574 



ELECTRICAL MEASUREMENTS 



switches, etc., and which rise to values much higher than those for 

 which the transformer was designed are not correctly reproduced. 

 Fig. 353 shows the results of measurements of the magnetizing 

 and the power components of the exciting current, 7 , made by 

 use of a quadrature dynamometer. 13 The tests were made at 25 

 and 60 cycles on the current transformer to which the data 



0.71 



at 25 Cycles per Second 



at 60 Oyclei per Second 



20 40 60 80 



% Bated Full Load Current 



FIG. 353. Showing components of total exciting current in current 



transformer. 



given below apply, and Fig. 354 shows how well calculations 

 based on these results agree with direct measurements of the 

 ratio and phase angle. 



In order to give an idea of the magnitude of the quantities 

 involved, reference may be made to the following data which 

 pertain to the current transformer whose characteristics are given 

 in Figs. 353 and 354: 



Nominal ratio = -^ = - 



Primary turns 

 Secondary turns 



i = 25. 

 i = 196. 



