Method and apparatus for stopping a rapidly advancing filament

摘要

A strand-advancing system, particularly for a drawing frame, has an asynchronous electric motor powered from an alternating-current source and having a plurality of separate windings forming separate poles. This motor has a rotary output speed directly related to the advance speed of the filament. During normal operation the motor is driven at a relatively high nominal speed by connecting a relatively small group of its poles to the alternating-current source. The strand advance is stopped by first simultaneously disconnecting the relatively small group of poles from the alternating-current source and connecting a relatively large group of the poles to the source to operate the motor hypersynchronously generator-fashion for a relatively short time. Then the relatively large group is disconnected from the alternating-current source and the small group is energized with direct-current voltage until the motor and strand stop.