SWITCHBOARDS AND SWITCHBOARD APPLIANCES. 343 



tion, then, if the points T and T 1 do not touch, the relay is 

 excited, the contact C is open, and the exciter voltage decreases 

 thus causing the plunger to rise until the points T and T 1 

 come into contact. The moment this contact occurs, the relay 



4 



to terminals of field 

 rheostat of exciter 



I J 



to exciter 

 bus bars 



to exciter 

 bus ban 



to potential 

 transformer 



Fig. 297. 



loses its excitation, the contact C closes, and the exciter voltage 

 rises very slightly and at once separates the points T and T 1 '. 

 This separation of the points T and T f is followed by a slight 

 drop of exciter voltage which quickly brings the points T and 



