CHAPTER III. 

 REGULATION CHART. 



THE characteristic of a transmission line which limits 

 the load it may carry is its regulation, or the variation in 

 voltage which occurs when the load is thrown on and off. 

 This is especially true when the load has a low power 

 factor, which is the case in most instances at the present 

 time. 



For estimating the regulation of a line, or the size of 

 conductor required, the regulation chart which forms the 

 frontispiece of the book may be used, and it will give the 

 required result much quicker than any method of calcula- 

 tion. An extra copy of the chart is inserted at the back 

 of the book; it may be found useful for cutting out and 

 mounting on cardboard. 



The chart is accurate within approximately J of i% of 

 full line voltage, when the regulation is less than 10% and 

 the line is not more than 100 miles long. 



In using the chart,* one places a straightedge across it 

 from the point on the left corresponding to the spacing of 

 the transmission line, to the point on the right, correspond- 

 ing to the resistance ,of the conductor per mile. The reg- 

 ulation voltage, V, per total ampere per mile of line, is 

 then read directly from the chart for the power factor of 

 load considered. The regulation is taken as the change in 



, * The process of using the chart is similar to that used with the trans- 

 former regulation and efficiency charts published by J. F. Peters, Electric 

 Journal, December, 1911. 



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