i.iKh^ii-R riii.iii-iioxy ox iih.ii ii.>i.i.h:e uses i5J 



llii.ii KKi\>riM V Ai II MA riuN oi I'i>\\i k I.im ■- 



Siiui- till' miM^lirrim-iil i>l tlu' .itlriHi.ition of ;i circilil (irdin.iriK 

 ri(|iiiri's that tlu- ririuit l)r uriuinali'd in its mitj^i- imped. hkc ' In 

 avoid rt-UfCtion i-UVrts, tlu- first step in deliTiiiiiiinK tlie altiiniation 

 of the power line was to measure its siirj^'e impedanre. After con- 

 sidering se\eral methods for measuring this impedance, a siil)sti(iiti(»«r 



Fig. I — Open Circuit iZ,) and Short Circuit (Z.) Iinpcdance as Measured at 

 Carrier Frequencies on a 110,000 \'olt I'owcr l.inc \1 Miles Long 



methml was adopted lx?causc of its simplicity and the rapidity with 

 which measurements could be made. This method depends upon the 

 fact that the apparent or measured impedance of a uniform line 

 terminated in its surge impedance is equal to that surge impedance 

 and it consists in terminating the line in a known resistance and 

 determining the value of current supplied to the line by an oscillator 



' Surge or characteristic impedance may be defined as the measured impedance of 

 a uniform line of infinite length or in the case of a finite line it may Ix; expressed 

 mathematically as Z = VZ„-„„ X 2,i,„,, 



