| 摘要 |
390,235. Field control of D.C. motors. FORGES ET ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE JEUMONT, 75, Boulevard Haussmann, Paris. Oct. 27, 1931, No. 29747. Convention date, Dec. 6, 1930. Addition to 386,009. Drawings to Specification. [Class 38 (iii).] In a system described in the parent-Specification, commutation of a current equal to twice normal current at half magnetic flux, is avoided by automatically limiting the armature current. This is effected in one arrangement by energizing the independent field winding of the exciter from the supply or other source, such as an auxiliary generator or a battery, in series with the exciter armature. In the case of two or more traction motors, the exciters are connected in series, or are connected to tappings on a potentiometer. The independent 'field may also be in series with a pilot exciter driven at a speed proportional to that of the vehicle, and having a shunt field and a field supplied from the line. For preventing shocks when changing over from coasting to driving or regenerative braking, the independent field of the exciter may be connected across the contacts of a main line switch through a double pole switch. Any difference between the voltages of the supply and motor is corrected by the current produced in the independent field winding of the exciter.
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