Run-up and run-down control for async motor - uses constant voltage during run-up and run-down, with max. voltage supplied at async revs and switching in of short circuit protection

摘要

The run-up of the async electric motor is effected via a fixed constant voltage until the motor revs are nearly reached, at which the voltage is brought to the max. voltage over a short interval before switching in the short-circuit protection. The run-down of the motor is effected using a constant voltage applied for an adjustable interval, or until the standstill of the motor is indicated by a detector. Pref. the difference between the network voltage and the motor voltage is detected via the power semiconductors for one motor phase using opto-couplers. ADVANTAGE - Prevents torque jolt during run-up with max. voltage attained in short time.