Alternating Current Motors of Messrs. Ganz & Co., Budapest

For some time past, electricians working in the department of distribution by means of alternating currents have sought to obtain a motor which could be connected directly to the electric light circuits and which should approximate to the continuous current motor in regard to regulation and economy. The problem which presented itself involved a number of difficulties. In the first place, the efficiency of such a motor appeared to be far below that which is attained in the continuous current motor, and secondly, with certain types of alternating motors the maintenance of constant speed with varying loads is unattainable. The great drawback consisted in the fact, that if such a motor actually absorbed, say, 5,000 watts of electrical energy on, say, a 100 volt circuit, the ammeter would show, not 50 amperes passing into the motor, but probably 150; i.e., that the motor apparently consumed about three, or more, times the actual number of watts absorbed. This appeared to be a great drawback to the application of alternating current motors, as it entailed an enlargement of the conducting wires, and, indeed, an increase in the size of the transformers, dynamos, etc. This condition of affairs existed when Professor Ferraris published his ingenious experiments, which were paralleled by the motors of Mr. Tesla and others.

Recently the firm of Ganz & Co., of Budapest, have undertaken the construction of alternating current motors, and their electricians, Messrs. Zipernowski, Déri and Bláthy, after experimenting for four years on various types of machines, have succeeded in constructing a practical form. Through the courtesy of the firm we are enabled to publish the following table which gives some details of the new machine. A study of the table will show that the improved result obtained is, that the relation of the apparent energy consumed in the motor, i.e., the energy measured by means of the voltmeter and ammeter, in volt-amperes, is almost equal to the actual number of watts as measured by means of the wattmeter. This ratio of unity between these two quantities shows that the efficiency of the motor is very high. It must be noted that the apparatus upon which these experiments were made was merely an experimental one in which high efficiency was not the principal object sought for; on the contrary, the tests were made with the idea of obtaining some solution of the problem of how to obtain the greatest efficiency. Besides that, the machine was not run at its normal rate of 750 revolutions per minute, but at a lower one. These tests have led to the firm conviction that the efficiency of alternating current motors will eventually be brought up to that of the continuous current. In the new machine but two circuit wires are employed.