USRE13830E - Transformer - Google Patents

Description

n :UNITED sTATEs PATENT IoEEioE.

NEWTON A. WoLcoTT AND WILLIAM c. WOODLAND, `or WARREN, oHIo, AssIGNoRs TO THE PACKARD ELECTRIC COMPANY, `OF WARREN, OHIO, A CORPORATION OIEl g omo.l

T all whom `'it may concern:

.'Beit known that we, NEWTON A. WOL- v lco'r'r` andWViLLiAM C. WOODLAND, both of clear,

Warren, in the county of Trumbull and State of Ohio, have invented certain new and useful Improvements in Transformers; and 'we do hereby declare the following to be a full, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

It is the customary practicevin modern transformer construction `to use what is known as reduced core section, that is, the portion of the iron which is directly under the Winding is reduced in cross-section so yas to allow a shorter mean turn of copper.

In such transformers the laminations of the legs are of different widths, that is, they are composed of central sections and outer narrower sections, forming a figure substantially -{-shaped in cross-section, wherein one of the bars ofthe cross may be considered as extending all the way across the figure. These leg sections are connected ref spectively by yoke sections in which heretofore no account has been taken of the diftransformer construction is an inequality of ference in the ratio of the magnetic density between the portions of the yoke connecting the inner or more extended legsections and such leg sections, and the magnetic density in the portions of the yoke connecting the outer or narrower leg sections and sucli narrow leg sections themselves. For example, while the ratio of magnetic density between the portions of the yokes connecting the more extended or intermediate sections of the legs has been, weiwill say for example, approximately one, or unity, the ratio between the magnetic density of the portion of the yoke connecting the outer or more restricted leg sections and such leg sections has borne no such equality, the. density of the more restricted leg sections being much greater than that of the portions of the yokes connecting such parts. The result of such magnetic density in the yokes which causes the lines of force in the yoke sections of greater magnetic density, instead of passing straight on, to -nd an easier path in the portions of lesser ymagnetic density and cross over thereto, thereby producing waste4 TRANSFORMEE.

Specification of Reissued Letters Patent. Reissued NOV. 17, 1914 1914, Serial No. 561,010. Application for reissue led May 13, 1914. Serial No.838,397. l

ful eddy currents which show up as increased core loss'.

i It is theprimary object of this invention to prevent such increase in core loss by more nearly equalizing the magnetic density 1n the various parts of the yokes. i

It is also the object of this invention to'4 cordance with our invention. Fig. 2, a top plan view thereof. Fig. 3, an edge view in elevation of said transformer core.

In the accompanying drawings, 1 'designates the central or wide leg sections connected by yoke sections 3; 2 the narrower leg sections, and 4, yoke sections connecting the said narrower leg sections 2. These sections are as usual made up of interleaved` laminations of suitable magnetic zinetal, and' the number of laminations composing the yoke sections 3, correspond, or nearly so, with the number of laminations of 'leg sections l. If, however, theflaminations of yoke sections 4 equaled in number those of the leg sections 2, as has been the custom, without making provision for equalizing the magnetic density of the parts of the yokes connecting with the different leg sections, it

will be seen that the yoke sections 3xwould carry a greatei' magnetic density than yoke sections 4. In other words, the ratio of the magnetic density of sections 1 to sections 3 wouldnot be at all the same as the density ratio of sections 2 to sections 4, assuming the sections 4 to contain the same number of laminations as sections 2. For example, while the magnetic density in sections 1 and 3 may be approximately the same, the magnetic density in sections 2 would be much ioo i greater than. sections 4. The result would be that the magnetic'lines in the yoke, inl order to ind an easier path, wouldI cross from the sections 3 into sections 4 of the i yoke, and thereby .set .up eddy vcurrents as described.

enough Lof -,the plates in ly'o'jkesections 4 to make the net .area thereof bear approximately the same ratio to that of leg sections 2 as the yoke sections 3 bear to leg sections l. The superficial area .oithe-yokeSQtions may remain unchanged. As the net crosssectional area of `the 'yoke-sections '4 yujsu ally over twice that of leg sections 2, the'desired end may be attained by omitting eabout one-half :the plates, -that is to Jsay, veye'ry i other plate .ordinarily required v`inmfa'kir1g; up the :yokesections connecting the narrow l'egsections i, y @ur aim VAis AStoequalize A'the magnetic densities in all 'partsfof "the yokes 'considered separately and'to equalize thev magnetic densities "in all `parts of theflegs considered separately so 'as to prevent 'the magnetic lines of vforce `:from straying out of rtheir proper "By means of lour invention, not'only do We minimize the eddy-currents, resulting in .According to our inventiom We Omit lower v.effect items made.

tions ffrom thefle connected;

"In Ltestimony whereof, We have signed' this specification 'in 'the presence of `two subscribing Witnesses. n

WVQLGOTT. WILLIAM iC. `WVOODLAND.

Core losses, ,hut We, at vthe same time, aosaving in the material, and these are ,of considerable .importance .in .View of the urgent .demandriforlowercore losses, and also the high cost of silicon-steel from which :transformer cores claim gas our invention In a transformer, a laminated closed mag- `nticacore ycomprising ipanallel legs-composed 'of vsections of different Widths and yokes connecting said legs, the yoke sections connecting the reduced Widthszof v'the legsbeing K; composed of a 'dijfferent'numberfof laminag sections to whichftheyare litnesses KI-NGSLEY, HNSNXDER.

are preferably

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