possible to find the counter-magnetomo- 

 :ive force due to. the armature current at 

 :he moment when the armature-coils are 

 n mid position between two poles. The 

 naximum current is 30 ^/ 2 = 42.4 am- 

 peres, and the corresponding exciting 

 power is 3,400 ampere turns. This, 

 aowever, occurs at a time when the coils 

 ire well within the polar surfaces of the 

 ield-magnets and the poles produced in 

 Jae armature are between neighboring 

 Eield-poles. In this position the demag- 

 netizing effect must be naturally small. 

 [t will be a maximum when the armature - 

 poles are opposite the field-poles, and at 

 that moment the exciting power of the 

 armature-current is about 1,700 ampere 

 burns. This value must, therefore, be 

 deducted from the exciting power applied 

 bo the field, to obtain the true effective 

 exciting power which is causing the flow 

 of lines. Thus the value 10,300 is ob- 

 tained, to which corresponds a flow of 

 215 lines through the armature, giving 

 the induced electromotive force of 2,400 

 volts. 



