242 



ELEMENTS OF ELECTRICAL ENGINEERING. 



occupied by the primary coil, the part <J>" which depends upon 

 the flux which passes through the region occupied by the sec- 



Fig. 207. 



ondary coil, and <I> 

 the coils so that 



which is the actual flux passing between 

 s = <$>' + 3>" + $'" (ii) 



Figures 207 and 208 show side and end views of a shell-type 

 transformer of which the primary and secondary coils are not in- 



_ terleaved. The trend of the leakage 



^^~ "~""x. 



flux is shown by the dotted lines in 

 the upper part *of Fig. 208 (omitted 

 from the lower part of the figure for 

 the sake of clearness), and the dimen- 

 sions X, Y, g, X and / are to be 

 expressed in centimeters. Fig. 209 

 is an enlargement of the upper part of 

 Fig. 208. 



Consider the flux, dt, which 

 crosses the primary coil between the 

 dotted lines aa, Fig. 209 ; the com- 

 plete path of this flux, as indicated by the dotted line, encircles 

 a fractional part x\X of the primary turns N 1 of which the 



Fig. 208. 



