Rotor overtemperature protection for electric motors
US4114077A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 1, 1977 |
| Grant date | Sep 12, 1978 |
| Priority date | — |
| Expiry date | Apr 1, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H11/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A system is provided for preventing overtemperature of the rotor bars of large squirrel-cage induction motors. A transmitter is mounted on the rotor and supplied with power from the rotor winding itself by a special current transformer. The transmitter is controlled by a temperature sensing element which causes it to transmit a signal in response to excessive temperature, and a slip frequency signal is also transmitted as a reliability check. A stationary receiver picks up the signal from the transmitter and includes circuitry for deenergizing the motor in response to the excessive temperature signal and for preventing energization of the motor if the slip frequency signal is not received.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.