5-C] 



CIRCLE DIAGRAM. 



,8 7 



in which all quantities are expressed in terms* of the primary. 

 This will be most readily understood by treating the transformer 

 as a "level" (1:1) transformer; we have then, Ep = E$; and 



/ (2) =/ 2 . 



The diagram corresponding to Fig. 6 is shown in Fig. 7 and 

 is seen to be the same as Fig. 3 with all secondary quantities 

 expressed in terms of the pri- 

 mary and drawn in the first 

 quadrant. 



21. Simplified Circuits. 

 The equivalent circuits so far 

 considered (Figs. 5 and 6) 

 and the corresponding diagrams 

 (Figs. 3 and 7) are prac- 

 tically exact and may be used 

 for the accurate solution of any 

 transformer problem. It will 

 be noted that the resistance 

 and reactance for the two wind- 

 ings are treated separately, 

 RiXi in the primary and R 2 X 2 

 in the secondary. By com- 

 bining these into a single equiv- 

 alent R and X, the trans- 

 former circuits can, with little error, be simplified in either of 

 two ways: 



.*(2oa). To express secondary quantities in terms of the primary: 

 multiply current by (Sz-i-Si) ; multiply voltage by (Si-+-S 2 } ; multiply X 

 and R by (Si -r-Sa) 2 . See i6a, Exp. 5-B. It will be understood that 

 secondary quantities thus represented in the primary are not the real 

 secondary quantities but the equivalent primary quantities which could 

 produce the same results ; thus, in a 10 : i transformer, i ohm in the 

 primary is equivalent to o.oi ohm in the secondary. 



To express primary quantities in terms of the secondary, divide instead 

 of multiply by these factors. 



Fluxjfr 



FIG. 7. Exact diagram as level 

 transformer, corresponding to Fig. 6. 

 The same as Fig. 3 with secondary 

 quantities expressed in terms of the 

 primary. 



