November 19, 1891] 



AM TURt 



59 



or, &c. And the various arrows attached to the various 

 parts of Fig. 27 are all drawn so as to represent, in 

 direction and by their proportional lengths, the currents 

 as determined from Fig. 25. 



If, instead of starting with the closed circuit three- 

 phase motor (Fig. 24), we deal in the same sort of way 



winding, and consider each coil as consisting of two in 

 series but wound in opposite diiections, we arrive at the 

 symbolical Fig. 30 ; then, by interchanging the positions 

 of the coils without separating any of the connections, 

 the twelve- phase motor shown in Fig. 31 is produced, 



Fig. 28. — Transformation of a three-phase_ alternate current motor (open 

 winding), with currents differing by 120° in phase, into a six-phase moto-, 

 with currents differing by 60° in phase. 



with the open circuit three-phase motor (Fig. 20), we 

 obtain Fig. 28, by supposing each coil to consist of two 

 coils in series oppositely wound ; and then, by inter- 

 changing the positions of the coils without breaking any 

 of the connections, we arrive at the six-phase motor seen 



Fig. 30. —Transformation of an open wound combined with a closed wound 

 six-phase alternate current motor into a twelve-phase motor with current 

 differing by 30° in phase. 



where the current in each coil differs from that in the 

 preceding by 30' in phase. 



In the twelve-phase motor (Fig. 31) the current in coil 

 I is completely represented by the projection of Oa (Fig. 



29. — Six-phase alternate current motor (open winding); currents differ- 

 ing by £0° in phase, and represented in direction and magnitude by the 

 direction and length of the arrows. 



in Fig. 29, where the current in coil I is completely re- 

 presented by Oa (Fig. 25), that in coil II by the projec- 

 tion of Oy produced backwards, \}^2X in coil III by the 

 projection of OiS, &c. 



Lastly, if we combine the closed and open methods of 



NO. I 151, VOL. 45] 



Fig. XI. — Twelve-phase alternate current motor ; currents differing by 30° in 

 phase and represented in direction and magnitude by the direction and 

 length of the arrowc 



25), that in coil II by the projection of O3', that in coil 

 III by the projection of Oy produced backxvards, that in 

 coil IV by the projection of O2, &c. The maximum 

 currents then in the coils 11, II2. IV, IV-., VI, VL, will 



