268 



ALTERNATING CURRENTS 



within extremely small limits by the large self-inductance of the 

 winding, and for practical purposes the current may be regarded as 

 constant. 



In order to compound the generator for a highly inductive load, 

 an additional current must be injected into the field coils. Let us 



suppose that a second set of three brushes, spaced 120 apart, is at 

 our disposal, and that these brushes are connected to the secondary of 

 a transformer whose primary is in series with the armature winding. 

 Let the brushes be so adjusted that when a brush is receiving maxi- 

 mum wattless current, it is in the position of brush I, Fig. 161, 

 relatively to the commutator. The field excitation will clearly be 



