High resistance ground fault protection
US4878142A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 7, 1988 |
| Grant date | Oct 31, 1989 |
| Priority date | — |
| Expiry date | Sep 7, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/385
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A protection device for high resistance ground faults in a power network according to the invention has a fault detection principle which is based on an indirect study of non-harmonic frequency components of the phase currents. When such a fault has occurred, a considerable change of the energy contents of these frequencies arises. This change can be detected by a device according to the invention. If by comparison (4e) between digitized input signals (I') and a harmonic Fourier model (4d) of the same signals, i.e. generation of the residuals of the system, it is found that a difference exists, and if the corresponding loss function V.sub.N (4f) for a certain time exceeeds a lower limit value - all on condition that a zero sequence current (I.sub.O) exists - then there is a high resistance ground fault on any of the phases of the network.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.