2 CONSTANT-VOLTAGE TRANSMISSION 



The valuable features of constant-voltage operation 

 by means of power-factor adjustments consist in more 

 than doubling the maximum power load of many existing 

 lines, thus making fewer or cheaper transmission lines 

 necessary for a given project. The voltage is con- 

 trolled at the receiving end, which is a much more 

 desirable place than at the supply end. The design of 

 transmission lines may be affected, and heavier con- 

 ductors, wider spacing, and higher reactance may be 

 used than are generally found practicable. The eco- 

 nomical distance of transmission is distinctly increased 

 by the constant-voltage method. The adoption of this 

 method of control for a transmission system will not 

 lessen its reliability. An item of very practical impor- 

 tance is that the method can be gradually adopted with- 

 out disturbing the normal operation. 



A power line, as ordinarily operated, has at some part 

 of its length a very noticeable variation in voltage from 

 hour to hour. This is often the most troublesome fea- 

 ture encountered in delivering a large power load. 

 Furthermore, since in most lines a steady voltage is 

 desired at the receiver end while the adjustments in 

 voltage must be made at the supply end where the 

 receiver voltage cannot be observed, it is often extremely 

 difficult to produce a satisfactorily steady voltage. 

 With a constant-voltage line, on the other hand, there 

 need be no voltage variation at either end, and it is far 

 easier to obtain a steady voltage as shown by a volt- 

 meter at any substation, because adjustments in voltage 

 are always made within sight of the voltmeter in ques- 

 tion. In other words, since steady voltage is required at 

 the receiver end of a transmission line, that is the rational 



