EXCITERS 



361 



In the other installation l mentioned the supply system for 

 the exciter sets consists of two low-voltage generators arranged 

 for combination drive, one end being connected to a water wheel 

 and the other to an induction motor which obtains its driving 

 power through step-down transformers from the main busses. 

 The water wheel is used for normal operation. In either system, 

 each auxiliary alternator is capable of carrying the entire exciter 

 load of the station. 



FIG. 216. Auxiliary Generators with Direct-connected Exciters. 

 Supply for Motor-driven Exciters shown in Fig. 215. 



Power 



It is advisable to keep a spare exciter set on hand to replace 

 any one that may break down, inasmuch as each exciter has only 

 sufficient capacity to excite one generator only. The process of 

 changing requires but a very short time. 



Exciter Batteries. The use of storage batteries as a reserve 

 source for field excitation has of late been increasing considerably. 

 The method of connecting and operating such batteries varies 

 somewhat with the arrangement adopted for furnishing the 



1 Ontario Power Company. 



