'.e tl-,)s 23 @s j?rolo@,igecl tile cla@j:iis to cover ,ii-I modii'lea"ii the )Ole P,,a:r i -. at,-l p q, r 4L, o m, t h e s -i r -i t a n cT !,Ips Ire ), qs cl-os-- 'tions @,do iio'u OLe p to the -Lieu@-r.11 ix-s A--@k as ti-ie.), zi,e Clistfiiit scop-, of inventioii. -Pro@i-i the ariiijture, stirfi,-e 14. '@"lie f@qce I'T Tlle iriiiatiTre sho-wii ;@@-i tl-ie cli-,,,,,,vo'L members 5 n-iav roi@- be laid otit exactly 'iDy is customa.-ilv useet, r@arelv, i'll I the s;li-ri-ple i-,cile ra-o is 4uo vf,-@,@y v7h4 ich the @,1--,i-iature is @,,isposeCL iii -ecl fltix derisita,@ b-,it @t sei-ertl slots I)e-@- I)ole ,)Pr:@)liase, blit any clei@n, -,rsely as the elesij I I - - - silgli'L correctiolli i-, C"esirable wlieii t'@-'ie clesiral)le ariiifL'L--Lij-e be tised iii consireci fltix de-Tisltv ilo--tig the otir inventi@n. 14 i,aries less r,,il)if-Ily th@i-,-i t-@i-ie Oz-'Lsta-,ice fi,olil B-,- @--lie 'Lerin "desired ivtve o-.' flux disoo ulie iieti$'rqi ,txis, ,is is the c,,,se witli ,I s,.,ic ive me,,, n ,L sine wci-%Ie, or oiie -which 'wave pole -F-.ice l@ - a.-,I-ace,,-'@ 'Uo the t-lr) (locs clev;--,'te iL i)oiiit mor,@ 2'D is broiio,ht slight,ly closer 'Lo '@he tli@iii 10@o nor de-,@iate tjjierefrom in such a surf,,tee, ip-cl vice verst. iiian@.icr f,,s to e-guse objectioiiable telepli-one S@.i)-ce t@,,e s,-@ i-,e of flii--,: clensi't,-V,- 'IS !'coo ii-, enft - -@ -,@. iiize(I as the best. the best 0, )Ol-u -v@-e is our iilve@,i" c LIoll IS: is that iii -,vhich t@,.e cli-s4.-ance T---@-om tl,-ie 1. The conibiiiation -witli tl-ie -ri-iiattire of a t Li r e s ii @, f -@ c -, i-,,t r i e s a c c o r ii (,-,, t o t i i I 1- 0 71 - eleclcric macliine, -of a. t-elcl ini(yiiet i,io- eqtiqti-o,-i : Le'@- ttie Oist,,i-ice a clistribule(i n - - - , a 4- rf@ Pidi.,@."i tv of coils for e-,tch poli@ ind i)ol-, iiaeiiiI c n, -,7 1) o-, 1- t -@, P, e cq ii 'I @uire suriac(, bQ X, c,,iicl the 0,;Istin-o t'.1,@i-I bers, e,,icl-i weiiiber oy' +lie pole'so shapecl ivitbI-,oiiit to the ,?oje be Y, on t'@- ,e re-'e@-epee to -its adjoiiiip-- iiaei-iiber tliit airii-ia,yp.e@,-o-ii-iot;.ve T-o,-ce if oi) +lie 'Uivo sicies of at-iy coil separpti,,iu the role co-7.,t-Ir i-s G t,-cl ii-i, -11,@r@i-@i,e !,jjgceiit pole iiieiii.,--,rs are to each otlier -i -,@ e g. 'p -i, crce on t'ii,,,t be F, th,-i 11, -,i) at t,ie i@o,- @L" the ji ig iie'o-iiiotii-e fore s o tl-ie respective INr@ Is fqces of saicl pole n-iembers. F 9-. The. coi-nbiiialu-ioti -wii'b @,lie of i y= C, ( -,, cosecap_t islo!@ clyiiin-io ele,-tric niaciiine, o--F a -lielcl inignet F, J)o hq@- ,,in ,-2,, a clistribtit--,l ivi-iicii-,Ig coilipr;slii"' t -@-he d-sta-,ice froi-ii i-i ',II t,o ,)Itlr@ilitv oT- coils for eacli -,)ole, I)oles. T is b 4 P.e,,itr,-,Il oxis on the c oiilvalqpt qu,,- eich pole co-iiprislpc, PI of _e zn -L,qc,e or fl'iia -,)ole t:,4,- 1)ole face bei-.iQ, incitiditio, OILI+Ier I)OIE r,- ibers. ',-lip cc,-s-pers o-f -L z@, iiie coilrec4-e(-l t 11 r curv,.i.lu,,,re in lie 'ipaes of fol-ce efch o-@Lter pol6 membe,,, -ne,,ti-est tli,e pole L C' 4- ear tlie pole til s. It -kvi-I-I be u@i,,-Iers'a d thft,.' cen@-ei, bei-Tig formeci @6 a re!-,iti-vely Sil'.Irp y ti-ie fbove eqliation ho'@-,-Ils ior 'cbe pol(, T-.Ice u-.,) acutc- aiigle th,,)I'. i-s, an ,iT-igi-e iiot materiill t(@) t]-le ti,,)s; tlia,, Is, qs !on, ,,s )' is le s i e,,iter th,,in 45 0. ,lie di5',,@nce t(" t@ip ;Ilterpolp"@- -Ixis. 3. Tl-,e.combi-Ti,),ti@oii- witli the armatu--ce of,a ri or t@.e bl-st res,,ilits tie ec,,rners -),,, @ips lk@@ d3@r.,,im6 eleetric n-iachine, of -I -'Lielcl iiia-iie't, 20 o,'- pole 4 5 9@r(., mfide Nvitli a (ii-stribiitei -WiTiclipg coilIT)rlsincy a I 'bie, as s, PI,, i t@l-P ',I clirvI,Llll,u, is is ,)Oss--, i P.- @l -c !it of -oi-.Is T-oi-,icji ])Ole, ITI(l ])Ole-q, 1- - y @or.n-ied to 9.n act,@'e in@xle so @tlliit 41-he u,-de7-@ &@,ch 1)oie a. pitir,-Iitv of ilierlastir-Tice,,@ 2C, 97@ 11-o t'@ie slot, ',Irla be-- ,,s, @,@ole tle inell-ilecl I:' aii ai,,u - I T) of elli,-Ch otiter po-e @@e @ie corii,1,3,s at LI' e in,,-ier 'ui- I anc'L aw,-,v from the ceiater of tli-- p-,)Ie@, L"ic beiti,-r le@,@s than 'Llie (yoj) a'-, th,- centl,.l I 1) 1 i,t o'L I n - L best angle beiii _g rot irintei,ig,'."y tl-ie @@ntrall pole meniber. 45 degees. 4. The conabinitio-Ti -wit@- the irDiqttire of i J"or b,-,s'L-1 re,,,tilt's the sio'.- o 1 @ e, el C4 ,O Lric i-iiaeliiiie, of a f-ielci m@i--. ("t be'u-ivee-Li the poles ancl -1- 5 SI-,oill-,i ji,-tvihg a disl-ribtite,-l i7,iiiOj'llg be --@iqrro-w, ,.-,o that @Lhe i--,"p a-- ,i piiirtlit@, of coi-l-s for e,-cli I)ol-,, atcl -j)oje,@3, C.- PO le mei-@iber is iiearer to the center c,@- )c) ieiciipolecomprisiiigaplurilityofn-lei'iibers

in,citid-ing otiter pole nieiilbers the tips of s,,ticlOliter pole D-- .embers negresf, 4,-i-i6 -.,3ole ce-,i'Le,-, 13eing dist,,tnt from the equivpl(@nt ,i,,:mat-Lire sur-Lqc@,. xviieii coT-npareOt witi-i @ul-igep Pt -,,@h-2 ce-.i'Lor 6f the Po!-e. 'In the -,)-.L magneto-mo'uive -Torces on these til)s to the li'la,o-neto-nio.qv.,- @--@Or-ce on the ce-o-ter of @b-c poles:,tll,-! iT-l inv,erse rat,.o of:tl-ie valu,-2 ol' the desl"red of flux cl@istrib,,,,tion ,It these c@@ poin@Ls. 5. The combipation W-itla the ,trjii,,itLire o'@ ,@ dynai,no electric I niachiiie, o'L a. fle'Ld iiil"ynet clist-ri-bi-.tted windii3g co prisin.o- a '-Q pItiTalitiT o'L colls for each p6le. on@, poles, e@ch p6le conil)risin(_y t pILir,,tlity'of ii'len-ibers @nelliding o Liter I)ole men-ibers, tl-ie, aa D at the inner tii) of each o.- Liter 1)ole Diember b@ing less th,,in the gi-D at the center p-,trt of tl-i@ centr,,ti pole m@n-iber. aiid the o-Liter pole tip of ch o Lit t T-0 ea ermos ,, le meiiiber -pproachiiig t.he netitr,,tl axis at a distance not ureater than its distance from,the eqliivalent armattire surface, 6. The combinatio@.@i -with the arrfiattire of a @,.5,clynamo electric rnachine, of E--@ field n-iagnet h,,ivino,T a clistriblited - ",incling @omi,)rising, t i)ltir-,Iitv of c6ils for etch pole, at-id 1,-ol6s, each i)ole@ coinprising a, pILir-.ility of'n-ic-iilbers i'LielLiOring o-Liter pole, inelubers, 'LI,.e inner tips o of said outer pole me-mbers bei-Lig formed -witl-i a relativel-.v sharp @,el-ite anol@ (i-iot n-iateri,,illy greater th,,tn 45") ancl the clistance of @e,,tcl-i @Llip 'Lroin the eqtiivalent armature surf,,ice beir le@s than the dist,,tnce froll'i tb-e ceht al 35 part of the, central pole ineiilber, and the o.Liter pole tip of each olitermost pole memb@r -ol)roaching tli.e netitral axis at a distince, 1 ot al inbre th,,i-n its dist-aiiee h-om the equivallen't, ,tr a'u re siirface. @ m u 40 7. The con-ibi-,l,,Ltion with the armat-Lire of a ciyp.aiiio electric inachip-e,, of a, field m et . @gn li.aviiig ,t, distribtitecl winding comdrisinu a pliiralitv of coils 'Lor e,,tch pole, a@cl po'l'es, eael-i i-)ole comprisiiig a plutality of so@ce@cl 45 pole niembers, sgici pole ifl(@inbe@s a@r@nged to i)roi ect over the c6ils. so thlt the iDIer tip O-P eich of the oliter pole nien-ibe s i slibst,,tn r s ti",Illy as close to tb-e ceii@uer of the pole as ti-ie oliter Dole tii) of 'che acl-',,,,cent inner i)ole iiielil50 ber. S. The combination witl-i the armature of a. dyn,,im,o elec'uric in,,tchine, of @a field niagnet 1-ta,ving ,t O@istribtitecl -",iiidi-ng cornprisin a 9 PILir'll;,Lv of coils for ea-.h pole, aiicl poles 55 con-ildrising a 1:)Itirality of :)ole inembers inelliding outer pole ineiaibers, the eLlrv,- Ltllres 04L the T-,,tc-_s o-f the pole meinbers di:fferii-ig so that 'u -1 c-Lir,@Tpture of the face of an o-Liter pole iiiember is g@-el-iter -, in that of an -Ldjacent ini'ler pole nlember. 9. The I n VT, ith tlie , ire O.-' a c6@r-lb'natio L dvp.,tiilo electric idacliine, of a field nia net 9 li,%viii (_-T ,t dis'riblited -winding com-Drising a 1?!Li.-ality of coils for each pole ,t'-,id poles 65 comprisiii a pl-Liraliti, of bole meiiibe-rs in9 eluding outer pole members, the etirvatures of the faces of the ole men-ibers cliffering so p 'u-hat the c-tirvati-ire of the face of an ol,,ter pole i:iiember is (yreater than that of a-n adja,cent ole member, and theetirv,,itures beiri- o p slich.that the air gap between s,,tid f a-,es and the eqtiivalent armatlire slirface varies subst,,tntially inversely as the clesired wave of flux distriblition. In testiii -ionv where6f, 'we affix o-Lir siana- .5 tLLres. JOHIN F. R DOUGLAS. EDWARD. W. KANE. so li 0 IOU io5 110 115 120 125 130

Patentecl Nov. 18, 1930 l@7829200 UNITED STATES PATENIT OFFICE JOHN F. H. DOUGLAS AHTD EDWAFD W. OF It'-T -T@-@, A-UXE, W7SCONSIN SYNCHRONOUS D7,'I%T--'@-.-@t!O-ET-ECTRIC :PYIACHIFB Otir inven,-ion relates to dyn,,tmo electr;lc machines of the synchronotis type, an(I more particularly to field inag-ilet s'Lriiet,-Lires iii wilich the winding is distributed. lp- iiiachines of th;.s type previously macle, t'he pol.e face has either been made concentrig -wi'ih the, armature stirftee or -",ith the severil n-ieii-ibers clivergiiag froin the ari-iiitlire stirftee tow,ird the outer 1),4rt of cael-i I)ortioii of the 10 poles. The latter of these two forins is much superior to the first in its wave forn-i o' '-,idticed electroinotive force, in that sudden ,tnd rapid changes in the magnetic fILix density opposite the o enino-s over the exciting p coils is largely avoicled. Howlever, the wave of incluced voltage of the latter form is by ,lo means a sine w,,ive and shows rn-,Lrked defects Tvhich eatise Linclesir,,tble iio-ise in 'telephon(3 ei-rcui4LS adjacent to lines to -which 20 such machiiies are connected. The deviation of the voltage from a sine @vave -Ulay be traced to ,t cieviation of ti-ie flux deiisi.ty oii the armature surface from a siiiusoidal distribution in stich a i-iian-,ier that coiisicler,,tble 25 con-ipoli--nts or harinonies of noise-produeing qualities, or high frequency as coniparecl to the usef,,il current, are present. In order to,improve the magiiet-ic flux distribution, we slitpe the pole faces as follows: 30 The coli'L<)ur of the pole f,,tee is shapecl so that uricler elcli member of the pole the gap is Y.%ried approxin-i-,itely inversely as the sine -@,e o flti li tri ,ive or o-@'her desir,,ible Ay, a r x s Th-Lis the gap -Linder e@Leh mem@t)er 35 farthest from the pole center is to the gap n arest the pole center inversely as toe Lltix e densities clesired opposil-e these oints, arici p iiot as the mauneto-motiie forces ol' the coils. 40 The result is that the iiieli-ilation. of tlae central iuember is soinewhat less tha--i IK-liowii forms and the clivergence of the o-Literi@,iost ii-ieiiabers somewhat rtiore. IkloreoA,er, -we sh,,tpe the oii'Ler iiiembers with a -reater etirvature tli,,iT-i the center members so that a'u -,I-it-.i-riied,late poiftts Viie clesired tqtix clistributioi,, bp, h,,icl. N@TB fincl th,,tt these depart-tires from ustial practice decidecllv improve- the fiilix distriblition aiid the iva-ite of ducecl electronlotive 'Lorce, aDd I-,,nee t"iie in efficiency of machines of this type. Application filed Ap@,il 27, 19P5. Serial No. 26,113. I Ve malie ih- 01,11)s bT-l e4 t@her side o' i - -L he coil ope niijo@s uiiequal, but ii-i the ratio of the av ,,tilable magneto-iiaotive forces on the two fa ces. However, iiisteacl of iiialcii-ig the (y@)p at the iniier coriier oii qn ouler pole iiieiiiler 5s eqt i,,tl to the, gap -t the ceiiter of tl-ie pole, ,ie ma ke theii-i in clirect r@itio as the -n-iag--Lietomo -,,ive forces ,Lt these two places, and in inAe rse rill-io as the sine Wave or o'ther desirqbl e W-,ve of fltlx clis@Llribution. The coil s,,)aeers or re'L-,ainers oii tli-e iietitril axis are j--o,,,de of no-Ti-@-na,-netic iiiaterial 'Ot th ir ef-fect of divertilig mlo'netic e to avoi li,- ies fi,om the triiiature. The pole tips of op posite polqrity iuost nearly approacliiilo- .65 ea cli other ,t,-e e@,@uendecl Lin'L-1.1 they (tlie pole @ UIPS a,@:e tpproxim,,-@-elv as close to the iieutral ,ixis -.s thev (the pole 'Lips) are to the eo, -Liivtle,.it arm@@ture surface. The pole face o.@ the oliter iiiember,adilicen'u 'to the, pole tips '70 -is correcte,,l ilso for the ctirvl)ture of the lin es of iiaiaiaetic force iii 'U-his region. F or best r-.stilts the corners or tips of egcli ofthe outer pole members iiearest the ceii'Le@. oL the poles qre inacle as sh,,lrl) -,Ls possible 75 ai-icl v@,,;th ,tii aiigle so that their sides acljaced-t to tl-ie slot openiiig are inel-'- Iiecl awgy from tlae armafure ancl tway from the center of the pole. Haviiag clescribed otir i--tiventio--Li in gen- .80 ei-al term, s we give ior the L'tiller uiide,,,- sl-aiiclipg Of our iiivention @uhe following descr-ptioii in connectioii -with 'Uhe drainiiigs, iii which Fic, I is a det,,t@l cleiation of a mao c@l chiiie eml @ino- oiir in'veiit;@or., parts beiii 85 Qhown in see@lion; and Fi(,. 2 is a section upon the line A--,\- of Fig. 1. The proper selection of the of ii-- m.-,'Utire slots a-id coi'- pitch i-, i,,7,ilportai-it in the desigii o' Liiv alteriiatiii curreiit iiiaI 9 chii-ie. Bytheproperchoice@--T'L'Alesef,,i(-toi@s of design any one or lu-@N o resiOLual- litriilonies be g@,-@eatl3, reci@iced, the ratio o'@ the hf,@ri-,--lo@ics I.e:f@lu in ti-ie volt,,,,ge t,) tl-.a@L i-ii "iie -qiix -er -ile(I elt a id piteli (liffei@e,-iLial 'Lacbe. iiio., It, I i @ @-ors, respecti-vely. Oi-ir iny--i-itioii is diree'Lecl -,,)artictil,-irly to -,@ecluce tbe li@irl--Yloiai-cs ]]I tile f-i-Lix iv,-,ve a3icl he-l-ce i-Li, tl-.e voltage V,,,ave. The ,,r-Tp.,iture Vl"i,,-iclin(-- joes Pot i, trocitic@2 no load and the sariie oii,, nei-, harinonies at

20 nl,@iiiiier. TI-ie centrftl 'mellltleil ;S,-- 2 1,7821200 -r Cent recluctioii given by the bel" t-, -@ i cl actual air-g,,tp and the air-o-ai) coefficieiit. P, ZD , piteii factors of @iiiy give,.i cles."Lgn ob- TI-ii@ teriii "air-gap coefficient" is 9-Iso knoivn taiiied with olir inveiition. as @ge.-iten ion coefficieiit for effective air-o,,ti) At Lull load the reactioii iiitroin toothed arii'lattires", tlid -Linder th@e@e dtices harmo,-i-cs iii tre, v@olt,@o-e iiot names is refeired to by C. C. I-T-a-wiKiiis i,,-i present 6rigii-ia'Lly. These ar@a @o-, trol-ed 'ii his book "The Dynaiiio", Pittinann's 1922, TO -id Lh XI syna,tiiy c,,,.se by proper eiioice of ,rriiature wii pa,(;e 492, and ,tlso in e inde list o' ing aiid by the r,-tio of -Lqe'@,l bol8i page XVIII. pere turiis, b- I )7 metliocls -v;ell kiiow,-o @-o t,-'iis While this extension co-efficient or airlo ar'u. Otir disc'_oses no lmic,3-,Ove- O"lp coeffic@.eiit as compi-itecl by the cliiarts ill 7a @zn -b utl-iorit-137 @itecl v,,tri-s to @ soina exteli 4. meiit@in this etT-ec'L-, bLiL ,ye i,e'iy oi tlie 4u e a elin-iii-iation oi hvrmon-cs b37 @llo, i@lie t,]-, -V - Ln - _le di-s'uance from the -Iqtiii,alent ariiiac,-Lire irorl-, @7hieii iii i'use'.,f 1-ias ai-i -.qvol e'l- sLirface -L4-14 to the tips of tae teet'ia 11 -is C - i e r x l c e 1 9 - feet ,it no loi-,l a-.-id ftill load. slibstantially onsL,,in'u. TI st,. 1, 19 15 The spide-,- is I and is mo rteci o ,L sliaft may e L re, 1-1 11 . , th re'o , bo assliiiieci as a eirc(Ilar 80 SI--iolv-ll)) 'i@n Iily -,vell-kT-Io@,- n @<lviii(y as its a@,is the o-I @'h e ('lot SL,i@ports ti-,e,poie - ,)TOL-e or core 2. 141,,tch sh,@it. It is froin- th-.@s equilviT-,-ii" is divide,,l iii@o p6i@ riemb-Irs 3, 4 ",IIcl 01 gaps is sectired t-o the po'.@e vol@e -'@n In-N7 sliotild b,- reelzoned. Tl-.e fn--es o--@;@'Ll iiienibers 3, 4 5@ ,ilr@, 15, 16 I'l- ; Vile ne'ui ctlly a - LI ni @Ll ',I n O' IDIcLv b-, Ct;@ i-il el (lo, - co,-ners OrL 'uil,)s of 'h,,6se -,'aces -@,he poe sired, 'or the pui@pos3 of b.,,@'L-;ter ceiiter IS a,7-, 19 aud 20; -,iid the coiners or The oliter iiiei-iibers 4 -o occlo@", I ent i - r.-, 'ii3s f,,irthest froii.i the 1)ole, c er 21, ancl@rnav' be te,.-i-Ded "si,-Ie -Y-Qei-rbers". The 22 ancl 23, -esl,)e-tively. By the gai)- or 25 exciti-@n wi--Ilclill,- is clividec@, coils C), T is Tr@et-tnt the Cl@'@sta@-L Pe f o-@ql ,-Lnd I 1, show--,-i iii @Qectioi-i qiiJ i-n an-y poii--,t 0-n 'Ll,-e I)OIE -Tice m ill T'iie i-i-iiier coil 8 si-irro-Lin(Is f-lie ce-i'Ucr r:@cliel clirectioii to the eqtl4l,[, r II-, iire ber > 'IIIAT, tl-ie coil 7 siir'ctincl,-, botl-i surfic--. Tl--@i:is, ti-ie gap ,,t 18 is cl;.--taiickl bers il 4; ,hile the oLiterm6s@ coil I,) from f,-ce 154 to 30 siirroutn.ds the entire pole. The co-,itrlil_ 14, it the -@)oint IS. 0,5 of the pole 3 i-S thlis slirroiird-,cl ly"-@ ti-ie The a-D e,, 9-2 i-, in,@l de ',he l@, t'L 20 9 coi'is; the s-,cle members@ 4 -,re su,, rouncl,,-cj b-,/ z-nci the -it 21 is inide 3/2 of ti-ipmost t,ie g,,ips @-i+ 18, Lqn,-! 20 ill the co@-'-@s o---,cepf@ 8 ; ,ind tiie i-nembe-@--s -,@f 41-te core 5 .,-ire s,,i@2roiipclecL L- -, are iiot iiecessarily e Ila!. On tlie 35 ciily one coil 6. Th-Lis, if the @-oils with-@,ihe-besL, co@-1-- 1,3@ i"(- eq-Lial m,,ig-net,ic st,ren(rth. the ;,-,7e these ga@,s -",ill be -uiileq-Ll"tl. 7,@Te m (, +I-i,,@ force op. the fac-, o-f ii-,@erqbe-- 4 is ',)-,ice, gap @l't 19@ atid 18 in cl;--fc-et -r.-,ti.@6 @'is I e r-,, on meniber 5, .incl the mag--ii@cto-mctive fdree neto-mat@ive force-, on f,,tces 16 v-clcl a-ocl -t7,erse rat t - L on memb@er 3 is tliree tl-i-@,,t or, tl)c :'Li io@ gs the 46 Of meniber 5. clistril-@-Lition clesirecl it 't-h--Se poiz)+Q. The arin.)ttire siirf,,tee 9 -is @t-lo-wn @Li-vi@lecl 1,,irly, the at 9@G i-s to tl,)-e(-@--p !S cli-cectz@@ - - iiito ---lot-, lo: teelli- 11 'he t,-eth being 1- S LI' , va the mao-lietc,-i--ioti-ve forco -)-I 1-7 is tci P,irt of tl-i mc-@.t-tre core@.@ @.ich P, - 'hat f,@ n cl i p e ar LI oi, 15, -@itersely ,is '.lie de@7@reci -,l -ieti6 cielasit.NT @ Jce-,ired a@u 20 is@ t6 it c.,@- of 1,-iminatecl,iron or steel. T"Li@e s' b-- 45 tvt-leei teet@, s--rlte 1:01@ r-, --ired at 18. lAa@L,Lirf@, coi-Is 13, NN-hich r"eisl,)o tiaii o-f rfa-ce l@ seci in!I The ine.lina is ma0@ @ clisto-.qari, o-@ s@,istrble Tlie ih,-!@ii tbtt c@--F 1, G -s i k;,,i r -, i tuire core is bi7 a @-rlime- or vol@(-, r tl:iin t I-)- f, t of 15 biit -@v--tli tiie bies'. @,l vrmp. of coi.Is 6, 7 tnd 8, the in -,.ny siiit,,ibl@,- , Tlie 9 Cf 5o ttire @ s-Lirface i-s brolcen i-.qto: th@(, te-el-,h a-- d 15@ -s le-,s th ]@i-iown forr,@qs, @i n -,I tl-,,-t Slc,f,'g hilt fo,- th@e P-Li-ri-,Ose 0--c' ee-2siTn, i4, i-- fa6e 17 i$ grentel@ tr, 7- f II Ive iLom,,trl7 to m,,ili:e colnp-,I,ual-ions froiii ,t siir- sh,,il)e til-e tli@tt the Ea.) t the to e gf,,p ,,,t 18 ill-ifice wIli(,Il is Isstimecl to ti-t-- str@,- te co, iier 21 O-L';,-rerqber 3 i-@ tii 4f netic char,@teteristies tb-e to,-'thecl versel-,it @-'s flic fl,@it de,-Is, Cl esirecl f,,t 21- i--, to b-Lit -wl-iiel-i is 5 11 SM004-h core thfti' lesi--:eci ,iL 18. th@@ ,i@t@ 22 -14. is 'Uo t.@-e P-'L 19 is ',-ho ',Di7e @7,e 1,@, @,L i a stirface i-,,@ lie,,7e iiiclic-,lted,, bv ti-ie 1,J-- r r@9@f,@ ,-, "h. The eq-Liiv,,,Ient smooth a@ ,ti@illre 14 Cer@sities 'it tile t-@l-o el --n a. siriiilar m is 16c,,tted,b,,i,el@ o'l. ',he .-jps c,,f t-he t i @ e ( r i ' s 2 . @ f l i i d 2 0 p r o p c - ; r L - - , o n e c l . i q @ . 1 1 @ co face to the (listelnee of the ti-,,)s of tl,-, t?,ine,-!, b-,,,t -@,l@so one i@,).t viiies ,,S tl-ie tiire teetl-i to tl-ie pole fp-ce b-'ilnc-r or oth-il oTfl-c,.--- @-.;str;bii.. 0-TI.- coefficie-nt, -t telrn-i -w, el! ki-io-w-n tf, CT.2si@rpel.,-@ nf t-'@ rn tl, electric,@il machii-i(-S. Tb-e distqlice o@ ti-@is - t@he -ILice tlae meiii!3ers@ o@4: lie ri'l core s -oiii ti-le, -,ict S 6otli livi'ace fi- llql tids o-@-, -5 vli,e @@iven (j.3 tic., to-,-fh is foLi-,n(I by tli-e i:@-rod'Llet of the J',ice 16 0.7p m-eiiber 4, L@@ld tiaot ilL tlirn +eetl-i. the r,-L'uio of its clist@qne(@, -4rcr.-l le P-,v tl-i,-s - J I T ' - S I - i ' l O C j t h