Discussion on “the effect of iron in distorting alternating-current wave-form” at New York, September 28, 1906

Charles Proteus Steinmetz: This paper deals with the wave-shape distortion produced in alternating-current circuits by the introduction of iron. It is a theoretical paper, and while of scientific interest appears at first of rather little-practical value to the electrical engineer. There is, however, to-day only a very short step between pure scientific investigation and engineering practice; and I hope to show you that the phenomena dealt with in this paper, and similar phenomena, are of very great practical importance in alternating-current distribution; that is, wave-shape distortion may lead to effects not only very marked and pronounced but occasionally disastrous. In general, in investigating the effect of iron in alternating-current circuits, the curve of exciting current is calculated from the hysteresis cycle of the iron. Dr. Bedell proceeds inversely by superposing different harmonics of current. From these complex currents he produces a hysteresis loop, noting whether this hysteresis loop is a reasonable one or not, and deriving therefrom relations regarding the relative intensity and phase of the triple harmonic in the wave of exciting current. As far as the investigation goes, it extends only to the fundamental and triple harmonics; the investigation of higher harmonics is left to a future occasion.