Procedure and apparatus for braking a squirrel-cage elevator motor fed by a frequency converter in fault situations
US5278484A · kind A · utility
Inventor
Key dates
| Filing date | Mar 7, 1991 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Mar 7, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P3/24
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A procedure and apparatus are provided for braking a squirrelcage elevator motor fed by a frequency convertor in fault situations using a direct current supplied from a d.c. voltage source. In the procedure of the invention, the current in at least one of the motor phases and the rotational speed of the motor are measured. When the elevator speed exceeds the value corresponding to the nominal slip and the motor current is less than the nominal magnetizing current, a switching device is caused to connect a direct current from a d.c. voltage source to the motor, thereby providing a magnetizing current and allowing the motor to act as an eddy current brake.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.