42 CONSTANT-VOLTAGE TRANSMISSION 



value of a synchronous motor as a pressure regulator 

 both with and without hand adjustment. F. A. C. Per- 

 rine pointed out that Tirrill regulators might be used, 

 and further stated: "When we get away from the dif- 

 ficulty and the inaccuracy of hand regulation, we have 

 overcome the most serious objection that has been raised 

 in any of the discussions on the employment of the 

 synchronous condenser." 



About the same time, Dr. Steinmetz stated, in his 

 book on electrical engineering, the possibility of holding 

 the voltage of a transmission line constant by means of 

 synchronous motors, and he gave a formula for the 

 theoretical maximum power load of such a line, neglect- 

 ing electrostatic capacity. 



In February, 1911, R. A. Philip presented a paper 

 before the A. I. E. E., and called attention to the 

 theoretical possibilities of synchronous motors in aiding 

 the growth of net-works. He also described the circle 

 diagram of a constant-voltage line when the voltages 

 at both ends were equal, and when electrostatic capacity 

 was neglected. 



In the Proceedings of the A. I. E. E., October, 1912, 

 a description was given by P. M. Downing of the large 

 6o-cycle net-work of the Pacific Gas and Electric Com- 

 pany, in the district surrounding San Francisco. This 

 net- work consisted of 1,500 miles of 60,000- and 100,000- 

 volt lines. It was stated that in some of the cities of 

 this net-work, synchronous condensers, controlled auto- 

 matically, were installed solely for voltage-regulating 

 purposes. Steam turbo-generators, installed as re- 

 serves, were also used, running idle, for this purpose. 

 As a result, the voltage regulation was greatly improved. 



