Apparatus for fault direction-comparison protection
US4317151A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1979 |
| Grant date | Feb 23, 1982 |
| Priority date | — |
| Expiry date | Dec 17, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/262
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
With heretofore known directional comparison protection systems working with fault direction detectors at both ends of a line section which is to be protected and data transmission between both end stations as well as transmitters and receivers and comparison-evaluation devices for narrowing or sectionalizing the location of the fault site with respect to the line section to be protected, the reliability of such sectionalizing procedure, especially in the case of faults near to an end station, when working with series capacitors or capacitance, is dependent upon the response of the protective gap of such capacitors. With non-response there are produced transient oscillations which can falsify the directional determination. The invention solves this problem by using distance protective relays as the fault direction detectors with line replica or image impedance, which can be switched in the sense of a zone staggering protection. The image impedance for the directional comparison protection is set greater than the impedance of the line section to be protected, preferably is approximately equal to the forward network impedance of the relevant station.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.