Ground fault detection system for ungrounded power systems
US6785105B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 5, 2002 |
| Grant date | Aug 31, 2004 |
| Priority date | — |
| Expiry date | Mar 6, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/286
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The fault detection system includes at least one valid zero sequence voltage source, either from a local relay or a remote relay on a protected line. Zero sequence current is selected between total (vector sum from both ends of the protected line) measured zero sequence current or calculated zero sequence current. A zero sequence impedance-based calculation is then made and the result is compared against a threshold value to produce a trip decision. The trip decision is then applied through a normal tripping circuit or a slow tripping circuit, depending upon selected circuit conditions, involving the local and remote ends of the line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.