Apparatus and method for motor overload protection using an elapsed-time signal for enabling computation of motor temperature data independently of temporary power interruption
US5644510A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 25, 1994 |
| Grant date | Jul 1, 1997 |
| Priority date | — |
| Expiry date | Nov 25, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/08
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Apparatus for electrically coupling a motor to a power source and providing overload protection to the motor includes a controller having a programmable module for periodically computing data indicative of motor temperature based upon motor current. The controller supplies an output signal based at least upon the computed motor temperature data. A contactor, responsive to the controller output signal, deenergizes the motor whenever any last-computed motor temperature data reaches or exceeds a threshold temperature. The last-computed motor temperature data is stored in a memory prior to the motor being deenergized. A signal from a timer circuit indicative of elapsed time after the motor is deenergized, together with the stored motor temperature data, enable the programmable module to compute fresh date indicative of motor temperature subsequent to the motor being deenergized. The programmable module, upon initialization with the fresh motor temperature data, can readily resume periodic computation of motor temperature data based upon current now drawn by the motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.