186 ALTERNATING CURRENTS 



by multiplying by the ratio of transformation. (See Fig. 174.) 

 Assume that E 2 is ten times EI and that everything is to be drawn 

 on the basis of E 2 being equal in length to EI. In order that 

 E 2 may be represented by the same length of vector as EI, E z 



must be multiplied by j^- or by y^- 



IiXi is to the scale of EI. 



As I 2 X 2 is to the same scale as E 2) it likewise must be multi- 

 plied by -=rp That is, 



NI* 



JTT-) gives the secondary reactance drop one-tenth its 



actual value as it is reduced to the same basis as the primary 

 reactance drop and the emfs. EI, E 2 , etc. 



Substituting for 7 2 , /i \T^)> the above expression becomes 



Ni 



That is, the secondary reactance drop may be referred to the 

 primary side by multiplying the primary current into the sec- 

 ondary reactance X%, when multiplied by the ratio of primary to 

 secondary turns squared. 



The total reactance drop in the transformer, to primary scale, 

 becomes, 



7 Y 4- T ( Nl 

 1 1 A i + 1 1 ( YT 



where X i = *i + (~ X 2 (52) 



XQI is called the equivalent reactance of the transformer referred 

 to the primary side. Its use in determining the characteristics of 

 the transformer will be considered later. 



Likewise, the equivalent reactance referred to the secondary 

 side 



i (53) 



