| 摘要 |
PURPOSE:To obtain a failure diagnostic device which can diagnose whether at least either one of a stitching element or a diode for regeneration is in failure before starting a DC motor with a simple configuration. CONSTITUTION:While a contactor 22 for regeneration is opened before starting a drive motor 21, a control circuit 40 switches a wring of a field coil 21a to a conduction state in either one excitation direction from a non-conducting state by means of contactors 25f and 25r for advancing forward and backward. Then, while wiring of the field coil 21a is switched, the control circuit 40 detects a voltage which is applied by the voltage-application means 40 with the voltage- application means which applies a detection voltage between a main transistor 26 and a diode 31 for regeneration. When the detection voltage is lower than a predetermined specified value, the control circuit 40 determines that at least either one of the main transistor 26 or the diode 31 for regeneration is in failure and prohibits starting. |
