Universal type motors

Heretofore the subject of universal motors has not received very much publicity but the field for these motors has been increasing so rapidly that a great deal more attention is now being given to them. The paper endeavors to bring out points of general interest rather than going into the fundamental design and other details. The term “universal” as applied to this type of motor is defined, together with a description of the operating characteristics in general. There are two types of universal motors; namely, compensated and non-compensated, both of which are described as to general design, construction and applications. The question of ratings and limitations of the universal features of both types of motors brings out some interesting points. Commutation and mechanical balance are questions demanding a great deal of attention due to the comparatively high speeds at which these motors usually operate. Some of the applications best suited to the universal motor are described, showing the possibilities of this type of motor when properly designed, manufactured and applied.