OPERATION OF SYNCHRONOUS MOTORS. HUNTING 127 



The explanation of the role of these dampers is made easy by 

 reference to the elementary considerations set forth on page n. When 

 there are no speed-oscillations, the armature-reaction flux undergoes 

 no displacement with respect to the field-poles, and, consequently, it 

 does not generate any induced E.M.F. in the damping circuits. On 



FIG. 61. 



contrary, any variation of speed producing a flux-oscillation 

 gives rise to eddy currents, which are all the stronger the greater the 

 conductivity of the damping circuits and the greater the extent to which 

 they increase the flux developed by the armature. The energy con- 

 sumed by the induced currents is what produces the damping. It 



FIG. 62. 



manifests itself by the production of a corrective torque exerted on the 

 armature and which tends to bring the speed to synchronism. 



The same explanation applies in the case of a single-phase motor, 

 with this difference, that the inverse revolving flux due to the armature 

 should, in consequence of its high velocity relatively to the damping 

 circuit, produce strong induced currents which almost completely 



