342 



ELEMENTS OF ELECTRICAL ENGINEERING. 



A solenoid, called the D. C. solenoid, is supplied with current 

 from the exciter bus bars, and it acts upon a plunger P which 

 actuates the lever L. A set of springs (not shown in the figure) 

 are attached to the lever L and adjusted so that the lever moves 

 through a certain definite range when the voltage of the exciter 

 changes from its lowest value (amount required to give normal 



Type B Oil Circuit-breaker. (Switchboard Mounting Rear View.) 

 Fig. 296. 



voltage on the alternating-current generator at zero load) to its 

 highest value (amount required to give normal voltage on the 

 alternating-current generator at full load). 



Suppose the contact point T 1 to stand in a given fixed posi- 



