14 TRANSMISSION LINE FORMULAS 



PROBLEMS, CHAPTER III. 



(REGULATION CHART.) 



1. Find the size of copper cable which is needed to deliver 200 

 K.V.A. a.t a distance of 3 miles with 10% drop or less. 



Spacing of line 2 feet. 



Character of load (at receiver end), 2200 volts, 

 80% P.F., three phase, 60 cycles. 



[Ans. No. o.] 



2. Assuming No. o copper cable for the previous problem, find 

 the volts drop in the line. 



[Ans. 219 volts. Calculated, 221 volts (Chap. IV., Prob. i). 

 Error 0.1% of line voltage.] 



3. Find the size of copper required for a drop of 6% or less in the 

 following case: 



Length of line 5000 feet. 



Spacing 18 inches. 



Load (at receiver end), 75 Kw. (79 K.V.A.), 

 95% P.F., 2000 volts, single phase, 60 cycles. 



[Ans. No. 4 copper.] 



4. Assuming No. 4 copper wire of 1.312 ohms per mile, find the 

 per cent line drop and the supply voltage. (See Elec. Journal, Apr., 

 1907, p. 231.) 



[Ans. 5.43%, 2 1 10 volts, calc. 5.43%, 2109 volts (Chap. IV., 

 Prob. 3).] 



5. Find the required size of copper for 9% regulation in the fol- 

 lowing case : 



Length of line 25 miles. 



Spacing 3 feet. 



Load (at receiver end), 2500 K.V.A., 



20,000 volts, 60% P.F., three phase, 25 cycles. 



[Ans. No. o copper.] 



6. Assuming No. o copper wire of 0.520 ohm per mile, find the 

 per cent regulation. (See Elec. Journal, Apr., 1907, p. 231.) 



[Ans. 8.42%, calc. 8.51% (Chap. IV, Prob. 5). Error 0.09% 

 of line voltage.] 



