PURPOSE:To obtain a DC motor having good rectification, by providing a permanent shunt device comprising a resistor and an inductor coupled in series in parallel with a series field winding. CONSTITUTION:AC voltage is fed from a pantograph through a transformer 5 and a rectifier 6 to a DC motor 7. The DC motor 7 comprises a field winding 7f coupled in series with an armature 7a and a field weakening device 70 comprising a resistor R and an inductor L arranged in parallel with the field winding. A permanent shunt device 7b comprising a series circuit of a resistor 7r and an inductor 7l is arranged in parallel with the field winding. Consequently, combined spark voltage can be reduced even in case of such motor as being driven through a pulsating DC power source.
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