Differential-type protective relay
US4670811A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 19, 1984 |
| Grant date | Jun 2, 1987 |
| Priority date | — |
| Expiry date | Dec 19, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/22
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a differential-type protective relay actuated to generate a signal necessary for the protection of a bus of an electric power system when a troubled current has flown through the bus, a gapped first transformer is used to receive an output from a current transformer which is adapted to detect each current in the bus. Each output of a first detection element, which is actuated when the output of the first transformer is higher than a preset level, is fed out to the exterior only when a value obtained by subtracting the sum of the maximum of the output of the first transformer and the value of a signal obtained by shifting the phase of the output through a predetermined angle from the value of a signal obtained by subjecting the output of the first transformer to full-wave transformation is equal to or lower than a preset value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.