[mcnattghton] 



ELECTRIC SERIES TRANSFORMERS 



193 



(9) 



(10) 



Case II. — Double Transient of Current. 



For this case 

 Let 



A 



- at 



^t 



Then 



dii = A 

 "at 



-at - ;St 

 - a e + j8 € 



Substituting these values in Equation (3) and writing the com 

 plete solution. 



' -at - /5t 



Rot 



(11) i, 



K e L. 



M Ni A 

 L, N, 



ae 



+ — 



- a + Rot -/3+ R. 



Ijo i-io 



(12) 



(1-3) i^ 



1 



And hence 



M Ni 



L, N 



fA 



- a i8 



- a + R2 - i8 +R^ 

 U L, 



— Rjt 

 € Lj- 



- at - /3 t 

 - ae /3e 



+ 



-a+R2 -iS + R2 



L, 



L, 



The relation of Primary and of Secondary Currents to time is 

 shown in Figure (3). The Primary Current is a Double, and the Second- 

 ary a Triple Exponential of Reversed Sign. Both are zero at zero 

 time and at infinity. 



It is interesting to note that (for the assumed values) at t = 21-6, 

 the secondary current reverses and is of the same sign as the Primary. 



