ALTERNATING-CURRENT TRANSFORMER. 



y 

 0, = . A very useful way of defining <t>i and <j> t is that of A. 



P\ 

 Heyland, who writes, 



*! = '' -*V 



Here TJ is obviously the magnetic conductivity or reluctivity of 

 the leakage-path. 

 Similarly he writes, 



6 l = r, . X^ 

 According to the notation which I have used in the preceding 



_ 



chapters, we define ^ and 0, by saying that A G = *-, and 



~0~A' = 



v\ _ 



141. If G mo\*es in the circle O\, C, which divides A G in the ratio 



A C : A G :: Vt : I, also moves in a circle, which is determined by C' 

 dividing O A in the ratio AC' : O A : : v : I. 



142. It is just as simple to find the locus of the primary flux Fi, 

 since, by our assumption, the primary current is constant, the leakage- 

 field 0i is also constant. We have, therefore, only to transfer the semi- 

 circle Ot to Ot, Oi Ot being equal to lF or, to put it differently, O A : 

 U A' ::vi : i. 



143. The primary resistance can easily be taken into account a we 

 may imagine that the drop caused by the ohmic resistance is equiva- 

 lent to the e. m. f. produced by a magnetic field of constant magnitude, 

 lagging behind the current by 90 degs. This field is represented by 

 D~M. 



The locus of the primary field is, therefore, the semi-circle Ot, 

 O Ot being equal to D M. 



144. The potential at the terminals, necessary to drive a current 

 proportional to X, through the transformer, is proportional to O M. 



From O M, the potential at the terminals is calculated from the 

 formula 



100 e = k ~ z F io" volts, 



in which k is generally equal to 2.22, if s is the number of conduc- 

 tors, and equal to 4.44, if z is the number of convolutions. 



77 



