Potential waves of alternating-current generators

The author states his purpose to be three-fold: 1. To discuss briefly certain elements in design that affect the character of the potential wave; 2. To show the effect of load and operating conditions on the no-load wave; 3. To give illustrations of the potential waves, — good, bad and indifferent, of generators, that actually supply the a-c. systems throughout the country. There are ninety illustrations in all; a study of these shows, in connection with the descriptions given, that the most perfect wave is obtained where the proper shading of the magnetic flux is obtained either by shaping the poles, in the case of definite pole machines, or the proper distribution of field winding, in the case of cylindrical rotor machines, together with an irregular, or more or less prime relation between the number of slots in the armature and number of poles.