CHAPTER. VII 

 INDUCTION MOTOR 



200. Induction Motor. Fig. 307 shows an induction motor 

 of the squirrel-cage type. It consists of two main parts, the 

 primary or stator and the secondary or rotor and is a combina- 

 tion of a synchronous motor and a transformer. The stator is 

 exactly similar to the armature of a synchronous motor. The 



FIG. 307. Induction motor. 



rotor which takes the place of the rotating field member of the 

 synchronous motor is not excited by direct current but has cur- 

 rents induced in it by transformer action from the stator; thus 

 the transfer of power from the stator to the rotor is similar to 

 the transfer of power from the primary to the secondary in a 

 transformer. The rotor is however free to move and there is an 

 air gap in the magnetic circuit and therefore the magnetizing 

 current is large, the leakage reactances are large and the power 

 factor is low. 



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