5-C] 



CIRCLE DIAGRAM. 



Circle Locus, 

 Primary 



that 7 , /H and /M are constant, and remain constant under all 

 loads. This would not be quite true in a transformer in which 

 the primary line voltage t (and 

 not Ep) is constant; the difference 

 in the two cases is very small. 



ii. Transformer Under Load. 

 The complete diagram for a 

 constant potential transformer un- 

 der non-inductive load is shown in 

 Fig. 3. This will be seen to be 

 exactly the same as Fig. 2, the 

 open-circuit diagram, with certain 

 additions. As in Fig. 2, we have 

 the electromotive forces Ep and 

 E$ opposite to each other in phase 

 and in quadrature with the con- 

 stant flux $. On open circuit, the 

 primary current 7 flows as al- 

 ready discussed. 



12. Secondary Quantities. 

 When the secondary circuit is 

 connected to a load, a secondary 

 current I 2 flows, the value of 

 which depends upon the load. 

 With non-inductive load, this 

 current would be in phase with 

 E$, if the transformer were 

 perfect. On account of leakage 

 reactance, X 2 , the current I 2 



I Circle Locus of 

 / Secondary Current 



FIG. 3. Complete diagram for 

 a transformer tinder non-induc- 

 tive load. When a current 7 2 

 flows in the secondary, a load 

 current 7< 2 ) flows in the pri- 

 mary, opposite in phase and of 

 equal ampere turns. 7 2 = 7 (2) X 

 ratio of turns. 



lags a little behind ES, as shown 

 in Fig. 3. It is to be kept in 

 mind that Fig. 3 and other diagrams here given are not at all to 

 scale, being exaggerated in order to show more clearly the rela- 

 tions between the various quantities. 



