Abridgment of induced voltage of electrical machines

The object of this paper is to describe and discuss a general equation for the induced voltage of electrical machines having parallel coil sides, and which includes as special cases single- and polyphase-induction motors, synchronous generators, d-c. generators, synchronous converters, and static transformers. The application of the general equation to most of these cases is illustrated, and a number of interesting problems which may be solved by means of it pointed out. A characteristic of this equation is that no restrictions are placed on the velocity of the moving conductors, or on the rates of pulsation and rotation of the flux; but these may vary in any arbitrary manner which can be given a suitable analytic expression. The several methods for the reduction of harmonic voltages are classified and their limitations discussed in such a way as to leave in mind a vivid picture of the process. Tables and curves have been prepared for comparing the effects of the skew, pitch, distribution, and phase connection harmonic reduction factors. A new method for summing the finite series of the distribution summations is given in Appendix II of the complete paper.