232 



ALTERNATING CURRENTS 



relation of magnetic flux to the current producing it, four poles 

 are formed in the stator, two N-poles in the vertical plane and 

 two S-poles in the horizontal plane. At instant (2) the current 

 I A is positive, and I B is negative and of the same polarity as in 



FK;. 224. Production of rotating field by 2-phase currents in a 4-pole winding. 



(1). The resulting N- and S-poles are again determined by the 

 corkscrew rule and it will be observed that these two poles have 

 advanced 22.5 space-degrees in a clockwise direction, whereas the 

 currents have undergone a change corresponding to 45 electrical 



