Method of and device for protecting electrical power system
US5305174A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Sep 3, 1991 |
| Grant date | Apr 19, 1994 |
| Priority date | — |
| Expiry date | Sep 3, 2011 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02B2075/027
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electrical power system protection device includes a circuit breaker and a switch connected in series to a power line. The protection device also has a current limiting element connected in parallel to the circuit breaker. When the level of electrical current flowing in the power line, detected by a current detector, has exceeded a predetermined first set level, a first over-current detector delivers immediately a trip command to the circuit breaker. As a consequence, fault current is commutated to the current limiting element so that any drop of voltage in the power line upstream of the circuit breaker is greatly suppressed. When a state in which a predetermined second set level is exceeded by the detected current level is continued beyond a predetermined period, a second over-current detector delivers an off command to the switch, thus protecting the upstream portion of the power line against the fault in this power line. The current level is set to fall within a range which activates a momentary element of an over-current relay of a receiving end breaker of a downstream sub-system connected to the power line. In the event of a failure in the downstream power line, the receivi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.