146 COMMERCIAL ELECTRICAL TESTING 



Wl+ 



Then electrical efficiency = T . T 



Wm 



where CT is the mechanical losses in L and M and the 

 belt loss. 



For Case B 



. Wl+C 2 R + CT r -. 



Efficiency = ^ where C T is the mechanical 



losses of L, including belt loss. 



In running the counter torque curves, the field of L 

 must be held constant throughout and readings must 

 not be taken when accelerating. 



