Monitoring insulation and fault current in an A/C current network to provide load shutoff whenever differential current exceeds a certain response value
US6392422B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 14, 2000 |
| Grant date | May 21, 2002 |
| Priority date | — |
| Expiry date | Apr 14, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/42
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and device for monitoring insulation and fault current in an electrical alternating current network. The differential current formed by vectorial addition is detected between at least two network conductors. Load-cut occurs when the differential current exceeds a specific threshold value. In order to increase safety and to protect human beings, the amount of alternating current contained in the differential current is detected as a first network variable, and the network alternating current between at least both network conductors and between at least one network conductor and an equipotential bonding conductor or a neutral conductor is detected as a second network variable. The product between the amplitude of the amount of alternating current contained in the differential current and the cosine of the phase angle &phgr; between both detected network variables is determined as a measure for the resistive fault current of the network and load cut-out occurs when the determined product exceeds a specific threshold value. The product can be calculated directly or, even better, it can be determined indirectly without knowledge of the individual variables. One particular advan…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.