Adaptive overload protection of electric motors and static switching drives
US4980624A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 22, 1989 |
| Grant date | Dec 25, 1990 |
| Priority date | — |
| Expiry date | Dec 22, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/1227
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Protection apparatus for an AC or DC motor (4) and a static drive (8), including a static inverter or a static drive (8). An I.sup.2 T signal is modified to take account of the frequency with which the switching elements of the drive (8) are switching their load current (at 42) and other factors. The modified I.sup.2 T signal is lowpass filtered in a filter whose cutoff frequency is also a function of the drive's switching frequency. The resulting drive protection signal is compared with a predetermined threshold. An I.sup.2 T signal is also modified to take account of the speed of the motor and other factors, then filtered, to provide a motor-related signal (at 90). Upon occurrence of an overload both the drive-related signal and the motor-related signal are indpendently capable of turning off the system by tripping a line contactor (6).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.