US1831142A

US1831142A - Electric transformer

Info

Publication number: US1831142A
Application number: US435383A
Authority: US
Inventors: Scharli Rudolf
Original assignee: Brown Boveri & Compangie AG
Current assignee: AG Brown Boveri & Compangie; Brown Boveri & Compangie AG
Priority date: 1929-03-28
Filing date: 1930-03-13
Publication date: 1931-11-10
Anticipated expiration: 1948-11-10

Description

Nov. 10, 1931. RSCHARH 1,831,142

ELECTRIC TRANSFORMER Filed March 13, 1930 Inventor B Rudolf Scharli n I I y 5 Attorney Patented Nov. 10, 1931 UNITED STATES PATENT OFFICE RUDOLF SCH ARLI, OF BADEN, SWITZERLAND, ASSIGNOR TO AKTIENGESELLSCHAFT BROWN ROVER-I & CIR, OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY OF SWITZERLAND ELECTRIC TRANSFORMER Application filed March 13, 1930, Serial No. 435,383, and in Switzerland March 28, 1929.

This invention relates to electric current transforming apparatus and, particularly, to single phase or polyphase step-up transformers with concentric coils.

\Vhen a polyphase transformer with three or more concentric coils on each core leg is used for the transformation of voltages from a current source to two or more supply networks, the concentric coils usually have the disadvantages that at least two of the wind ings have a very small reactance which greatly endangers the safety of the transformer against short circuit, or they have a very large reactance, which causes a high voltage drop in the transformer. One method by which the above disadvantages may be avoided is by dividing one of the windings into half portions, and arranging the half portions concentrically with the other windings, thereby giving four concentric windings. Such construction, however, makes the calculation of the reactance of the several windings difiicult, and likewise makes the construction more diflicult and expensive. The use of four concentric coils naturally increases the size of the tank which can be used, and therefore requires a greater amount of space than is available under many conditions.

With the foregoing in mind, it is an object of the present invention to provide a single phase or polyphase transformer in which at least two of the coils are divided into two or more sections arranged and connected in such manner that each coil comprises coil sections of two or more different diameters.

Other objects and advantages will be apparent from the following description when read in connection with the annexed drawing, which shows one embodiment of the present invention with the coils shown in cross-section.

Referring more particularly to the drawing by characters of reference, the reference numeral 1 indicates a core member of magnetic material, as is usual, and the reference numeral 2 indicates the inner winding arranged directly about the core member.

The outer winding comprises the coils 3 and 4., each coil being divided, as shown, into alon the core le sections of difierent diameters arranged The larger section of coil 3 is disposed about and is concentric to the smaller section of coil 4, while the larger section of coil 4 is disposed about and is concentric to the smaller section of coil 3. The respective sections of the

coils

3 and 4 are connected in series, as shown. This arrangement and manner of connection provides that the reactance of coil 3 is substantially equal to that of coil 4:.

The coil 2 may, if desired, be divided and inter-connected in like manner so that the reacta ice of all of the coils may be entirely balanced. It will be apparent that

coils

3 and 4, as well as additional coils, may be divided into two or more sections of two or more diiferent diameters, and may be connected in such manner as to obtain pairs of identical coils arranged symmetrically with respect to the core member. It is immaterial whether the coils are arranged exactly concentrically with the core or eccentrically with the core, so long as the coils are divided and inter-connected to make the reactance of the several coils approximately equal.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent that various changes may be made therein without depart-ing from the spirit of the invention or from the scope of the appended claims.

The invention claimed is:

1. In a transformer, a core, and coils disposed about said core, each of said coils divided into sections of different diameters arranged along the core, a section of one coil disposed about a section of another coil.

2. In a transformer, a core, a winding dis-.

RUDOLF SCHARLI.