Performance of traveling waves in coils and windings

L. V. Bewley (General Electric Company, Pittsfield, Mass.): Professor Rüdenberg has presented an interesting analysis of traveling waves in windings, in which, by means of a Fourier integral, he represents the incident wave as an infinite series of sinusoidal components, and then determines from the differential equation in what fashion these sinusoidal waves can enter the winding. He finds that there is a critical (or cut-off) frequency beyond which an applied sinusoidal wave cannot penetrate the winding as a wave, but can nevertheless establish an exponential distribution which decays in place. This method of analysis, while little used by power engineers, is quite familiar to communication engineers in connection with filter theory (see, for example, chapter XI, volume II, of Guillemin´s “Communication Networks”).