[mcnaughton] electric SERIES TRANSFORMERS 205 



The Curve marked Closed Circuit shows the relation of Volts 

 generated in the Secondary winding to Current flowing therein under 

 ordinary load conditions. The reading of Voltage is obtained by using 

 an open circuit auxiliary winding wound over the Secondary and of 

 the same number of turns. The Current is read directlj^ on the 

 Secondary ammeter. 



From these results the Phase Angle may be calculated, for any 

 Secondary Current, by substituting the corresponding value of Open 

 Circuit Impedence (which is approximately coL,.) into equation (30). 

 The Phase Angle so calculated is shown by the dotted curve of fig. 

 (9) . No allowances has here been made for the change of the effective 

 value of Resistance due to increased iron loss at the higher Flux 

 Densities. 



The ratio cannot be calculated on account of the unknown value 

 of M (the Mutual Inductance) in equation (32). 



Case IV. 



di, 

 (34) Let ij = constant. Then (35) ^ = t) 



and 



(36) 



M Nj o 



R,t l7 F, 



K £ L, D + R2 



- R, t 



and at t = o let ij = o hence K = o 



and 



ij = alwaj^s. 



That is there is no competent of Secondary current coi responding 

 to the Constant Primary Current. 



Figure (10) shows the effect on the Ratio and Phase Angle of a 

 Direct Current superimposed on the Primary Alternating Current. 

 The deformation and large Phase Shift of the Secondary wave ma)^ 

 be seen by comparison of Records No. 67 and No. 68. 



Figure (11) shows the effect on the Ratio and the Phase Angle 

 of a constant Direct Current for different values of alternating cur- 

 rent. Ratio and Phase Angle decrease with increase of Alternating 



