| 摘要 |
A motor control system of the present invention includes an accurate electrical insulation deterioration detecting system. A voltage divider circuit is arranged between a negative DC output portion and a ground, through a normally open switch circuit. A detecting operation control section closes the normally open switch while a circuit breaker is opened, and places at least one of transistors electrically connected to a positive DC output portion into a conductive state, from among six transistors included in three arm circuits. A voltage across the first resistor is inputted as a divided voltage into a voltage comparator of a voltage comparison section. The voltage comparison section compares a divided voltage outputted from the voltage divider circuit and a reference voltage using the voltage comparator and outputs an alarm signal if the divided voltage exceeds the reference voltage.
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