US1091995A - Transformer. - Google Patents

Description

N. A. WOLCOTT & W. C. WOODLAND.

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' I i i NH I I w m4 Wadpqii W Waddle/ind llu UNITED STATES PATENT OFFICE.

NEWTON A. WOLCOTT AND WILLIAM G- WOODLAND, 0F WARREN, OHIO, ASSIGNOBS TO THE PACKARD ELECTRIC COMPANY, OF WABBEN, OHIO,

A CORPORATION OF OHIO.

runsronuaa Specification of Letters Patent.

Patented Mar. 31, 1914..

A. Wontransformer construction to use what is that is, the.

known as reduced core section, portion of the iron which is directly under the winding is reduced in cross-section so as 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 figure sub-' narrower sections, forming .a stantially +-shaped in cross-section, wherein one of the bars of the cross'may be considered as extending all the way across the figure. These leg sections are connecte respectively by yoke sections in which heretofore no account has been taken of the difference in the ratio of the magnetic density between the portions of the yoke connecting the inner or more extended leg sections and such leg sections, in the portions of the yoke connecting the outer or narrower leg sections and such 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 have been, we will 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 he more restricted leg sections both of V d nected by yoke sections and the magnetic density y show up as increased core loss.

It is the primary'object of this invention to prevent such increase in core loss by more nearly equaliz ng themagnetic density in the various parts of the yokes.

It 1s also the object of this invention to I provide a transformer having yokes in'evel'v part of the section of which yokes indivldually considered the magnetic densities are approximately equal, and having legs 1n every part 0 which legs individually considered the magnetic density is approximately equal. In order to more fully describe our invenpanying drawings wherein,

Figure one form of transformer constructed in accordance 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, I'designates the central or-wide leg sections con- 3; 2 the narrower leg sectlons, and 4, yoke. sections connecting the said narrower leg sections 2. These sections are as usual made up of interleaved laminations of suitable magnetic metal, and the. number of laminations composing the the number of laminations of leg sections 1. If, however, the laminations of yoke sections 4 equaled in number those of the leg sections 2, as has been the custom, without makin provision for equalizing the magnetic ensity of the parts of the yokes connecting with the different leg sections, it will be seen that the yoke sections 3 would carry a greater magnetic density than yoke "sections 4. In other words, the ratio of the magnetic density of sections 1 to sections 3 would not 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 secwould be that the magnetic lines would cross in order to fi'nd an easier path,

from the sections 3 into sections 4: of the yoke,

tion, reference will 'be had to the accom-- oke sect-ions 3, correspond, or nearly so,with

I by producing wasteful eddy currents which 1 1s a new in side elevation of" I tions 1 and 3 maybe approximately the same, the magnetic density in sections 2 would -much greater than sections 4. The result? in the yoke,-

' one-half the plates,

and thereby set up eddy currents as ole scribed.

According to our invention, we omit enough of the plates in yoke sections/l 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 1. The superficial area of the yoke sections may remain unchanged. As the net cross-sectional area of the yoke .sections 4 is usually over twice that of leg sections 2, the desired end may be attained by omitting about that is to say, every other plate ordinarily required in making up the yoke sections 4 connecting the narrow leg sections.

Our aim is to equalize the magnetic densi ties in all parts of the yokes considered separately and to equalize'the magnetic densities in all parts of the legs considered separ'ately so as to prevent the magnetic lines of force from straying out of their proper paths.

By means of our invention, not only do We minimize the eddy-currents, resulting in specification in the presence of two lower core losses, but we, at the same time, effect a saving in the material,- and these are items of considerable importance in view of the urgent demand for lowercore losses,

netic core comprising parallel legs composed of sections of difi'erent widths and yokes connecting said legs, the. yoke sections con necting the reduced widths of the legs being composed of a different number of laminations from the yoke sections connecting the Widest portions of the legs. I 1

In testimony whereof, we have signed this subscribing witnesses.

NEWTON A. WOLCOTT. WILLIAM C, WOODLAND.

Witnesses:

RQH. SNYDER, L. A. MARTIN.

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