US1389148A - Transformer - Google Patents

Description

W. M. McCONAHEY.

TRANSFORMER. APPLICATION FILED JUNE 8, 1917.

Patehted Aug. 30,1921.

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'ATTORNEY UNITED STATES PATENT OFFICE.

WIELIAM M. MCCONAHEY,OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

TRANSFORMER.

Patented Aug. 30, 1921.

Application filed June 8, 1917. Serial No. 173,510.

To aZZ whom it may concern Be it known that 1, WILLIAM M. MoCoNA- HEY, a citizen of the United States, and aresident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Transformers, of which the following is a specification,

My invention relates .to electrical insulating structures and it has special relation to insulating structures that are interposed between members to be insulated from each other and that are ordinarily subjected to concentrations of electric stresses. These concentrations of electric stresses in an in sulating structure, against which I provide protection, arise when at least one of the members between which a difference of electrical potential obtains is in mechanical contact with certain portions only of the insulating structure.

More particularly, my invention relates to means whereby the insulating structure between the coils of a core-type transformer and the core member, which possesses a rectangular or polygonal cross-section, may be subjected to uniformly distributed electric stresses. 4

By means of my present invention, insulating cylinders that commonly circumscribe the rectangular or polygonal cross-sectional core legs of a transformer in order to insulate the current-carrying coils therefrom are subjected to uniformly distributed dielectric stresses, although the-insulating cylinders, as usual, are in contact with certain portions only of the core member.

For a better understanding of the nature and scope of my invention, reference may be had to the following description and the accompanying drawing in which Figure Tie a cross-sectional view of a transformer structure embodying a form of my invencause the insulation provided on the conductors from which the coils are wound, is not unduly stressed mechanically.

The insulating cylinders 6 and 7, preferably made of micarta, are likewise of cylindrical form which greatly reduces their manufacturing cost. In order not to impair the insulating properties of the cylinders 6 and 7, it is desirable that they be maintained in their initial cylindrical form. To reduce the space occupied in the transformer by insulating material, the cylinders 6 and 7- are so dimensioned that they cir cumscribe the core legs 2 and 3 in such manner that the corners or angles of the core legs come into close mechanical contact with the inner surface of the insulating cylinders. It is readily apparent that, unless means are provided for distributing the electrical stresses over the inner surfaces of the insulating cylinders, the cylinders will be subjected to concentrations of dielectric stresses at the points of contact with the core legs.

I, therefore, provide the inner surfaces of the insulating cylinders 6 and 7 with conducting linings 8 and 9, respectively, which may be made of tin foil.. The metallic linings 8 and 9, being in intimate contact with the corners of the core legs 2 and 3, respectively, serve to uniformly distribute the dielectric stress throughout the body of the insulating cylinders 6 and 7. In this manner, concentrations of electric stresses are precluded from forming at certain portions only on the inner surfaces of the insulating cylinders. As a consequence, the insulating cylinders may be utilized to their full insulating strength, all portions thereof being uniformly stressed.

It is apparent. that the conducting layers 8 and 9 should not severally form a complete convolution in which an electric circuit may be established in the nature of a short-circuited secondary winding. When the conducting layers are arranged in position, the break should not'be placed adjacent to an angle of the core member inasmuch as the trostatic stresses.

While I have shown and described one embodiment of my invention only, it will be understood that many modifications may be made therein without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. The combination with members to be electrically insulated from one another, of an insulating structure interposed therebetween that is in mechanical contact with certain edges of at least one of said members, and means for subjecting said insulating structure to uniformly distributed dielectric stresses and simultaneously avoiding a short-circuited turn.

2. An electrical apparatus comprising a .core member having a polygonal cross-section, a coil embracing said core member, an insulating tubular member interposed between said coil and said core member, said tube member being in. line contact with the corners of said core member, and a conducting lining for that surface of said insulating member that is in line contact with said core member in order to uniformly distribute the dielectric -stresses in said insulating member said lining being discontinuous to preclude the formation of a short-circuited turn.

i 3. A transformer comprising a core member, a coil embracing said core member, an

insulating cylinder interposed between the coil and the core member and in line contact with said core member, and a conducting lining for the interior surface of said insulating cylinder, said lining being discontinuous whereby it does not form a sl1ort-circuited Winding.

In testimony whereof, I have hereunto subscribedmy name this 28th day of May 1917.

wiLLiAM M. McCONAHEY.

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