REGULATION CHART 9 



load voltage when the load is thrown on or off, assuming 

 constant supply voltage. 



The total regulation is quickly figured on the slide rule 

 from the following formula for two-phase (four wire) or 

 three-phase lines: 



v , ,. , 7 1A 1000 K.V.A. X IV 

 Regulation Volts = - > 



E 



where K.V.A. = Kilovolt-amperes of load, at the receiver 



end. 



E = Line voltage at the load, or receiver end. 

 / = Length of line in miles. 



For single-phase lines use 2V instead of F, making the 

 formula as follows: 



1000 K.V.A. X / X 2 V 

 Regulation Volts = - -- 



E 



The regulation volts may be expressed as a percentage 

 of E to give the per cent regulation, and a formula is given 

 on the chart for obtaining this result directly. 



The line drop, or difference in voltage between the supply 

 end and the receiver end of the line, is the same as the 

 regulation for lines less than about 20 miles long, but for 

 longer lines the effect of the charging current must be taken 

 into account by the formula 



Line Drop = Regulation Volts - 



iooo/ 



where K = 2.16 for 60 cycles, 



and K = .375 for 25 cycles. 



It is seen that the voltage due to the charging current 

 is proportional to the line voltage E, and to the square 

 of the number of miles, but is independent of the size or 

 spacing of the conductors, within the assigned limit of ac- 

 curacy. The constant K does not need to be used in the 



