Remote protection of three phase distribution transformers
US4745512A · kind A · utility
32Cited by
7References
26Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 17, 1987 |
| Grant date | May 17, 1988 |
| Priority date | — |
| Expiry date | Sep 17, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/44
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
It is desirable to provide remote digital protection of distribution transformers. This specification discloses a protection system able to measure and compare increases in both negative and positive phase reference currents on a distribution cable feeding a transformer and to trigger a circuit breaker to isolate the cable only if the negative sequence current increase exceeds a predetermined proportion of any simultaneous positive sequence current increase. Consequently, engergizing with a 12.5% unbalance current has been found possible without false tripping.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.