Thermal protection apparatus for a synchronous machine
US5305234A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 31, 1991 |
| Grant date | Apr 19, 1994 |
| Priority date | — |
| Expiry date | Dec 31, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/934
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A synchronous machine is protected from closely spaced instances of excessive field current and an excessive volts/hertz ratio by a control system which models rotor and stator cooling to provide memory of recent periods of excessive heating. Maximum excitation limiting and volts/hertz ratio limiting modules in a microprocessor based automatic voltage regulator for the machine generate time delayed limit signals which override voltage feedback control when the respective parameters exceed threshold values. The limiters each increment a count when the associated threshold value is exceeded and generate the associated limit signal when a predetermined count is reached. The predetermined counts and the counting rates are selected such that the delay intervals are inversely proportional to the amount by which the threshold values are exceeded. The counts are decremented at a rate which models rotor and stator cooling when the respective parameters return below the threshold values. If another event occurs before the count reaches zero, the delay before limiting action is reinitiated is shortened by an amount related to the residual heating.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.