556 



ELECTRICAL EQUIPMENT 



case an overload in the latter will cause the field switch to trip, 

 thus killing the voltage of the generator. 



The operating mechanism of field rheostats depends on their 

 size which in turn governs their location. The smallest sizes, 



FIG. 346. Solenoid-operated Field Switch. 



up to about 25 amperes, can usually be mounted directly back 

 of the board, and it is only necessary to extend the shaft of the 

 rheostat and connect it directly to the handwheel on the front of 

 the panel. Concentric handwheel mechanisms are also very 



