M/n-: It \ATOR REdri.ATION AND OPERATION 



145 



In a non-salient pole machine, tho space-direction of the resul- 

 tant flux will be the same as that of the resultant mmf . F. In a 

 salient polo machine, the space-direction of the resultant 

 flux usually is not the same as that of the resultant mmf. vector 

 F, due to the fact that the flux tends to seek the paths of mini- 

 mum reluctance. The flux therefore is distorted in the direction 

 of the pole-pieces. In salient pole machines this introduces errors 

 in the methods used for predetermining alternator regulation. 



If the armature reaction were zero, due to there being no load 

 on the machine, the resultant field would obviously be the im- 

 pressed field Fi. The no-load induced voltage must be 90 behind 

 as shown at E, Fig. 148, because the no-load induced cmf. 

 lags the no-load field by 90. 



It will be recognized, Fig. 148, that FI, F, A constitute a space 

 diagram of mmf. vectors taken from Fig. 138. E' is also a space 



tor when considered as being combined with the mmf. 

 diagram shown in Fig. 147 (c) and (d). As the linking of the 

 resultant flux F with 

 tiie armature coils also 

 varies with time, as 

 described on page 143, 

 /' may l>e considered as 

 being a time vector. 

 /. ' is also a time vector, 

 just as /and E are time 

 vectors, so that it may 

 be combined with them 

 also. Hence, E' and F 

 onn<-ctin<r links De- 

 ri the apace diagram 



of mint's. ;tnd the lime I-'LJ. 149. Relation of indu.vd i ranee to 



: M , of current* and ;;| i t ;; r: i """ f - "" rr "" f ****** ' 



voltages. Therefore, the 



space and the time diagram- may be combined into the one 



148. 



When the current Iau> the induced electromotive force by 90, 

 imaturc reaction i< in evi.-t opposition to the resultant 

 field. (See |-'ijr. 140, patfo 135.) Figure 1 l!> BQOWfl the vector 

 for I ditiori. The current / la^s the induced 



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