Electronic trip device comprising an earth protection
US5436785A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1993 |
| Grant date | Jul 25, 1995 |
| Priority date | — |
| Expiry date | Sep 24, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/0935
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic trip device comprising, for each phase or neutral line, a rectifier bridge formed by four diodes which rectify the transformer current, a resistance for measuring the rectified current, and a circuit for detecting the sign or polarity of the measured current connected to one end of the transformer. A processing circuit calculates a value representative of the earth fault current by adding all the current values whose corresponding sign is positive and subtracting all the current values whose corresponding sign is negative. This current value is processed so as to bring about tripping when a threshold is exceeded for a preset time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.