CHAPTER XIV. 

 THE SINGLE-PHASE SERIES MOTOR.* 



140. Behavior of a direct-current motor when the supply voltage 

 is suddenly reversed. Any direct-current motor will continue 

 to run in an unchanged direction when the supply voltage is 

 reversed, because the reversal of the supply voltage reverses both 

 the armature current and the field current. Therefore any direct- 

 current motor might be operated by a repeatedly reversed supply 

 voltage, that is by an alternating supply voltage, if it were not for 

 certain effects which are produced at the moment of voltage 

 reversal. 



In the case of a shunt motor a reversal of the supply voltage 

 would be followed by a slow dying away of the previously exist- 

 ing field current and a slow growth of a reversed field current, 

 because of the very large inductance of the field winding ; whereas 

 the current in the armature would quickly drop to zero and an 



* The following papers give a very complete discussion of the theoretical and 

 practical aspects of the single-phase commutator motor. 



Single-phase Motors, by Max Deri, Transactions of the International Electrical 

 Congress, St. Louis, 1904, Vol. Ill, pages 129-148. 



Alternating-current machines with commutators, by Marius Latour, Jbid. t pages 

 149-154. 



Transmission and distribution problems peculiar to the single-phase railway, by 

 P. M. Lincoln, ibid., pages 186-193. 



Alternating versus Direct-current traction, by F. Niethammer, ibid., pages 194-271. 



The Westinghouse single-phase railway system, by Clarence Renshaw, Electric 

 Journal, Vol. I, pages 134-149. 



The alternating-current series motor, by F. D. Newburg, Electric Journal, Vol. 

 II, pages 135-140. 



Single-phase railway motor control, by R. P. Jackson, Electric Journal, Vol. II, 

 pages 525-532, and 762-763. 



Alternating current for Railway service, by B. G. Lamme, Street Railway Journal, 

 January 6, 1906. 



Alternating Current Motors, by A. S. McAllister, published in 1906 by The 

 McGraw Publishing Company, Chapters XIII to XVI on the repulsion motor and 

 on the series motor. 



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