THE INDUCTION MOTOR. 



ably smaller for the high frequencies, as a glance at the diagram 

 shows. The following table shows the leakage factor and the power 

 factor in relation to the frequency : 



59. 1 wish to call attention to the fact that the motor for the higher 

 frequencies is here represented less unfavorably than it really is, be- 

 cause the induction in the air-gap has to be reduced if the motor is to 

 be wound for a higher frequency. The immense lagging currents in- 

 variably bound up with the higher frequency, are very clearly shown 

 in the diagram. 



60. It is to be remembered that the current in the armature is depend- 

 ent upon the leakage factor, since the transformation factor v\ forms 

 part of the leakage factor, see Fig. 6. The transformation factors 

 Vi and Vi are connected with a through equation (2), 



i 



61. Hence it follows, as t' 2 = AD . , see Fig. 6, that the cur- 



# 2 z/ t 



rent in the armature is larger for the motor running at a high frequency 

 than for that running at only 25 ~. In our case, setting v\ = Vi, we 

 get for v at 25 ~ 0.978, and at 100 ~ 0.912, therefore the current in 

 the armature of the motor for 100 ~ is, for the same AD, 1.07 times 

 larger than for 25 ~. This corresponds to an increased armature loss 

 of about 14 per cent. But as the primary current is also larger for 

 loo ~ than for 25 ~, the armature loss is still greater than here 

 calculated. Thus to the drawback of large lagging currents, it has to 

 be added the further drawback of considerably larger losses. 



62. The foregoing experiments and considerations are, within my 

 knowledge, the first attempt to deal in a rational, systematic manner 



40 



