A.C. multimotor drive maintaining selected speed ratios at all speeds within well defined limits

It is usual for manufacturers of drives for processing machines to supply individual regulatable drive motors equipped with electronic speed-control systems. These control systems are unable to control the motors within closely defined speed limits, especially during erratic load conditions. The paper, however, describes a system of drive motors in the well known synchronous-tie connection which therefore have a well defined speed relation between the motors. To enable speed adjustments for each motor, electrical differentials combined with standard mechanical variator gear are inserted. This concept greatly reduces the usual inaccuracies in the mechanical gear. To avoid speed oscillation in the synchronous tie, the main drive motor is powered by the slip-frequency network of the system and is mechanically coupled to the transmitter. Basic calculations for designing the system and a description of a processing machine equipped with this drive are also included.