THE INDUCTION MOTOR, 



351 



sinusoidal, i.e., the curve representing its variation is a 

 sine curve. 



If, for the present, the eftect of magnetic leakage is 

 neglected, we may say that this electromotive force will 

 give rise to a current whose magnitude = 



E.M.F. 



resistance of rotor winding' 



The direction of the induced currents is indicated on 

 Fig. 174. 



These rotor currents will produce a magnetic field in 

 the rotor itself. The direction of this field is seen from 

 the figure to be perpendicular to that of the rotating field 

 produced by the stator. As in the direct-current motor, 



Degrees of angle. 

 FIG. 175. COMPONENT AND RESULTANT FLUXES IN MOTOR ARMATURE. 



the actual field in the air-gap in which the conductors 

 move is the resultant of the magnet (or stator) field, and the 

 armature (or rotor) field. In this case also for a 2-pole 

 motor the armature field will be perpendicular to the field of 

 the stator. Consequently, the direction of the resultant 

 field which acts upon the rotor conductors is intermediate 

 between the directions of the main field and cross 

 magnetising field. The resultant field will be of constant 

 magnitude when the speed and load of the motor are 

 constant, since the rotating field of the stator and the 

 currents induced by it in the rotor are both constant w r hen 

 the motor speed is constant, and since both of these 



