400 THE INDUCTION MOTOR. 



direction, and these conductors may be imagined to form 

 circuits a a 1 , b b l , c c l , &c., through which the stator 

 flux is threaded, and in which it will produce currents. 

 The whole of the rotor conductors may be imagined to 

 be divided up in this way into separate circuits, the axis 



A< 



Fi. 193. PRINCIPLE OF SINGLE-PHASE MOTOR. 



of each circuit coinciding with the axis of the stator coil 

 A A 1 . These currents will continue to produce a magnetic 

 field in the rotor along the axis A A 1 . This field will be 

 an alternating field having the periodicity of the stator 

 current and being 90 out of phase with it (since the rotor 

 currents are induced by the change of stator field and 

 are greatest when the change is greatest, i.e., when the 

 actual field is zero). 



If now the rotor in Fig. 193 is moved round fairly 

 rapidly by hand, the conductors under A A 1 will move 

 across the flux at A A 1 , and will have currents induced in 

 them, the strength of which will depend upon the 

 strength of the flux and the speed of rotation. The 

 conductors in the neighbourhood of b b l will move along 

 the direction of the flux, instead of across it, and will 

 have little or no current induced in them by the rotation. 

 The rotation will consequently produce currents in the 

 rotor winding which will set up a flux itt *the direction 



