INDUCTANCE AND CAPACITY 



431 



of the Leeds & Northrup Co., in which a small rotary converter 

 or motor-generator set is controlled by an electrically operated 

 tuning fork. 



The connections of the apparatus are shown in Fig. 253. The 

 circuits necessary for driving the fork are shown by dotted lines 

 and the synchronizing circuits by solid lines. 



D.C.Side 



Motor Generator 

 Set 



Diagram for Leeds and Northrup speed controller. 

 K z 



Electrically driven tuning fork. 

 FIG. 253. 



The speed of the direct-current motor is first regulated by a 

 rheostat in the armature circuit so that the motor tends to drive 

 the alternator at a speed about 10 per cent, above synchronism. 



If it is desired to maintain a frequency of 60 cycles, for instance, 

 the fork is regulated by means of the movable weights W and the 

 movable spring S, which gives a fine adjustment, until its rate is 



