Alternate Current Transformer. 49* 





VII. 



(d) Substituting the values for L',^, L'i,M'i.2, M'.i, in V., VI., 

 and VII. in the expressions for x'^ and x\ in § 43 we find 



I. If the two extreme sections in the window are even ones, 

 in which case j^i— 1, that 



"•^=-3^)1 ^•^+7-^^)' 



, , _87r/3' H 



where H =/7;o + (/— 1 )b^ 



= total height of window. 



II. If the two extreme sections in the window are odd ones, in 

 which case /=/+l, 



^'^-3o^i-+ r'y 



47r/37/-l \ 



^^"i=-3^l-+l'^^+M 



(c'). From the results in (d) we see 



I. That the coefficient x' <^ or x\ of the coil to which the two 

 extreme sections belong is negative, indicating that this part 

 of the leakage produces on the coil, with the extreme sections, a 

 capacity and not an inductive effect. 



The same thing is true with regard to the coefficients x'o, and 

 x\ due to the leakage lines that do not cross the windows and 

 which will be determined in the next paragraph, and it has been 

 pointed out in § 29 that secondary leakage reduces the efficiency 

 of tlie transformer when operating inductive loads, hence the 

 winding of a shell transformer for inductive work should be so 

 arranged that the two extreme sections belong to the secondary 

 or output cod. 



