16 Proceedings of the Royal Society of Victoria. 



8in<p +X.y . 

 tan X= p; Ffj— (q.p.) 



where a and tt + A are the angles that C^ and C^ are behind Ej in 

 phase respectively, and tt — /S is the angle C^ is behind Cj. 

 If TT+e be the angle Ej is behind E^ in phase, then 



ana tane= q— — 

 1 +/>v 



a small quantity of the first order, so that Ej and E^ are always 

 approximately in opposite phases. 



Obviously all the above formulae will apply to non-inductive 

 loads when cp is made zero in them. 



20. The pressure drop at the secondary terminals from no 

 load to any value of the load can now be expressed in terms of 

 the load, its power factor, the transformer numerics and the 

 leakage coefficients as follows : — 

 We have (see § 19) 



hind- 



so that 



E, (at load given by^') 1 



Ej (at no load) Dq 



1 



"^ Do(l+;CiCosS + ^^) 



l+/.j' + i(4/ + ^V 



= l-/r-i(2/ + ^V 

 and the percentage drop for any load given hj y 



= l00j\p + hJ2p' + f)y]. 



Remembering the values of j> and ^ (§18) we see that the 

 drop depends on the sum of the reciprocals of the transformer 

 numerics (t e. on T) and on the sum of the leakage coefficients. 

 We also see that for non-inductive loads the leakage effect on the 

 drop is only a second-order term, while for inductive loads it is a 

 first-order term, thus showing how important it is to have a small 

 leakage in a transformer that has to operate inductive loads. 



21. If the transformer were so designed that at full load it 

 works with maximum efficiency, then the full load value of y or 



