86 Scientific Proceedings^ Royal Dublin Society. 



(5) Determination of corona loss. 



J = 0-83 for 19/U cable. 

 g = 1-02. 

 Vc = 123,400 X -83 X 1-02 x -2 x 2-78 = 58,000. 



q\ 5-53 X ^^ X -^. X (62,600 - 58,000)2 ^ IQ-'' = 46,800 watts 

 1'02 24'o 



= 46-8 kw. 

 We now revise the efficiency estimate. The approximate total power put in is 



2,970 + 47 = 3,017. 



" = 3,or7 = ^^^- 



18. As a further example we will assume a still higher voltage, with a view to 

 illustrating the great increase in corona loss at high voltages. 



Data as in paragraph 15, but let the voltage between wires at the receiving 

 end be 132,000 volts, and the spacing between conductors be 120 inches. 



(2) For the same power delivered, the effective mean current per phase is now 

 (see paragraph 13) halved, or C" = 15-5 amps. 



The most economic size is then 



A' = -00392 X 15-5 = -061 sq. inch. 

 Choose conductor 7/12 having A = -0606 sq. inch. .-. re = -156 inch. 



(3) Ccdcidation of line constants. 



A 



a = -156, b = 120, - = 770. 



log,o^^ = 2-89. 



L = (8 + 74-1 X 2-89) x 10"' = 2'22 x 10"'. 

 ^=5 X 10-». 



^= 27r X 50 = 314-16. 

 pL = -699. 

 pS = 4-23 X 10-^ 

 m = v/('71 + i X -699) (5 x lO"" + * x 4-23 x lO""). 



= y - 2-96 + 1x3-01 X 10-3 = -000794 + i x -00189. 



I -71 + ^ X -699 



yjb X 10-' + i X 4-23 x 



10- 



= v/"165 - i X -168 X 10^ = 448 - ^ x 188. 



