CHAPTER VIII 



ARMATURE REACTION IN SYNCHRONOUS 

 MACHINES 



46. Armature Reaction and Armature Reactance in a Syn- 

 chronous Machine. When a synchronous machine carries a load, 

 either as a generator or as a motor, the armature currents, being 

 sources of m.m.f., modify the flux created by the field coils, and 

 thus influence the performance of the machine. Fig. 36 shows an 



-4* Direction of Rotation MK 



Fio. 36 The flux distribution in a single-phase synchronous machine 



under load. 



instantaneous flux distribution in the simplest case of a H 

 phase alternator, with one slot per pole; the armature conductors 

 are marked a and />. \\ it h t lu directions of the armature and field 

 run-nits in.liratrd in the sketch, the flux is crowded toward the 

 right-hand tips of the poles. In mlrr to show this, imagine two 

 fictitious conductors a' and 6' with currents equal and opposite 



110 



