Method and device for finding faults on electric lines by the principle of low impedance
US4458285A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 20, 1982 |
| Grant date | Jul 3, 1984 |
| Priority date | — |
| Expiry date | Sep 20, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/382
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The invention relates to a low impedance excitation system for use in distance relays. In such a system the low impedance check is carried out by comparing the phases of signals (U.sub.D,U.sub.S) which are obtained by forming the sum and the difference from an image voltage signal (U.sub.A) and a line voltage signal (U.sub.K). The triggering characteristic is formed in the complex impedance plane by means of the combination of at least two different triggering characteristics, mainly a circular (K) and a lenticular (L) characteristic, in order to avoid overlapping between the triggering area and the active load area (W) and in order to achieve an adequate arc reserve on the whole length of line to be monitored. The switching over between the different triggering characteristics (K,L) takes place as an operational function of the phase difference (.beta.) between the image voltage signal (U.sub.A) and the line voltage signal (U.sub.K).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.