Electrical switching apparatus with digital trip unit and memory reset
US5331501A · kind A · utility
9Cited by
8References
4Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 30, 1992 |
| Grant date | Jul 19, 1994 |
| Priority date | — |
| Expiry date | Sep 30, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/006
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A microprocessor based switch such as a circuit breaker has a memory capacitor charged by the microprocessor to generate an analog equivalent of a digitally modelled heat state signal. A selected resistor discharges the capacitor at a rate which models a cooling rate of a load. Alternatively, the memory capacitor may be charged to a preset value and discharged at a rate representative of the time since a trip generates digital rms representations of analog load. Terminals for rapidly resetting the analog trip memory for calibration and field testing of a long delay trip are hidden behind a removable rating plug.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.