US1807854A - Transformer - Google Patents

Description

June 2 1931. A. MEYERHANS 1,807,854

TRANSFORMER Filed June 16, 1930 Wren/or flugus/ Meyer/7008 I 8y. I

Patented June 2, 1931 UNITED STATES PATENT OFFICE AUGUST MEYERHANS, OF BADEN, SWITZERLAND, ASSIG-NOR TO AKI!IENGESSELLSCI-IAFl BROWN, BOVEBI & CIE., OF BADIEN, SWITZERLAND, A JOINT-STOCK COMPANY OF SWITZERLAND TRANSFORMER Application filed June 16, 1930, Serial No. 461,664, and in Germany June 17, 1929.

This invention relates to transformer struc tures and particularly to high voltage current transformers so arranged that the voltage therein is equalized.

The lead-in insulating bushings for high voltage transformers are very expensive and require a great deal of space which is often diflicult to provide, wherefore many proposals have been made to eliminate such bushings. Among the suggestions made for eliminating such bushings is the proposal to make the entire transformer tank of insulating material. Such insulating material tanks are, however, impractical because they are more expensive to construct than the usual iron tanks with the lead-in bushings and because of the fact that such tanks are impractical in operation because of the inferior mechanical qualities of the insulating material used. The use of high voltage insulating bushings may be avoided if the tank containing the electrical portions of the transformer structure is provided with metallic top and bottom portions separated by a tank portion of insulating material extending substantially over the length, at least, of the high voltage winding. One of the greatest of the advantages to be obtained from such structures is the fact that so-called potential dividing rings may be arranged over the windings opposite the insulating material portion of the tank particularly so as to obtain the most equal potential drop in the winding. When a current transformer for high voltage is to be combined with a voltage transformer, it is, however, still necessary to provide the current transformer with lead-in bushings of large and expensive construction, and to provide an oil chamber about the current transformer which not only is expensive but requires a great deal of space which is often extremely difiicult to obtain.

It is, therefore, among the objects of the present invention to provide a transformer structure in which the transformer tank is, at least, partially constructed of insulating material in such a manner as to avoid the use of large insulating lead-in bushings.

Another object of the invention is to provide a transformer structure in which a current transformer and a voltage transformer are so combined and interconnected as to obtain a substantially equal and uniform potential drop per unit of length over insulating portion of the transformer tank for the purpose of avoiding flash-overs or creepagcs on th outer surface thereof.

Another object of the invention is to provide transformer structure in which the several portions of a current transformer are so connected with a voltage transformer in which the high voltage winding is so arranged adjacent a tank portion formed of insulating material and provided with potential dii'ding rings connected with high voltage windin s as to obtain a substantially median potential in the circuit of the current transformer.

Objects and advantages, other than those above set forth, will be apparent from the following description when read in connection with the accompanying drawing which diagrammatically illustrates one embodiment of the present invention.

Referring particularly to the drawing by characters of reference, the reference nu meral 1 designates a metallic tank of suitable form provided with rollers for transportation of the structure and an outwardly extending flange which forms a base on which a cylindrical member 2, formed of insulating material, rests. T he member 2 is formed with outwardly and downwardly extending skirts, as is usual in the construction of insulating bushings, and s pports a metallic top or cover portion 3 which is provided with an outwardly extending flange at its points of connection with the member 2. The metallic bottom and top portions are suitably connected in a fluid-tight manner with the insulating material portion to form a closed tank structure which is so constructed and shaped as to be suitable either for indooror outdoor erection. A fluid-tight container is thus provided to form a container for the cores and windings forming the electrical portion of the transformer structure to be described hereinafter.

A core at of a voltage transformer having a high voltage winding 6, a low voltage Winding 7 and an equalizing winding 8 there- 4: preferably adjacent on, is arranged and supported within the tank in a suitable manner. The high voltage winding 6 is so arranged on the core 1. as to be entirely within the insulating material portion 2 of the tank, and the low voltage winding 7 is arranged on the core wherever convenient, it being herein shown as on the sameleg as the high voltage winding 6. The equalizing winding 8, for the purpose of reducing the stray flux between windings 6 and 7, is intermingled with the windings 6 and 7. The terminals of the high voltage winding are brought out through the metallic tank portions 1 and 3 of the tank, thereby eliminating the necessity for the expensive and large high voltage. bushings heretofore considered necessary. The terminals of the low voltage inding 7 may be brought out through either one of the tank portions 1 and 3, as maybe found convenient, for the reason that the voltage differences on such tank portions are not sufficiently great to require separation of the low voltage winding terminals.

A plurality of potential dividing rings, in the form of split metallic rings9, are arranged about the winding 6 and tne core l and are connected at equi-distant points along the winding 6 to secure an equal potential drop over the entire length of such winding whereby flashovers and creepages over the surfaces of the insulating material tank por tion 2 are prevented. The potential dividing rings 9 are supported in the proper relation within the tank by insertion thereof into grooves formed in a frame 11 of a suitaple insulating material arranged adjacent the core 1. The potential dividing rings maintain a substantially uniform potential difierence over the entire length of the high voltage winding 6 and, therefore, over the entire length of the insulating material tank portion 2. V

A cascade current transformer comprising cores 12 and 13, a primary winding 14, a sec-v ondary winding. 15 and intermediate or tertiary windings 17 and 18, is so arranged within the tank that the cores 12 and 13 are supported adjacent the voltage transformer core the ends thereof, as shown.

The tertiary windings 17 and 18 are interconnected and accordingly form equalizing windings between the primary winding 1a and the secondary winding 15 of the current transformer.

The primary winding 6 of the voltage transformer is connected across a transmissionline 19, as shown, and the primary winding 14 of the current transformer is connected into the line 19, as is usual.

The present invention provides a struc- 1 ture which not only econ'omizes on the size of the bushings required, but which also avoids the use of a special container or tank for the current transformer, thereby obtain ing a material economy of space particularly in view of the fact that the tank containing both the voltage and the current transformer is smaller than the usual tank with its high voltage tank bushing for either of the transformers. The construction illustrated and described accordingly provides not only an economy in space and in cost of construction, but also provides a structure in which an equal or uniform potential division is obtained and, therefore, greater operative safety and accuracy of electrical measurements are obtainable.

Although but one embodiment of the present invention has been illustrated and de scribed, it will be apparent to those skilled in the art that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or frorn the scope of the appended claims.

The invention claimed is: 1. In a transformerstructure, a voltage transformer, rings arranged about the voltage transformer to obtain a uniform potential drop thereover, a. current transformer arranged ad acent said voltage transform-er,

and a tank partially constructed of insu-j lating material for receiving said trans; former. i

2. In a transformer construction, a tank partially formed of insulating material, aplurality of cores arranged within said tank, a high voltage windingarranged upon one of said cores, a low voltage winding arranged adjacent said high voltage winding, a plurality of rings arranged about said high voltage winding and connected therewith, a

primary winding arranged upon another of said cores, and a secondary winding arranged upon a third of said cores.

3. In a transformer construction, a tank partially formed of insulating material; a voltage transformer including a core, a high voltage and a low voltage winding arranged upon the core; potential distributing rings arranged about said voltage transformer ad'- jacent the insulating material portion of said tank; and a current transformerincluding a plurality of cores, a primary winding arranged upon one of the cores, a nd a sec ondary winding arranged upon another of the cores.

4. In a transformer construction, a tank partially formed of insulating material joining metallic portions of the same; a voltage transformer including a core, a high voltage winding, a low voltage winding, and equali zing windings intermingled with the high voltage winding and the low voltage winding, all of the windings being arranged upon said core, the terminals of the high voltage winding extending through the metallic portions of said tank; potential distributing rings arranged about said voltage transformer adjacent the insulating material portion of said tank; and a current transv former including a plurality of cores, a primary winding arranged upon one of the cores, a secondary winding arranged upon another of the cores, and connected intermediate windings intermingled with said primary and said secondary windings.

5. In a transformer arrangement, a tank partially formed of insulating material joining metallic portions of the same; a voltage transformer including a core, a high voltage winding connected across the transmission line, the terminals of the high voltage windings extending through different metallic portions of said tank, a low voltage winding, and equalizing windings intermingled with the high Voltage and the low voltage windings, all of the windings being arranged on the core; potential distributing rings arranged about said voltage transformer adjacent the insulated material portion of said tank; and a current transformer including a plurality of cores, a primary winding arranged upon one of the cores, a secondary winding arranged uponanother of the cores, and connected intermediate wind ings arranged in intermingled relation with the primary winding and the secondary winding of said current transformer.

In testimony whereof I have hereunto subscribed my name this 6th day of June, A. D.

AUGUST MEYERHANS.

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