408 



ELECTRICAL ENGINEERING 



In Fig. 378 



E = voltage between lines at the receiving end = 60,000. 

 e = voltage between lines and neutral at the receiving end 

 = 60,000 

 V3 ' 



Generating 

 Station 





FIG. 378. Three-phase transmission line. 



E G = voltage between lines at the generating station. 

 CG = voltage between lines and neutral at generating station 

 Ee 



/ = load current in each conductor. 

 Ic = charging current in each conductor. 

 IG= current per conductor at the generating station. 

 y = \/g 2 + 6 2 = admittance of each phase of the receiving 



circuit. 



z = Vr 2 + x 2 = impedance of each conductor. 

 b c = capacity susceptance of each conductor to neutral which 

 is assumed to be concentrated at the centre of the line. 



Resistance per conductor at 20 C. is 

 10.35 X 5280 X 77 



r = 



= 16 ohms. 



426,000 X 0.62 



The conductivity of aluminum is taken as 62 per cent of that 

 of copper. 



Inductance of each conductor is 



L = | ^0.74 logio ~g + 0.0805^10- 3 1 77 = 0.14 henry, 



and the reactance is 



x = 2 TT/L = 2 X 3.14 X 60 X 0.14 = 53.5 ohms. 



