168 



SYNCHRONOUS MOTORS 



still deduced from those of the e.m.f.'s by means of the internal 

 resistance r and an inductance; but that inductance is then the total 

 transverse inductance L t = l t +s. The sides, A %A and A A i, of the 

 triangles will therefore represent ZJ, where Z t symbolizes the impe- 

 dance which corresponds to the transverse inductance, where / 



represents the current, and where tan y = 



But OA \ and 



0.42 no longer represent the internal e.m.f.'s except in regard to 

 their phases. To represent them in magnitude as well as in phase, 

 the diagrams shown in Fig. 85 must be constructed by reference to 

 the characteristic curves for these two alternators, which curves, 

 for the sake of simplicity, are here supposed to be the same for both 

 machines. 



7,1, 7A 



FIG. 85. 



Let OM\N\ be the total excitation characteristic or saturation 

 curve obtained by plotting the excitation ampere-turns as abscissas 



and the induced e.m.f.'s at no load as ordinates. Let - =the 



V2 



armature ampere-turns produced by an effective current / in the arma- 

 ture (with A 7 peripheral conductors per pair of poles; and let us select, 

 for Fig. 84, a scale such that the current- vector A I will also represent 

 these armature ampere-turns according to the scale of abscissas in 

 Fig. 85. We then draw AB\ and AB 2 , perpendicular respectively 

 to OA\ and OAz (in Fig. 84); and we point off AFi and AF 2 both 

 equal to MS!, and also draw F\Di and F^D^, perpendicular respect-: 

 ively to OA \ and OA?. The vectors OD\ and OD% represent the 



