Westinghouse Electric & Mfg. Co. v. Pittsburgh Transformer Co.

10 F.2d 593, 1926 U.S. Dist. LEXIS 947
CourtDistrict Court, W.D. Pennsylvania
DecidedJanuary 19, 1926
DocketNo. 1006
StatusPublished
Cited by8 cases

This text of 10 F.2d 593 (Westinghouse Electric & Mfg. Co. v. Pittsburgh Transformer Co.) is published on Counsel Stack Legal Research, covering District Court, W.D. Pennsylvania primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Westinghouse Electric & Mfg. Co. v. Pittsburgh Transformer Co., 10 F.2d 593, 1926 U.S. Dist. LEXIS 947 (W.D. Pa. 1926).

Opinion

GIBSON, District Judge.

The plaintiff, assignee of Dann patent, No. 1,374,553, applied for February 18, 1915, and granted April 12, 1921, has brought this action against the defendant for an injunction and accounting based upon alleged infringement of said patent. The defendant has alleged the invalidity of the patent, in that previous patents cover the invention claimed, and also because the features of the patent were described in printed publications in the United States and foreign countries more than two years before the application therefor was filed. It also denies that its construction infringes plaintiff’s patent.-

The patent in suit is for an improvement in electrical transformer tanks. A transformer is a device used to transform electric energy from one voltage to another. Its form or method of operation is not involved in this action. In the performance of its functions, heat is created in its core and windings, which must be dissipated if the transformer is not to be impaired or destroyed. For ,the purpose of radiating the heat incident to its operation, it has been the practice to immerse the transformer in a tank filled with a light oil. In the operation of a very small transformer, the oil and a tank of an ordinary type were sufficient to dissipate the heat created; but, as the device increased in size and power, it became necessary to increase the cooling power by some means other than the mere increase of the size of the tank. [594]*594This was rendered necessary, in part, by the fact that the volume of any body increases with the cube of one dimension, while the surface increases with the square of the same dimension, or, in other words, because the surface of any body increases more slowly than does its volume. This necessity was met by two methods. By the first, the oil in the tank, in which the transformer was immersed, was artificially cooled by means of a stream of water passed through coils surrounding it. By the second method, the tank was constructed in such a manner as to offer a large amount of surface to the air. Transformers cooled by the first method are known as artificially cooled transformers, while those using the second are called self-cooled transformers. It is with the second class, self-cooled transformers, that our present inquiry is concerned.

By the history of self-cooling transformers prior to plaintiff’s patent it-appears that the first step in advance was taken when the transformer was placed in a smooth iron tank filled with oil. The possibilities of this type of tank having been exhausted, the transformer was increased in size and consequent power, by being placed in a corrugated iron tank. The indentations in this type increased the cooling surface presented by the plain iron tank. The improvement so created was increased by deepening the corrugations until some tanks were indented 15 inches or more. This type having reached its limit, the next step forward consisted in adding wings' or boxes to the main-body of the transformer. These parts, as the corrugations in its predecessor, were added for the sole purpose of increasing the cooling surface. They were- integral parts of the main'tank body. - An illustration of the type is found in figure 13, on page 452, of a publication of the Pittsfield-Sehenectady Midyear Convention of the American Institute of Electrical ■ Engineers. See Defendant’s Exhibit No. A — 1. -

- The next step in advance, in point. of ultimate merit, although perhaps preceding the last-mentioned construction in point of ■time, is found in a construction of the Stanley Electric Company, which, in 1898, made a tank that had external radiating tubes. See Defendant’s Exhibit No. A-12.. These tubes were detachably connected by screw joints with the top and bottom of the maip ■part of the ■ transformer tank,' and extend radially with, respect to the tank. This type has'been greatly advaneed-sinee its first use by increase in the number, and improvement in the shape of the radiator pipes. An example, although not the latest form, of this transformer is found in Harter patent, No. 1,155,656. In the Harter construction the flattened external tubes- are welded to the top and bottom of the main tank body.' In operation the Stanley device is the same as that of plaintiff. The oil in the main tank, heated by the transformer, rose to the top of the tank, and entered the radiator tubes. Becoming cool, it re-entered the main tank at its bottom to take the place of the oil heated by the transformer.

The next step in transformer tank construction was the addition, first, of a single row, and later of a double row, of rectangular radiators, with their greater lengths laid- tangentially to the tank. The operating principle of these tanks was the same as that of the Stanley construction, supra. The oil entered the radiators by means of conduits riveted to the wall of the tank. These conduits, with the pipes entering at the bottom of the tank, supported the radiators. An example of this transformer tank is found in Defendant’s Exhibit No. A-13. This transformer had a capacity of 3,000 k. v. a. It was in operation for several years when the plaintiff’s form of cooling tank was introduced.

In the latter part of the year 1914 the plaintiff company built and installed the transformer tank which is the subject-matter of the Dann patent.

Plaintiff has relied upon claims 7, 10, 11, 12,14, and 15 of the Dann patent. Of these claims we quote claims 10 and 15, as together they comprehend all the material features of Dann’s alleged invention: .

“10. The combination with a device to be cooled, a fluid in which the device is immersed, and a tank containing the device and the fluid, of a plurality of separately detachable flat and elongated radiators secured to the exterior of the tank and having their longer axes respectively extending longitudinally and radially with respect to the tank. * * *
“15. The combination with a device to be cooled, a fluid in which said device is immersed, and a tank containing said device and said fluid-‘and having flanged openings near the top and bottom, of a'plurality.of radiator units' detachably .secured"to said tank and having flanged members at the top and bottom which are adapted to register with, and be secured to, the flanges surrounding said tank openings, whereby the entire weight of each ra,diator..unit:is supported by .-the means which admit of fluid communication between [595]*595said unit and said tank, the vertical dimension of the radiating surface of each of said units being substantially .the same as the distance between the upper and lower openings in said tank.”

The patentee’s problem, which he claims to have solved by the exercise of invention, was to evolve a self-cooling transformer of considerably greater capacity than any of its predecessors in the art that could be conveniently shipped and easily installed. As the main tank inelosing the transformer had about reached its maximum for convenient shipping, the one way open to him was to obtain a greater radiating space in connection with the transformer tank; any increase in the power of the transformer itself being merely a matter of construction. The method adopted by the patentee, at least as viewed after accomplishment, seems exceedingly simple.

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Bluebook (online)
10 F.2d 593, 1926 U.S. Dist. LEXIS 947, Counsel Stack Legal Research, https://law.counselstack.com/opinion/westinghouse-electric-mfg-co-v-pittsburgh-transformer-co-pawd-1926.