Commutation in D. C. Machines

Abstract

In modern practice the majority of d c. machines have commutating pules by which t'e indnced e.m.f s. in armature coils undergoing commutation are compensated. Since, however, the compensating action in only done in the mean value some e m.f.s. may still remain uneompensated, the values of which being sometimes as high as nearly equal to the mean inducel e.m.f s. compensated and unsatisfaetery commutation will result.
Thus the uncompensated e.m.f.s must be paid carefull attension for rather than the mean value of the induced e.m.f. or the so-called. "reactance voltage." Since this uncompensated e.m.f. is due to the pulsation of the induced e.m.f. and the compensating e.m.f. it is an alternating e.m f. consisting of e.m.f. of tooth frequency and that corresponding nearly with period of commutation. Study of this problem needs carefull analyzation of phenomena. This has been done in this paper to a certain extent though much would yet be remaind for prae tical application.