i-A] 



SERIES GENERATOR. 



-^RACTERISTIC 



tiring resistance by "fall of potential" method; see Appendix, 



17- 



Curve. By adding to the external characteristic the RI drop 

 for field and armature, we have the generated voltage or total 

 characteristic Fig. 3. 



Interpretation. The total characteristic falls below the magne- 

 tization curve on account of armature reaction, that is, the de- 

 magnetizing effect of the 

 armature current which 

 weakens the field and 

 hence reduces the gen- 

 erated voltage; for, in 

 taking the magnetization 

 curve, there was no 

 armature current and 

 hence no armature reac- 

 tion. The external char- 

 acteristic falls below the 

 total series characteris- 

 tic, on account of resist- 

 ance drop. 



The magnetization 

 curve would be higher 

 than the total character- 

 istic for all currents, if 

 in taking it the brushes 

 were given no lead, that is were in the position of maximum volt- 

 age. Giving the brushes a lead lowers the magnetization curve 

 so that for small values of the current it may fall below the 

 total characteristic. 



FIG. 3. 



AMPERES 



Characteristics of 

 generator. 



