Method for generating circuit-breaking signals
US4780789A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1986 |
| Grant date | Oct 25, 1988 |
| Priority date | — |
| Expiry date | May 20, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/44
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for generating a circuit-breaking signal in dependence upon the magnitude and duration of an excess current, where a measured quantity, derived from the excess current, is sampled, is converted into digital values, and these values are weighted in accordance with a predetermined function and are added in order to obtain a circuit-breaking signal when the sum exceeds a predetermined comparison value. In order to improve upon a method of this kind in such a manner that, in the case of a diminishing excess current, a false interruption of the circuit is safely prevented, an auxiliary quantity (.DELTA.i) is formed which corresponds to the difference quotient or differential quotient of the measured quantity (M) and when the absolute amount of the auxiliary quantity (.DELTA.i) is already below a predetermined limit value and the sampled value of the excess current is below a predetermined threshold (S), the addition is interrupted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.