RECTIFIERS: Til/- >T.\ dlh'ONOUS CONVERTER 343 



current brushes be open-circuited or removed, the machine be- 

 comes, under these conditions, a synchronous motor of tin- rotat- 

 bg-annature type. On the other hand, if direct current be 

 supplied to the brushes and commutator, and the slip-ring brushes 

 be disconnected, the machine becomes a shunt or compound 

 motor. 



If the machine be driven mechanically, and current be taken 

 from the slip-rings only, it becomes an alternator. On the other 

 hand, if current be taken from the commutator only, it becomes 

 a direct-current generator. Both alternating and direct current 

 may be taken from it simultaneously, and it then becomes a 

 double-current generator. 



Fio. 314. Two-pole, single-phase, synchronous converter. 



In the synchronous converter as ordinarily used, alternating 

 current i< supplied to the slip-rings so that the machine operates 

 as a synchronous motor, so far as the alternating-current side is 

 concerned. At the same time direct current is taken from the 

 commutator and brushes, and then-fore this side of the machine 

 has character! v similar to those of a shunt or compound 



itor. When -,| in this manner, the machine is said 



to be a d <'hronous eonvei 



The machine, however, may take power from the direct -current 

 supply. 0] is a direct-current motor, and delivering alter- 



nating current from the -lip-rmi:-. When i in this 



