Selsyn instruments for position systems

Selsyn instruments are miniature salient pole synchronous machines excited by alternating current. They are used to transmit electrically, to one or several of the instruments acting as the receivers, the rotation given to another of the instruments acting as a transmitter. This paper presents a study of the behavior and accuracy of these instruments at standstill and under synchronous rotation giving results equally applicable to large Selsyn power motors and generators. The data presented are useful in connection with the problems of remote control, synchronous coupling of power drives, the transmission of indicating signals, or remote metering.