Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support
Patent
1990-10-31
1993-07-20
Gaffin, Jeffrey A.
Elevator, industrial lift truck, or stationary lift for vehicle
Stationary lift for roadway vehicle or required component...
Having specific drive means for support
187119, 187120, B66B 502
Patent
active
052295583
ABSTRACT:
A method and an apparatus for the control of an elevator a.c. or d.c. hoisting motor driven by a frequency converter unit, or by a rectifier unit, supplied by a three phase power source is disclosed. The voltage of the mains power source is monitored using a voltage measuring unit. The frequency converter or rectifier is supervised by a control unit which selects a speed reference curve, best suited for a run. The controller unit allows the elevator speed to be varied continuously with the mains voltage so that the elevator always travels at the highest possible speed. When an undervoltage condition is detected in the mains power source, the rotational speed of the hoisting motor is reduced without modifying the acceleration so as to avoid an overcurrent if the rectifier or inverter switches. If, in addition, the acceleration is decreased before the maximum speed is obtained, a higher maximum speed may be obtained for a given low level of supply voltage. The solution offered by this invention enables the elevator system to work at undervoltages as low as 60%.
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Gaffin Jeffrey A.
Kone Elevator GmbH
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