4 6 



ELEMENTS OF ELECTRICAL ENGINEERING. 



Fig. 24 shows the arrangement of a shunt generator with 

 its field rheostat, A A is the armature, bbbb are the brushes, 

 and C is the commutator. The brush leads are connected to ter- 

 minal blocks to which the receiving circuit and the shunt field 



winding are also connected. Fig. 



main 



25 shows the conventional dia- 

 gram of connections of a shunt 

 generator. 



The series generator. The wind- 

 ing on the field magnet of a direct- 

 current generator may consist of 

 comparatively few turns of heavy 

 wire having a low resistance. In 

 this case the field winding is connected in series with the external 

 receiving circuit, the whole current delivered by the machine 

 flows through the field winding, and from 2 to 10 per cent, of 

 the electromotive force of the machine is used to force the current 

 through the field winding, the remainder being available for forcing 



rheostat 



Fig. 25. 



Fig. 26. 



current through the external receiving circuit. A generator with 

 its field windings arranged in this way is called a series generator. 

 In this type of generator the control of the current in the field wind- 

 ing for a given current output of the machine is accomplished by 



