CHAPTER IV. 

 FORMULAS FOR SHORT LINES. 



THE effect of capacity is inappreciable with short lines 

 as it amounts to only ^ of i% for a line about 20 miles 

 long. Thus distribution lines and many short transmission 

 lines can be quite accurately calculated without considering 

 the line capacity at all. The formulas in Tables I and II, 

 pp. 1 8 and 20, enable one to solve many problems con- 

 nected with such lines. 



The formulas are divided into two groups, those in 

 Table I being used when all the particulars describing the 

 load, such as K.V.A., voltage and power factor, are speci- 

 fied at the receiver end. Table II is used when these par- 

 ticulars are specified at the supply end. 



One first finds the quantities P and Q or P 8 and Q s . These 

 are the values of in-phase current, and reactive or quadra- 

 ture current, at the point where the conditions are speci- 

 fied. It is to be noted that only values of current 

 expressed in total amperes are to be used in connection 

 with the formulas in this book. The number of amperes 

 per wire is never used in the calculations (except with 

 single phase lines), but if it is desired to be known, it 

 may be determined from the formulas at the bottom of 

 the tables. 



The next step is to find the quantities A and B, or F and 

 G. One is then ready to find the value of any of the ten 

 quantities, whose formulas are given in the tables. It 



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