Contributions to Dynamometry . 351 



p — ye is the power heating transformer and secondary, 



pry 2 is the power heating the secondaiy ; 



•*• p — yc — py 2 is the power heating the core, heing the 



result of hysteresis and Foucault currents. 



Multiply E by C, and we have the total power, which is 



R.C 2 + rCc + -p.Cy. 



n ' ' 



Thus the whole power consumed in such a system may be 

 measured by means of three dynamometers judiciously applied 

 to the main current and those in a single branch. 



This, of course, can be applied to measure the power at 

 work in a system of parallel transformers by means of a home 

 transformer, whose resistances may be kept fixed or at least 

 accurately determined. 



It may also be used to measure the electric power of a 

 welding transformer, into whose secondary it is inexpedient, 

 if not impossible, to introduce any extra resistance. 



In this case a very high power would be rendered mea- 

 surable by increasing the resistances in the circuits of the 

 parallel sj'stem. The power consumed in the parallel system 

 being, as indicated, known, can be deducted from the total. 



Transformers in Series. 

 Let E be the E.M.F. of the machine ; 

 r, be the resistance of the 1st primary ; 

 r 2 „ „ 1st secondary and 2nd primary; 



r s „ „ 2nd „ 3rd „ 



N x be the magnetic lines in 1st core ; 

 N 2 „ „ 2nd „ 



m 



1 



} = turas in { secondaiy } of Ut tra »sformer ; 



r 



c x = current in 1st section ; 

 c 2 = „ 2nd „ 



Then „ d^ l 



&c, &c. 



