66 CONSTANT-VOLTAGE TRANSMISSION 



best economy and, it is believed, the best engineering. 

 A line or net- work with not only steady voltage, but equal 

 voltage at all points, may make use of the line construc- 

 tion and insulation more fully, but it will require a very 

 much larger capacity in synchronous phase modifiers, 

 and is, therefore, not so advisable, unless there are special 

 conditions such as the transmission of energy at times 

 in one direction along the line, and at times in the oppo- 

 site direction. 



In the comparisons, where one 3 -phase circuit is 

 mentioned, the comparison is made on a unit basis and 

 it is not lost sight of that, for an important transmission 

 project, it is inadvisable to use only one circuit. An 

 exception would be in the case of a net-work, where in 

 case of emergency the power could be transmitted by a 

 roundabout route through the net- work, or the necessary 

 power could be sent from some other source. It is for 

 this reason that net-works can be built of heavy con- 

 ductor, single circuit lines, which are especially economi- 

 cal when operated by the constant-voltage method. 



