CHAPTER VIII. 



THE SYNCHRONOUS MOTOR. THE OPERATION OF ALTER- 

 NATORS IN PARALLEL. 



68, The synchronous motor. The operation of alternators in 

 parallel Fig. 122 shows the essential connections for operating 

 two alternators in parallel so that the combined output of the two 

 alternators may be delivered to a single receiving circuit ; and 

 Fig. 123 shows the essential connections for operating one alter- 

 To receiving circuit 



To receiving circuit 



Fig. 122. Fig. 123. 



nator, say, A t as a generator and the other, B, as a synchronous 

 motor. In the operation of an alternator as a synchronous motor 

 it is usually at a distance from the alternating current generator 

 which drives it, so that the generator A and the motor B, Fig. 

 123, require separate sources of direct current for field excitation. 

 In Fig. 1 22 the two alternators A and B form a closed circuit 

 independently of the receiving circuit exactly as in Fig. 123. In 

 fact, the interaction of two alternators which are connected in 

 parallel as generators is in many respects the same as the inter- 

 action of two alternators one of which drives the other as a 

 synchronous motor. Therefore the two cases are here treated 

 under one general heading ; in fact, the parallel operation of alter- 

 nators as generators is best treated as a special case of synchro- 

 nous motor operation 



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