Induction motors for synchronized drives

THERE are two types of synchronized drives of two or more mechanically independent shafts commonly known: one is the “power selsyn” or “synchro-tie;” and the other might be called the “simplified selsyn.” The first system uses, besides one or more prime movers, individual selsyn motors for synchronizing. The analysis and application of this type is very well covered in literature. With the simplified-selsyn system, each single shaft is driven by its individual motor, a wound-rotor induction motor, and these motors themselves are used for achieving a synchronized drive, without any additional selsyn motors. So far, the published analyses of this system are very poor and very little information, if any, can be obtained from the literature, which could be used as a guide for planning of such drives. Recognizing this situation, the Armour Research Foundation of the Illinois Institute of Technology made possible the performance of a series of tests which should furnish more basic information on the subject.