Protective circuit for an electric motor
US4504881A · kind A · utility
18Cited by
4References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1982 |
| Grant date | Mar 12, 1985 |
| Priority date | — |
| Expiry date | Dec 10, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/093
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A protective circuit for an electric motor comprises a frequency signal generating circuit for generating a frequency signal in accordance with the rotational speed of the motor, a switching circuit switched over to either permit or cut off supply of current to the motor, and a detecting circuit for detecting that the period of the generated frequency signal has become larger than a predetermined period due to a decrease in the rotational speed of the motor, and cutting off the supply of current to the motor by the switching circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.