Digital calculation type differential relay
US4825326A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1987 |
| Grant date | Apr 25, 1989 |
| Priority date | — |
| Expiry date | Jun 10, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/44
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In differential function calculation processing, a value of differential function f(d) is calculated using differences between a plurality of predetermined number p of differential current data Dd sampled at different sampling times. The differential current data is data obtained from differential current Id or a sum of data Dj (j=1 to n where n is the number of the respective terminal currents) obtained from respective terminal currents Ipj. In restraint data calculation processing, restraint data Dr is calculated using respective terminal current data Dj sampled at the same sampling time. In restraint function calculation processing, a value of restraint function f(r) is calculated using differences between a plurality of predetermined number p of restraint data Dr sampled at different sampling times. Then, in comparison processing, the value of differential function f(d) is compared with the value of restraint function f(r). If the value of differential function f(d) is smaller than a value, modified by a predetermined relationship, of restraint function f(r), an inhibit output is generated in the comparison processing. Differential relay processing inhibits a trip operation of …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.