Motor control system incorporating digital top speed limiting arrangement

摘要

An SCR motor speed control system having a capacitor for triggering the SCR into conduction is provided with circuitry for limiting the top speed of the motor by sensing the time of a predetermined proportion of a motor revolution to determine the motor speed. When the time is below a predetermined time interval, indicative of motor speed above a desired top speed limit, a path is closed to bypass the charging path of the capacitor.