Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support
Patent
1978-10-18
1980-11-25
Rubinson, Gene Z.
Elevator, industrial lift truck, or stationary lift for vehicle
Stationary lift for roadway vehicle or required component...
Having specific drive means for support
318742, B66B 130
Patent
active
042353092
ABSTRACT:
This invention concerns a control for starting an electric motor such as a three phase, a.c. drive motor in an elevator system. The motor is connected to a power source through reversible contactors and back-to-back SCRs. A speed control generates a desired speed signal to SCR trigger circuits to control the flow of current in the motor and thereby maintain the desired speed. The speed control includes means responsive to a step start signal for generating the desired speed signal with predetermined values of jerk and acceleration. If the motor overspeeds, such as in a lowering load condition, the control turns off the SCRs at a first predetermined value of overspeed and reverses the contactors and turns on the SCRs at a second predetermined value of overspeed to brake the motor. The magnitude of the desired speed signal can also be increased to a value in excess of the second predetermined value of overspeed such that the motor will not hunt between the original value of the desired speed and the second predetermined value of overspeed.
REFERENCES:
patent: 3599754 (1971-08-01), Caputo et al.
patent: 3678355 (1972-07-01), Bucek et al.
patent: 3774729 (1973-11-01), Winkler
patent: 3785463 (1974-11-01), Kuhl et al.
patent: 3973175 (1976-08-01), Anzai et al.
Duncanson Jr. W. E.
Rubinson Gene Z.
Schindler Haughton Elevator Corp.
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