US1430862A - Dynamo-electric machine - Google Patents

Description

Patented Oct. 3, 1922.

UNITED STATES PATENT OFFICE.

HENRY WILLIAM TAYLOR, OF'BILTON, FREDERFIG'HORTON CLOUGH, OF. HILLMORTON, AND FRANK PERCY WHITAKER, OF RUGBY, ENGLAND, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A C0RTEOIEtA'I'IOIN' OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Application filed June 10, 1919. Serial No. 303,101.

T 0 all whom it may concern Be it known that we, HENRY WILLIAM TAYLOR, a subject of the King of Great Brits ain, residing at Bilton, England. Faun. ERIC HORTON CLoUGH, residing at Hillmorton, England, and FRANK PERCY WHITAKER, residing at Rugby, England, subjects of the Kingof Great Britain, have invented certain'newand useful Improvements inDyna- Inc-Electric Machines, of which the following is a specification.

Our invention relates to dynamo-electric machines and more particularly: to the Wind-,

in s-of alternatingwurrent machines.

n large alternating-current generators in which the windings disposed in the armature slots, consist of conductors of consider abledepth, the magnetic flux across the slot arising from the current in the conductors gives rise to a parasitic voltage within the conductors which isliable to cause local or unbalanced currents, thereby producing undue heating of the conductors and causing the copper in the armature to be inefficiently utilized.

It has hitherto been proposed to limit the current which will flow as a result of these parasitic voltages, first of all by dividing the conductors into a number of separate multiple bars or laminations, and secondly by continuing this lamination of the complete conductor through the complete coil, and so connecting the ends that the order s: i of the,bars in the conductors of the upper portion of the coil is the reverse of the order of the bars in the conductors in the bottom portion of the coil. It is found, however, that on large machines with very deep conductors, the local currents which flow even when these provisions are made are still excessive and impose limitations on the design of the machines.

It has also hitherto been proposed to limit the current which will flow as a result of parasitic voltage first of all by dividing the conductor into a number of separate multiple bars or laminations, secondly by continuing this lamination of the complete conductor throughout the winding, and in addition thirdly by transferring the top lamination of the conductor to the bottom at the end of each coil, the number of laminations having been previously chosen to correspond seyto the number of coils per pole per phase or the number of coils per phase. It is found, however, that with large machines with fractional pitch or chorded windings, local currents will flow even when these provisions are made and these impose limitations on the design of the machine.

The magnetic flux which extends through the body of the bottom conductor of a slot at any instant depends only upon the current being carried in this conductor and increases gradually from zero at the bottom or the conductor. The flux extending through any other conductor nearer the mouth of the slot depends not only upon the current which that conductor is carrying, but also upon the amount of current in the conductors below the one in question. The flux passing across such conductor therefore may be considered to be partly variable depending upon the current in the conductor and partly constant dependin upon the total current in the number of conductors below the conductor in question. The flux here mentioned as extending through the body of a conductor is that which upon the rise and fall of current cuts the bottom of the conductor but not the top.

According to the present invention therefore, we arrange to continuously insulate separate bars of which the conductor consists, throughout a coil, or throughout the complete winding, as the case requires, and to connect these separate bars at the ends of the half turns or at the ends of the coils, so that the amount of constant flux linking the conductor in one or more half turns is exactly opposed by the amount of constant flux linking the conductor in another or in the rest of the half turns.

In the accompanying drawings, Figs. 1, 2 and 3 diagrammatically illustrate forms of our ,lIIVQIllIlOIl.

In carrying our invention into effect ac cording to the modification illustrated in Fig. 1 in which we have Shown two slots containing the conductors of a Z-turn coil of a Q-Iayer winding, we connect the ends of the various multiple bars so that the parasitic voltages generated between the bars of conductors 1 and 4' are cumulative and are in opposition to the cumulative parasitic voltages generated between the bars in conductors 2 and 3'. By cumulative voltages are meant those tending to produce currents in opposition when these currentstend toflow through any bar in opposite; directions.

It will he understood that the two slots illustrated are not adjacent slots but occupy positions around the armature a full pole pitch apart or nearly a pole pitch apart according to Whether the Winding has a full or afractional pitch. The lamina a of the conductor 1 is shown at the bottom of the conductor and it will be seen that a is also on tlEG lOWQZ' side of conductor 4', that is the side nearest the bottom "of the slot, \riiereas it is on the upper sides of conductors 2 and 3. It will be seen that the constant fiur z and therefore parasitic voltage arising therefrom in conductor 1? is zero otv'in to the fact that there are noconduc tors'lje'lox'v it while the constant flux in condue-tor a to which conductor 1 is cuin'u l'atively connected is 3 as there are three conductors beneath it, two of these however belonging to another coil. Onthe other hand the onstant flux in conductor 2 is 1 ahd in conductor 3 which is cumulatively connected to it; is 2 making a totalof'3 in opposition to the 3 in conductors 1' and 4' so that tl'ie'effect of these fluxes in producing eddy currents between the laminations isin this case eliminated. The inv'enti on, however, may be similarly appliedtb coils of any number of turns, so that the'parasitic currehtsivhich flow between the lamina-tions may be either completely eliminated or re} d'uced' to a negligible value. x

lVhere it is not convenient to make the connections described Within the coil itself, the separate laminations or bars of the conductors may be continued from coil to coil and the bars so connected and reversed in successive coils. 01' in successive groups of coils that the parasitic voltage generated in every conductor in every slot is always practically counterbalanced by a similarly placed conductor in another slot. p V

In the type of winding with multiple bar conductors in which the single bars of the conductor occupy successive positions in the conductor in successive turns, the parasitic voltages entirely eliminated when the coils of the Winding span a complete pole pitch. Vfhen. however. the coil spans a fractional portion of a pole pitch the parasitic voltages are not cmnpletcly eliminated in the usual manner in which this type of vinding is constructed. In applying our invention to this type of winding therefore. W0 arrange for the bars of the condtu tor to occup successive positions toward the nnuth oi the slot on one pole or group of poles of the machine, and after completely reversing the order of the bars. We arrange for the bars to occupy Sucv n etaoii le stle helmets:

F F h i gling? p012:

of'the machine. Fig. 2 illustrates this form at Que-an ti nrae as a i the ;i at e metastases a pitch of four-sixths. The Winding 0 only o'n phaseeisshown, the slots and portions of slots left empty are to be occupied by the coils of"theseeond phase constructed in a similar manner. The bars of the conduc: tor are designated by the numerals 1 to emit I aiegtirawaig-i i hasten cha n; the u er half of'sldtjl; the bars' area rangedinsequence, 1 being at the top of the slot. .:lhe bar's their 'om'plete the turn by passing along tliebotto inbtslot '5=,"when itwvill be seen that" they are re ers'dfifi order, bar; rising me t thebotton'wdt the not asfi's 'usnalf is this 5 of winenig: Passing now new son a; aria-shite observed that after being-'seeeesstvely transferred over the cOils-Oi Gfie pete the laminatiofis of the conductor are reversed-in order and are "shccssively I transferred in the pbs'ite direction we; the ee ircnlemrs ertile i second polei s 1 i 'P P 'It "will be appa ent that-the' constrhcti ofi is not ,lit'riiteqto e coil with one want oilrlfy but the same e. imin'ati'on ofi pamsiue an: rents between t e bars 'off the eendueter is effected ina mt l'tneurn cb'il whenever the other bf thebondiictdts aha" also the winter of transference *is"r'evei'sed in'" pa ssifl through the coils of theascendpore;the in dividual transference taking place a ifi filie usual eens' traaidn at meander eaeh ebiit We at netnmifieursweeyhawk/m nions choice of, the eulnbr ot sepatne; 'Hare' n which'tlie connector is difiidedtotlie'numbefi of time or'siots'pe nasean any one 5016 but we may'ar'ra-nge for the number others in the conductorto beequa l to the total number of coilsin" series on a1lthe-'poles in a y he phase, andhy dividing'thefcon the groups, We successively transfer the hairs in tne opposite direction in theother'portion of the Winding. Fig. 3"illust/ratesthis form of oiir ifirenjtion imam it as in Fig. 2 we have" shown the method of winding a Q-phase machine having two poles, the Winding having a pitch of four-sixths. "The conductor' in this casehowever" is divided into six oars corresponding to the total number of coils per phase, the individual bars of the conductor bein designated by the numerals 1 to 6. From the drawing it will be seen that in the upper half of slot 1' these bars are arranged in sequence, 1 being at the top of the slot. The conductor then other pole,

passes through the bottom slot 5 where it will be seen that it is reversed, bar 1 being now at the bottom of the slot, as is usual in this type of Winding. In subsequent coils we then arrange that the individual bars occupv successive positions in the slots, so that firstly in the 12 bottom half slots each bar occupies every position in the slot, and secondly with regard to the 12 top-half slots, the order of the bars of each group is reversed in the one pole with regard to the order of the bars in the same group of the as for instance in the top of the second coil of the first pole the order of the top group of bars is 1, 2, 6, 4, 5, While in the top of the second coil on the second pole the order of the same group of bars is reversed and is 5, 4, 6, 2, 1, 3, so that whatever the phase of the currentin the bottom of the second slots on each pole. the effects upon the Winding occupying the top portions of these slots, is eliminated and no eddy current loss results from this cause.

While We have illustrated and described above the best embodiments of our invention of which We are now aware. it Will be understood that these embodiments are illustrative merely and that our invention is not limited thereto, but that our invention is set out in the following claims.

What we claim as new and desire to secure by Letters Patent of the United States, is,-

1. A dynamo electric machine having slots and a plurality of windings located therein, said windings being formed of conductors composed of a plurality of insulated laminations, certain of said slots containing conductors of difi'erent windings adapted to carry currents which differ in phase, there being for every arrangement of the laminations of a conductor in a slot under the infiuence of flux elements due to the presence of currents in other conductors in the some slot a reversed arrangement in the second slot under the same. influence of flux elements due to the currents in other conductors in the second slot.

2. An armature provided with slots and a Winding located therein, said Winding comprising a plurality of pairs of turns, the conductors of one turn of each pair occupying slots spaced from the slots occupied by the corresponding conductors of the other turn by a full pole pitch, the said conductors being formed of a plurality of insulated laminations so connected and arranged that the effect of the constant flux elements upon one of a pair of turns is eliminated by the effect of the constant flux elements on the other of said pair.

3. An armature provided with slots and a winding located therein. said Winding comprising a plurality of pairs of turns, the conductors of one turn of each pair occupying slots spaced from a slot occupied by the conductors of the other turn by a toll pole pitch, the said conductors being formed of a plurality of insulated laminations so connected and arranged that the effect of the constant flux elements upon a half turn of one of a pair of turns is eliminated by the effect of the constant flux elements upon a half turn of the other of said pair o1 turns.

4. An armature provided with slots and a winding located therein, said winding comprising a plurality of pairs of turns, the conductors of one turn of each pair occupying slots spaced from the slots occupied by the conductors of the other turn by a full pole pitch, the said conductors being formed oi a plurality of insulated laminations, the order of the laminations in the conductors being reversed in the two turns oi each pair in slots which are spaced apart by a full pole pitch.

5. In an armature Winding formed of conductors consisting of a plurality of insulated laminations, a series of coils occupying successive slots and a second series of coils occupying successive slots spaced from said first slots by one pole pitch, the laininations being successively transferred in. adjacent slots and the order of the laminations in a coil of one series in one slot being the reverse of the order in a coil of the other series in the slot one pole pitch distant therefrom.

6. An armature winding of an alternating current machine having fractional pitch comprising conductors consisting (Ti a plurality of insulated laminations, the order of the laminations being reversed as a Whole between poles and the laminations being successively transferred in opposite directions under successive poles.

7. An armature winding of an alternating current machine having a fractional pitch. comprising conductors consisting oi a plurality of insulated laminations divided into groups, the order oi the groups being reversed between poles and the laminations being successively transferred Within its group in the opposite direction under successive poles so that each lamination occupies each and every position in the conductor throughout the Winding.

8. An armature winding comprising conductors consisting of a plurality of insulated laminations, the order of the laminations being reversed as a Whole between poles and the laminations being successively trans ferred in opposite directions under successive poles.

9. An armature winding comprising insulated conductor laminations assembled in groups. the order of the groups being reversed between poles.

10. An armature Winding comprising conductors consisting of a plurality of insulated laminations divided into groups, the order of the groups being reversed between poles and the laniinations being successively transferred each within its group under the same pole.

11. An armature winding comprising conductors consisting of a plurality of insulated laminations divided into groups, the order of the groups being reversed between poles and the laminations being successively transferred each Within its group in the opposite direction under successive poles.

12. An armature Winding comprising conductors consisting of a plurality of insulated laminations divided into groups, the order of the groups being reversed between poles and the laminations being successively trans ferred each Within its group in the opposite direction under successive poles so that each lamination occupies each and every position in the conductor throughout the winding.

13. An armature Winding of an alternating-eurrent machine having a fractional pitch, comprising conductors consisting of a plurality of insulated laminations divided into groups, the order of the groups being reversed between poles and the laminations being successively transferred each within its group under the same pole.

14L An armature having a Winding comprising coils of conductors formed of laminations which are divided into groups Within the conductor and are continued from coil to coil, the laminations being transferred within the groups and the groups transferred Within the conductors such that the effect of the constant flux linking each conductor in every slot is counterbalanced by the effect

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