3/8 



ELEMENTS OF ELECTRICAL ENGINEERING. 



as will appear later. Let the vector a, Fig. 10, drawn from 

 any chosen point 0, represent the current in section a of the 

 upper end-ring in Fig. 9. It is evident from the choice of signs 

 in Fig. 9 that the current in section b is the vector sum of the 

 currents a and I, the current in section c is equal to the vector 

 sum of b and 2, etc. Therefore, in so far as the vector diagram 



5 . 6 ^ 



Fig. 10. 



of currents is concerned, the currents in the respective sections 

 of the end-rings may be represented by vectors drawn from any 

 point O to equidistant points on the sides of a square. A fur- 

 ther condition, however, must be satisfied by the current distribu- 

 tion in the rotor, namely, that the RI 2 loss be a minimum. 

 This condition is satisfied by choosing the point in Fig. i o at 

 the center of the square as shown in Fig. 248 of Chapter XIII. 



