TRANSMISSION LINE PROBLEMS 



59 



It is often desirable to find the regulation of a line at the 

 supply end, that is, the per cent change in supply voltage 

 from full-load conditions to no-load conditions, when the 

 receiver voltage is kept constant. If the receiver voltage 

 is E, we have seen in the preceding paragraph that the full- 

 load supply voltage is equal to 



2 A 



and the no-load supply voltage is 



The per cent regulation at the supply end is 



E s E 0a 



E 8 



X ioo, 



and the regulation volts at the supply end are, thus 

 E. - E* = A +--A - 



as in equation 6, Table III. 



In the expression C +jD for current at the supply end, 

 the quantity C denotes the 

 component of current which is 

 in phase with the voltage E at 

 the other end of the line. We 

 can, however, find the com- 

 ponent of supply current which 

 is in phase with the supply 

 voltage, by first finding the k - 

 watts at the supply end. 



Let the supply voltage be 



E, = A +JB 



-A - 



Fig. n. 



