CHAPTER XIV. 



CAPACITY OF TWO-PHASE AND THREE-PHASE LINES. 



Capacity, Two-phase. The charging current of a single- 

 phase line was shown in Chapter XIII to be 



amperes per mile of line 



where b is the tabulated value of capacity susceptance per 

 mile. 



In a two-phase, four-wire line, each phase is quite similar 

 to a single-phase line, and so the charging current per wire 



is 



%Eb. 



As this amount of charging current flows in each phase, 

 the total amperes of charging current are 



Eb, 



for a two-phase, four-wire line. 



Capacity, Three-phase, Irregular Spacing. When the 

 wires of a three-phase transmission line are not spaced at 

 the corners of an equilateral triangle, but the transposi- 

 tion of the conductors is carried out at regular intervals, 

 the charging current in the wires will be a balanced, three- 

 phase current, since each wire will have passed through the 

 same average conditions. This is shown in an approxi- 

 mate manner as follows: 



93 



