246 



ELEMENTS OF ELECTRICAL ENGINEERING. 



Figure 2 1 2 is a sketch of a core-type transformer showing the 

 dimensions which are to be used in equation (30) to give the 



leakage inductance, N 1 be- 

 ing the total number of turns 

 in both parts of the primary 

 coil, which parts are sup- 

 posed to be connected in 

 series with each other. 



120. Combination of simple 

 circuits which is equivalent 

 to a transformer delivering 

 current to a given secondary 

 receiving circuit. In Art. 

 I oo it is shown that an ideal 

 transformer delivering cur- 

 rent to a receiving circuit of 

 given resistance R and given 

 reactance X is equivalent 

 to a simple circuit of resist- 

 ance r and reactance x con- 

 nected directly to the supply 

 mains, where r=(A 77 / N") 2 R 

 Fig - 212< and x=(N'IN"JX. An 



actual transformer delivering current to a given receiving circuit 

 is equivalent to an ideal transformer combined with certain 

 simple circuits, and this combination in turn is equivalent to a 

 combination of simple circuits from which all transformer action 

 is eliminated. 



Figure 2 1 3 represents an actual transformer delivering current 

 to a given receiving circuit ; Fig. 214 represents a combination of 

 simple circuits with an ideal transformer, which combination is 

 equivalent to Fig. 213; and Fig. 215 represents a combination 

 of simple circuits which is equivalent to Fig. 213. In these 

 figures coP represents the leakage reactance of the transformer, 

 R' the resistance of the primary coil, R" the resistance of the 





