. Electric traction and transmission engineering . transmission line are cosh () = cos () = cos 36° 6= () = sin () = The current at the generator end of the line may then beobtained from equation (3) of § 79 as ^^ = (57-8 - 3S-8i)(i-oo765 X + X ) + 577r^^^i J (+), + or Ig = ( - ) ( + ) + ( + ) ( + ) = - + (- + ) = + amperes, and the current from the generator per wire is
. Electric traction and transmission engineering . transmission line are cosh () = cos () = cos 36° 6= () = sin () = The current at the generator end of the line may then beobtained from equation (3) of § 79 as ^^ = (57-8 - 3S-8i)(i-oo765 X + X ) + 577r^^^i J (+), + or Ig = ( - ) ( + ) + ( + ) ( + ) = - + (- + ) = + amperes, and the current from the generator per wire is 246 TRACTION AND TRANSMISSION. Similarly the voltage at the generator end of the trans-mission line is ^. = (57-8 - )^^^|^^( +) + ( + j)= (57-8-35-8i) () (+) 10 + ( + 4-2ii) 10^= ( + 9-23i + 46-95 + 4-21 i) 10^ = 58,990 + i, and the voltage per single circuit to be impressed on theline in order to have 57,700 volts per phase at the receivingend is 60,490 volts. \. Fig. loi. The vector diagram, Fig. loi, exhibits the phase rela-tions of the voltages and currents at the ends of the is seen herefrom that the current at the generator endleads the voltage at the same place by the angle 55° 7 —12° 50, or 42° 17. The efficiency of transmission at full load is X 60,490 X cos (42° 17) 7. = , or per cent. TRANSMISSION LINES. 247 Since cosh yS = + , the voltage at thereceiving end on open circuit for the same impressed E, the generator end is ^ + 134407 , ^- = a8i42l^^:o73^ = 7335o + 9,9307, and the absolute value is 74,900 volts. Consequently thevoltage regulation of the transmission line for 85 per centpower factor is 73>900 - 57700 ^ Q, ^Q , — = , or per cent. 57700 The charging current per single circuit or per wire isobtained from equation (i) of § 80 as .X +\+ A = () (+ J)
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