DETAILED STUDY OF OPERATION WITH NORMAL LOAD 35 



(2) The component having a phase-difference of , 



The arrows indicate the direction of the vectors. Taking into 

 consideration the direction of YY' (in the case of Fig. 22), it is seen 

 that every wattless current A\D, drawn to the left of the line of ref- 

 erence A%Y, is a current which lags with respect to the E.M.F. 2 but 



FIG. 23. 



which leads with respect to the E.M.F. E\. If the point A\ should 

 come to the right of A%Y\ (Fig. 23), the wattless current would lead 

 with respect to E% but would lag with respect to E\. 



Applications of the Diagram of the First Kind. The diagram has 

 for its object to enable the different working conditions of the motor 

 to be grasped at a glance. It lends itself especially well to this 

 when the motor E.M.F. 2 is maintained constant, because only 

 the point A\ is then displaced,- as the result of a variation either of the 

 phase-angle 6, or else of the generator E.M.F. E\. In both cases 

 the outputs are denned by the curve which A\ describes and which we 

 will call the "locus" of A\. This locus is a circle when the excita- 



