The Induction Motor

A review from Engineering News, Vol. 67: The style employed in Professor Bailey's book is that of the lecture room, where apparently the contents were first delivered. The composition is therefore informal and the reader can easily imagine that he is attending a course of fourteen one-hour lectures devoted to a corresponding number of topics. Each of these topics is the basis of a chapter in the book. The lectures take up the induction motor from the viewpoint of...
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A review from Engineering News, Vol. 67:

The style employed in Professor Bailey's book is that of the lecture room, where apparently the contents were first delivered. The composition is therefore informal and the reader can easily imagine that he is attending a course of fourteen one-hour lectures devoted to a corresponding number of topics. Each of these topics is the basis of a chapter in the book. The lectures take up the induction motor from the viewpoint of listeners who know the subject fairly well to begin with; otherwise the theory especially the deductions would make little impression.

Practical engineers undoubtedly wonder why teachers lay so much stress on the induction motor in their class work. It is, to be sure, a good motor for constant-speed work and for use in inaccessible locations, but why spend so much time in the study of it? The answer to this is that most of the fundamental principles of the electric circuit are illustrated in the induction motor. A clear understanding of its operation usually implies a fair knowledge of electrical engineering in general.

First, let us try to get the author's viewpoint in writing the book. He states in the preface that it is intended to fill a gap, which he believes to exist, between elementary books on the one hand and theoretical treatises on the other. This leads one to inquire as to the present status of reference literature on the subject so that the new book may, figuratively speaking, be rightly placed on the book shelf. The elementary text referred to by the author is apparently that found in general introductory books, in each of which are found one or more chapters on induction motors. The advanced literature is contained largely in papers presented to technical societies by writers like Prof. C. A. Adams, H. M. Hobart and Dr. Hans Behn-Eschenberg, and in a few books like those of Dr. A. S. McAllister, ("Alternating Current Motors"), B. A. Behrend ("The Induction Motor"), Boy de la Tour ("The Induction Motor"), and possibly most Important of all, of the late Dr. E. Arnold (Wechselstromtechnik). Professor Bailey's aim is to give the gist of these advanced treatises to the students who have already familiarized themselves with the fundamentals from the other source referred to, preferably supplemented with a personal knowledge of the appearance and general performance of the motor itself.

To insure a proper understanding between teacher and pupil a short review of underlying theoretical principles is first given. The similarity of the transformer and the induction motor from the electric circuit standpoint is explained and the applicability of the vector diagram is thus deduced. The correct electric circuit equivalent of the transformer and induction motor Is given and the modified form, in which the exciting admittance is assumed to be outside the motor, is adopted to simply the formulas and vector diagrams. The circle diagram is then introduced and the results of its application are interpreted. The remaining and larger portion of the book is taken up with special topics which are discussed with the aid of simple mathematics and illustrated with pictures, diagrams and numerical problems.

It is difficult, without going into great detail, to give a comprehensive summary of the contents of the book, as these are so varied in nature and as they lack somewhat in unity. The author's general point of view is that of the designer rather than that of the user of induction motors. This is the usual and natural attitude of a teacher toward a subject. He feels that, even if his pupils will never become designers (and comparatively few do), they will obtain the best working knowledge of any subject by a critical analysis of the laws underlying current practice.