THE CONTINUOUS CURRENT MOTOR 



155 



on one conductor and this value, multiplied by the number 

 of conductors situated in the magnetic field, gives the 

 total force acting on the periphery of the armature. 



Active and Inactive Conductors. It is to be noticed 

 that those conductors lying in the interpolar space produce 

 no turning effort; they are inactive conductors. When 

 calculating the e.m.f. of a generator it was pointed out that 



FIG. 96. All Conductors Give Torque in the Same Direction. 



these same conductors were inactive in the production 

 of an e.m.f. in the armature; in fact that portion of the arma- 

 ture winding which generates an e.m.f. when the machine is 

 operated as a generator serves to produce torque when the 

 machine is operating as a motor. In calculating the e.m.f. 

 of a generator it was found advisable to divide the active 

 conductors into two parts, those lying directly under the 

 pole face, where the field has its maximum intensity, and 



