SAETT OCH ANORDNING FOER DETEKTERING AV EN ASYNKRONMOTORS VARVTAL

摘要

For determining the speed of an asynchronous motor use is made of the most manifest tone in the frequency spectrum beneath an overtone to the basic tone of the motor current. The frequency difference between the overtone and the tone in the subjacent frequency spectrum is determined, and thereby the slip and speed of the motor can also be established.