General Electric Co. v. Allis-Chalmers Co.

199 F. 169, 1912 U.S. Dist. LEXIS 1155
District Court, D. New Jersey·Decided July 30, 1912·Published

Opinion

REEESTAB, District Judge.

The bill is in the usual form for injunction and accounting. It charges the defendant with contributory infringement of the patent in suit by reason of its manufacture and sale to the United States government of apparatus embodying the improvement of said patent, which were installed at Minodoka, Idaho, in what is known as the “Minodoka Project of the United States Reclamation Service.”

The defenses are, first, invalidity by reason of lack of novelty; second, nouinfringemeut.

In the specifications Steinmetz describes the object of his inven- . tion as follows:

“My invention relates to the distribution of alternating currents, particularly to polyphase distributions. It has its most important application to three-phase systems, but others are not excluded. It lias for its object to provide a means of equalizing the voltages upon the several sides ,of the system, or of ‘balancing the lines,’ as it is often called.
“It has been" proposed to connect transformers wound for three-phase work with the Y system of connection, and to run a neutral wire from the common junction of the coils back to the generator. Where the secondaries are also connected with the Y system, this neutral wire on the primary side is a necessity, because, although a neutral may also be run from the secondary side, this will not equalize the load, hut with an unequal distribution of load the three secondary voltages will become unbalanced and greatly unequal. Nothing holds them at an equality, but, on the contrary, they change and adjust themselves so as to be proport ioned i.o the three secondary [170]*170currents. The neutralizing wire on the primary side running from the generator to the transformer must necessarily be of sufficient cross-section, to equalize "the load, and still it is normally an idle wire. This is, of course, objectionable, and deprives ' the three-phase system, when so installed, of one of its characteristic advantages, to wit, economy in copper cost. The generator also must be specially constructed where this is done, inasmuch as an additional sliding contact must be provided for the neutral wire.
“To obviate the difficulties thus pointed out, X have devised my invention, which consists in winding the primaries of the transformers with delta connection and the secondaries'with Y connection and using a neutral or equalizing wire on the secondary side of the system only, and I have found that by this arrangement so long as the primary voltages are constant the secondary potentials also are constant, irrespective of the balance of load upon the secondaries. * * *
“I thus not only obtain the advantage in transmission of current at long distance of confining the equalizing wire to the- secondary distribution only, but, inasmuch as this may be connected to fixed terminals upon the motors, I avoid the additional sliding contacts already referred to.”

It will be observed that, while the patent deals with systems wherein alternating currents of electricity are generated, transmitted, and distributed for use, it involves the distribution of such currents only in what is called the three-phase system. It deals specifically with transformer connections between the generator and the distribution circuit, in combination with the use of a fourth wire in such distribution circuit, in three-phase systems wherein the problem is how the transformer shall be connected in system so as to obtain the best results in the distribution of energy and avoid the troubles due to overloading one or more of the three-phases.

The improvement is purposed to produce a three-phase system which shall permit unequal loads in the distribution circuit having four wires, without the attendant unbalancing of voltages in the system.

Only a brief description of such system and the devices used therein is necessary for present purposes, which is as follows: The transformer consists of an iron core, a coil of wire wound around the core, called the “primary,” which receives the electrical energy to be transformed, and a second coil of wire also’ wound around such core, called the “secondary,” which delivers the transformed energy. This transformed energy may be delivered in any desired voltage; the difference in voltage depending upon the relative convolutions of the primary and secondary coils. In the’ earlier days the generator delivered current directly to the transformer in the immediate neighborhood of the consumption or translating devices, but in case of long distance transmission, as greater economy resulted by transmitting a higher voltage than it is practical to produce by a mechanical generator, transformers called “step up transformers” are introduced near the generator whereby the low voltage currents developed by such generator are converted into currents of high voltage for transmission, which are reconverted into low voltage suitable for the operation of such consumption or translating devices, by other transformers called “step down transformers” located in the vicinity of such devices.

[171]*171Many alternating current systems involve only a single pair of supply wires, and are known as single-phase systems. Others utilize more than one current, and are known as polyphase systems. The three-phase system uses three transmission wires in which exist three phases of currents. These currents, however, do not attain their maximum value synchronously, but are displaced, or out of phase, so that their maximum values are successively attained. In the three-phase system, the combining of the three wires avoids the necessity of having two separate wires for each circuit, any one being capable of serving as a conductor for the return current in the other two as long as the load carried — current strength — in each circuit is substantially equal.

In combining these wires, two methods of connection are ordinarily used, known as the “delta” and “star” or “Y” windings. In the delta, the coils are connected end to end, forming a closed circuit, a line conductor leading off from the junctions between each two adjacent coils; while in the star, or Y, three ends of the coils are connected to a common point, the opposite or outer ends being connected respectively to the line conductors. The form of the Y connections permitted the irse of an additional wire running from the common point referred to. The equalizing of the loads, however, is not always commercially feasible or desirable, and when the demand upon one circuit is greater than upon the others, and an inequality in current strength ensues, the whole system is likely to be upset, unless some special means are used to correct it. This upset is due to the going down of the voltage in the circuit carrying the greater load with a corresponding increase in the voltage in the other circuits, causing a choke effect in that primary or those primaries of the transformer which have the lesser demand for current made upon them, due to the law governing the action of the transformer; for, adopting the summary of Expert Thomas’ testimony set forth in complainant’s brief—

“tlie most salient characteristic of the transformer is that current cannot flow in one of its windings unless there is also a flow of current in corresponding quantity in its other winding.

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General Electric Co. v. Allis-Chalmers Co., 199 F. 169, 1912 U.S. Dist. LEXIS 1155 (D.N.J. 1912).

199 F. 169 (General Electric Co. v. Allis-Chalmers Co.) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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