K FORMULAS 4OA 



regulation are obviated. Synchronous machinery, con- 

 sisting of either synchronous motors or generators, is 

 installed in the stations throughout the transmission 

 system in sufficient quantity to hold the voltage at a 

 constant value by controlling the amount of leading or 

 lagging current supplied to the line. This method will 

 probably come into considerable favor, for there seems to 

 be practically no limit to the extent of a transmission 

 system operated at constant voltage. 



The following problem outlines the method of calcula- 

 tion for such cases. 



A line 400 miles long has a substation at the middle, 

 200 miles from either end. A load of 10,000 Kw. is 

 taken at the receiver end of the line, and 8000 Kw. at 

 the substation. Find the power factor which is required 

 for these loads, in order that the voltage at the generator, 

 substation, and receiver end may be 110,000 volts, the 

 following data being given: 



Conductor, 250,000 c.m. copper cable, i4-foot spacing, 

 3-phase, 60 cycles, 



r = 0.2284, x 0.813. 



ist section of line, / = 200 miles. 

 By the K formulas, 



1000 X 10,000 

 P = - -=90.91; 



110,000 



Q is unknown; 



A = 110,000 9500 + 3910 + 160.3 Q 

 = 104,410+ 160.3 Q; 



