2a 



REGULATION CHART II 



Copper Standard, and hard-drawn aluminum of 60.86% 

 conductivity, and allowing an increase of i% 

 in resistance for the effect of spiralling of the 

 wires in the cable. However, these resistance 

 points are placed on the chart for convenience 

 only, and are not essential. If other assump- 

 tions are made, or if other sizes of conductor 

 are used, all that is needed is to find the re- 

 sistance of the conductor per mile, and use the 

 corresponding resistance point on the chart Fi - 8 - Regular 

 to find "V." 



One of the most common problems in estimating new 

 projects is to determine the size of wire needed for any 

 given value of regulation, and the chart will be found 

 especially applicable to this work. "F" is first found from 

 the equation, 



T , _ % Reg'n X 2 

 100,000 K.V.A. Xl 



Then lay a straightedge through "F" and the point for 

 the spacing to be used, and the nearest size of conductor 

 can be seen, at a glance, on the resistance scale at the right. 

 The chart is quite as useful for finding the voltage drop, 

 or required size of conductor, for distribution lines a few 

 hundred feet long as it is for transmission lines many miles 

 long. 



PROBLEM A. 



Find, by means of the chart, the regulation and line drop for the 

 following set of conditions: 



Length of line 100 miles. 



Spacing 8 feet. 



Conductor No. 3 copper cable. 



Load (measured at receiver end) , 3000 K. V.A., 

 66,000 volts, 90% P.P., three phase, 60 cycles. 



