Discussion on "wave shape of currents in an individual rotor conductor of a single-phase induction motor." Chicago, June 30, 1911. (see proceedings for June, 1911)

1911 Proceedings of the American Institute of Electrical Engineers  
Theodore Hoock: Mr. Weichsel's interesting, theoretical investigation of the wave shape of currents in a single-phase rotor has been made under ideal conditions, i.e., it has been assumed a machine without leakage and rotor resistance so that the rotor exciting current is equal to the stator exciting current, or in other words that the no load current with short circuited rotor is twice the no-load current with rotor winding open. The actual measured values, however, are smaller than those in
more » ... ler than those in the ideal motor, vary ing between 1.60 to 1.95. The reactance, and especially the rotor resistance has a vital influence upon the secondary exciting current, reducing it as low as 60 per cent of its theoretical value. The derived equations in Mr. Weichsel's paper should, therefore, be corrected in figuring the actual amplitude of the current. Bearing this in mind it may be found valuable to apply the equations in investigating local fields, which are set by the rotor currents under certain conditions, and which cause sometimes very inconvenient phenomena in the machine. A. S. McAllister: The author makes mention of what he calls the " Fynn method " of treating alternating-current prob lems on a basis similar to those of the direct-current motor. Just what he intends to cover by the expression " Fynn method " is not clear, but since he contrasts it with the Ferraris method of resolving the single-phase field into two fields rotating in op posite directions, it is probable that he means the resolution of the field in the single-phase induction motor into two components in space and in (approximate) time quadrature. Although this method has been employed in the recent publications of Mr. Fynn, it seems improper to attribute to him credit for originating this method which has long been in use, and was employed by others in publications antedating the descriptions by Mr. Fynn. An early treatment relating to this method, and possibly the first to be published in this country, appeared in the American Electrician, in June, 1902, where the qualitative relations were accurately presented. If by the " Fynn method " the author means the (imaginary) separation of the secondary rotor winding into two stationary circuits in electrical line with, and in electrical space-quadrature
doi:10.1109/paiee.1911.6660023 fatcat:a43ng5d2bbcfxigtbx5ijodpv4