Differential protective relay for electrical buses with improved immunity to saturation of current transformers
US6442010B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 3, 2000 |
| Grant date | Aug 27, 2002 |
| Priority date | — |
| Expiry date | Apr 3, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/22
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A differential protective relay and method for a microprocessor-based bus differential protective relay that ensures fast and sensitive operation under internal fault conditions and offers improved stability during external fault and other non-internal fault conditions. The method uses a two-slope differential characteristic to cope with small CT transformation errors without reducing relay sensitivity. The method can also use a saturation detector to switch dynamically between the 1-out-of-2 and 2-out-of-2 operating mode depending whether or not the CTs saturate. In a 2-out-of-2 operating mode, both the differential and directional elements must confirm a fault for the relay to trip. In a 1-out-of-2 mode, if saturation is not detected, the relay can trip without checking the fault direction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.