228 



ALTERNATING CURRENTS 



The simplest type of rotating field is that produced by the 

 gramme-ring winding illustrated in Fig. 219. A gramme ring, 



(1) (2) (3) (4) (5) (6) (7) (8) (9) 



F 



(5) (6) (7) (8) 



Fia. 219. Rotating field produced by 2-phase currents in gramme-ring 



winding. 



wound for two-phase currents, has two separate windings, one 

 for each phase. Each winding consists of two sections located 



