Inductance measurement to detect fused relay contacts
US11817281B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 2022 |
| Grant date | Nov 14, 2023 |
| Priority date | — |
| Expiry date | Feb 24, 2042 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2047/009
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.