Low current ground fault relay
US6327124A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 4, 2000 |
| Grant date | Dec 4, 2001 |
| Priority date | — |
| Expiry date | Feb 4, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/33
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A ground fault relay, especially useful to detect motor leakage currents due to insulation failure. The invention operates in two (2) modes. The first mode is a "look-ahead" mode where possible motor circuit insulation failure is detected prior to the electrical motor being turned on, and the second mode is "real time" mode which detects leakage currents after the motor is turned on and during running of the motor. Processing circuitry is disclosed which enables a user to set predetermined values of leakage current to be detected and to trip the relay after comparison of the leakage current and the predetermined value, if the former is larger than the latter. This invention is able to accurately detect extremely small values of ground leakage current without experiencing nuisance tripping due to extraneous noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.