CONSTANT-VOLTAGE TRANSMISSION 

 CHAPTER I 



INTRODUCTION 



THE new system of constant- voltage transmission has 

 been successfully applied to both large and small power 

 projects, and the results thereby obtained demonstrate 

 convincingly that this method must be closely in- 

 vestigated by those responsible for the management or 

 design of electric-power projects. The advantages of 

 synchronous motors for raising the power-factor of the 

 load of a steam-driven station have been thoroughly de- 

 scribed. It is, however, not so well known that synchro- 

 nous motors are of far greater value with long-distance 

 transmission systems than with local power systems, so 

 much so, in fact, that synchronous motors can often be 

 installed to run idle, and yet save several times their cost. 



The constant-voltage method depends on the use of 

 synchronous motors, or phase modifiers, in large quan- 

 tities in the receiving substations. The excitation of 

 these machines is continually changed, either by hand 

 control or by automatic regulators such as the Tirrill 

 regulator, and by thus changing the power-factor, the 

 voltage drop in the transmission line is held at a constant 

 value. In this way voltage variation on the trans- 

 mission line is eliminated, and this result is so valuable 

 that the advantage of the synchronous machines for 

 raising the load power-factor, while it exists, is by 

 comparison, of secondary importance. 



1 



