Power interruption protection system for electric motors
US4306265A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 1980 |
| Grant date | Dec 15, 1981 |
| Priority date | — |
| Expiry date | Sep 11, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/09
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power interruption protection system for AC electric motors. An electroresponsive relay (OL) in the energizing circuit of an electroresponsive main power contactor (MC) for an AC motor is responsive to deliberately deenergize the contactor if a power supply interruption persists for more than a few cycles of the supply frequency. A motor current level detector (CLD) monitors the motor current and if it falls below a predetermined level activates a pulse counter (CTR) to register pulses from a clock pulse generator (CPG) which produces pulses each half cycle of the supply frequency. If the pulse counter registers a certain number or more of such pulses an amplifier-driver (AD) energizes the relay to effect disconnection of the motor from the AC supply. The system is disclosed both as a stand-alone system, and as combined in a system affording current overload protection modes as well for AC motors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.