US2526706A - Electrical transformer - Google Patents

Description

Oct. 24, 1950 H, 5mm. 2,526,706

ELECTRICAL TRANSFORMER Filed Sept. 20, 194';

VEJV T formers.

Patented Oct. 24, 1950 UNITED STATES PATENT OFFICE ELECTRICAL TRANSFORMER Hurley Smith, Concord, N. H.

Application September 20, 1947, Serial No. 775,235

3 Claims.

This invention relates to electrical transformers of the liquid cooled type.

One of the objects of this invention is to provide a transformer of this type of light weight and of high efficiency and which is effectively cooled by the surrounding atmosphere. Another object of this invention is to provide a transformer of this type in which the edges of the laminations of the core are exposed directl to -Other objects and advantages of this invention will appear from the following description and claims.

In the accompanying drawings:

Fig. l is a central, sectional elevation of a transformer embodying this invention;

Fig. 2 is a sectional plan viewthereof, on line 2-2, Fig. 1; and

Fig. 3 is a perspective view of a liner or sealing member for preventing seepage of liquid between the laminations of the core.

My transformer includes a core 5 of any usual or suitable type and formed of laminations in the usual manner. The transformer is provided with m the usual coils, 6 representing the low voltage .coil, and l the high voltage coil, the two coils being separated from each other by suitable insulating material 8, such as commonly used in transby the core and also extend about the middle portion or leg 9 of the core. The core may be formed of laminations of any suitable or desired shape, those shown in Fig. 2 by wa of example including for each layer, a lamination ID of sul stantially E-shape and a straight end piece ll connecting the three legs of the E-shaped laminaery of the core is exposed to the surrounding The core has suitable openings formed therein through which the two upright portions -or legs of each coil extend, so that these upright portions of the coils are completely surrounded atmosphere so that the outer edge portions of all of the laminations will be exposed to the cooling effect of the surrounding air. I provide two relatively small tanks or housings l4 and i5 which are clamped in the core. In the particular construction illustrated, these housings are provided with outwardly extending flanges l6 and I l which are apertured to receive bolts l8 which extend through holes in the flanges and in the core, and consequently, when these bolts are tightened by means of the nuts l9, the laminations of the core will be pressed together and the edges of the housings will be pressed against the lower and upper laminations of the core. Suitable gaskets 20 are preferably provided between the flanges of the housings and the core.

Suitable means are provided for preventing seepage of oil or other cooling liquid outwardly between the laminations of the core and also for preventing moisture from the surrounding atmosphere from seeping inwardly between the laminations into the interior of the transformer. This may be accomplished in any suitable or desired manner, particularly by means of a liquidtight liner of such form as to keep the oil or other cooling and insulating liquid entirely out of contact with the core. A liner of this type is preferably made of a pliable or flexible membrane, which has good dielectric properties and is also oil proof, such for example as plastic sheets, such as are commonly used between layers of glass to form safety glass. Any suitable sheet material which is inert with reference to the cooling and insulating liquids used in transformers may be employed, such for example as a relatively rigid or stifi material, which may be formed into the desired shapes required.

A liner of this type may be made by winding sheets of this material around the upright legs of the coils before the laminations of the core are stacked through and around the coils. Such sheets 22 may have their upright edges seamed together as indicated at 24 in any suitable manner. Certain materials of this type may be cemented to form the seams 2t and other materials may be heat-sealed. After the laminations of the core have been placed in operative relation to the coils, the upper and lower ends of these sheets may be bent over to form the upper and lower flanges 25 and 25, or these flanges may be in the form of separate pieces which may be cemented or heat-seamed to the upright tubular parts 22 of the liner. (lonsequently, when the upper and lower tanks are assembled to the transformer, portions of the flanges 25 and 26 may be clamped between the edges or flanges of the tanks or housings, and the upper and lower laminations of the core. The particular liner described has the further function of forming an additional insulation between the core and the coils.

In the particular construction shown in Fig. 1, I have shown the flanges of the lining member clamped between the gaskets 2-2 and other gaskets 28. In this manner, a liquid-tight seal is formed within the core of the transformer, so that the escape of cooling liquid outwardly through the laminations is prevented, and moisture from the air is prevented from entering the transformer and mixing with the cooling liquid therein. Furthermore, when the transformer is filled with liquid, as indicated at SU in Fig. 1, the pressure of the liquid will urge the material of the liner against the laminations into a good heat exchange relation thereto, so that heat from the cooling liquid will be readily transferred through the liner to the laminations, and this heat will be readily dissipated from the outer edges of the laminations which are disposed to the surrounding atmosphere. transformer has the further advantage that heat generated in the core itself is conducted directly by the laminations to the surrounding atmosphere, while in transformers as now commonly used in which the transformer is contained in a tank, the heat generated in the core must first be transferred to the liquid, then from the liquid to the tank wall and then to the atmosphere. In my improved transformer, the direct transfer of this heat from the core to the atmosphere substantially increases the capacity of the transformer as well as materially decreasing the size and weight of the transformer.

The tanks or housings may be made of any suitable or desired material. The upper housing may, for example, be made of porcelain or other dielectric material, thus forming a good insulation for finals 3i for the high voltage coil which may be mounted directly on the upper housing. The lower housing It may be also made of porcelain or of drawn or cast metal with bushings of porcelain or other insulating material 32 extending through holes therein and through which the low voltage conductors 43 torwhich are connected with the low voltage coil 6 extend to the outside of the transformer. The lower housing member serves as a storage reservoir for the cooling liquid, and also collects any sediment which may be precipitated. The lower housing member preferably is formed with a flat base so as to form a support for the transformer during handling or shipment, or on which the transformer may rest when supported on a. platform.

These small housing members greatly reduce the size of transformers of any given kilowatt capacity, and thus facilitate the handling of the same and the mounting of the same on poles or other supports.

The liner, being located entirely within the transformer, is, consequently, protected against damage or rupture.

It will be understood that various changes in the details, materials and arrangements of parts, which have been herein described and illustrated in order to exp ain the nature of the invention may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim as my invention:

The

1. In a liquid cooled electric transformer comprising a core formed of laminations, primary and secondary coils arranged on said core and extending through openings in the same, and housing members secured to and pressed against the opposite ends of said core, that improvement in which the core forms a part of the container for a cooling liquid and in which a liquid-tight lining of electrical insulating material is arranged about all of the inner edges of said laminations and formed of a flexible material which is substantially inert with reference to the cooling liquid and which prevents escape of said cooling liquid between said laminations and the entry of moisture from the exterior of said core into the interior thereof, said flexible lining being pressed by the said cooling liquid into engagement with said core and means forming a liquid-tight connection between said lining and said housing members.

2. In a liquid cooled electric transformer comprising a core formed of laminations, primary and secondary coils arranged on said core and extending through openings in the same, and housing members secured to and pressed against the opposite ends of said core, that improvement which includes a lining member flexible sheet material inert with reference to the cooling liquid employed in said transformer and comprising a liquid-tight tubular portion arranged within each of said openings and pressed into contact with the edges of said laminations facing said openings by said cooling liquid, to keep cooling liquid from seeping between said laminations, the ends of said tubular portions being flanged over and extending parallel to and beyond the end laminations of said core, said housing members having open sides facing said core and enclosing the portions of said coils which extend beyond said core and which are arranged in abutting relation to the end laminations of said core, the turned-over ends of said tubular lining members being clamped between said housing members and the end laminations of said core, and bolts connecting said housing members and pressing the same against said core and forming the liquid-tight joint with said flanged-over parts of said lining members and said housing members.

3. In a liquid cooled electric transformer comprising a core formed of laminations and having openings therein through which portions of the high and low tension coils of the transformer extend, and dished housing members which have open sides facing the opposite ends of said core, that improvement which includes a lining member of electrical insulating material and including tubular parts forming linings for said openings in said core and extending crosswise of the laminations thereof, said lining member having flat ends extending parallel to the end laminations of said core and with which said tubular parts have liquid-tight connections, the outer portions of said flat ends of said lining member being disposed between said housing members and the end laminations of said core, and clamping means urging said housing members toward said end laminations of said core and said edge portions of said flat ends of said lining member to form a liquid-tight joint between said edge portions and said housing members and to compress said laminations, said lining member being made of a flexible sheet material which is inert with reference to said cooling liquid and which is pressed by the cooling liquid into contact with comprising UNITED STATES PATENTS Name Date 10 Frank May '7, 1907 Number Name Date Hunt July 7, 1925 Champlin Aug. 4, 1925 Hanchett Dec. 9, 1947 FOREIGN PATENTS Country Date Great Britain Nov. 22, 1935

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