An analysis of commutation for the unified-machine theory

The logical treatment of the unified-machine theory is of such merit that it seems likely eventually to supersede the classical treatment entirely. The unified theory is, however, at present deficient in two respects. It requires two primitive machines, a slip-ring primitive and a commutator primitive, as the bases for analysis, and it tacitly assumes the existence of a perfect commutator. The mechanism of commutation is entirely neglected. The paper gives a new theory of commutation, which not only elucidates this mechanism but enables the performance of any machine or machine system to be developed from one basis only, namely the simplest case of two coils with relative angular movement. Each stage of the analysis is supported with a comprehensive series of experimental results. The tests involved introduce some interesting problems, and a new method for the measurement of the coefficient of self-inductance to direct currents is developed.