Sustained Short-Circuit Phenomena and Flux Distribution of Salient-Pole Alternators

It is shown in Section IV that with the ordinary field forms met with in practise, the resultant flux wave under s. s. c. (sustained short circuits) will be extremely distorted, see Figs. 16, (4th wave) 23, 27, 27A, etc., for the simple reason that with the very low voltages obtained under such conditions, the fundamental of the B-curve of the field is reduced so much by the armature reaction that the higher harmonics assume a very predominant role and become several hundred per cent of the s.s.c. fundamental. See Fig 26 and Tables XI, XII, and XIII. As a corollary to the foregoing it is found that the B-curve under load will not differ radically from the no-load field form since the fundamental will remain large enough to hold its own. See Fig. 22 and also footnote (4). The cross magnetizing effect of the armature reaction is, of course, to make the B-curve unsymmetrical with respect to the mid-pole axis. Compare Figs. 7 and 22. The magnetic oscillations are studied not only by means of full-pitch stator coils but also by means of rotor coils No. 7 and 8, Fig. 3, and stator coils No. 9, 10, 11, 12, 15, and 16, Figs. 3 and 3A. Attention is called to the following facts for which explanations and theoretical proofs are offered. (1) The ripples at the crest of the e. m. f.