Amortisseur winding protection system
US4291263A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1979 |
| Grant date | Sep 22, 1981 |
| Priority date | — |
| Expiry date | Sep 17, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/0805
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
This invention relates to a system for protecting an amortisseur winding during the starting of a synchronous motor. The system compares the actual slip frequency of the accelerating motor with predetermined slip frequencies. These predetermined slip frequencies are each associated with a timer which measures successive time segments. Each timer is stopped when the actual slip frequency, which decreases as rotor speed increases, is less than the associated predetermined slip frequency. When the timer is stopped a successive timer is started. In this manner the acceleration of the motor is broken up into time segments. The initial timer is started when the motor starts. The final timer is stopped when the rotor field current is applied to bring the motor into synchronism. Should any timer be permitted to have its timed segment expire before being stopped, the motor is shut down. There is also provided a thermal memory which receives information from the expired timer as to its associated slip frequency. This information is used to inhibit the motor from being restarted until the amortisseur winding has cooled. Previous systems were straight timing functions which crudely approximate…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.