| 摘要 |
PURPOSE:To allow quick restart of a drive motor stopped through function of a contactor. CONSTITUTION:A temperature sensor 40 detects the temperature of a motor 34 for driving a digger and when the detected temperature exceeds a maximum allowable level, the contacts 52, 54 of a contactor are opened to protect the drive motor 34. When the load increases and the temperature of the drive motor 34 falls down to a stop level lower by a predetermined level than the maximum allowable temperature, the contacts 52, 54 of the contactor are opened. After the drive motor 34 is stopped, the contacts 52, 54 of the contactor are opened regardless of interruption thereof to rotate the drive motor 34 and the digger is drawn out of the earth before the temperature of the dive motor rises to the maximum allowable level. |
