54 



station is in the charge of ordinary 

 attendants, who are not skilled electri- 

 cians or engineers, and hence the experi- 

 ment will succeed. 



It has now been shown how, by the 

 aid of certain diagrams, the behavior of 

 any type of alternator, as regards its 

 ability to run in parallel, can be ascer- 

 tained ; but. as the use of these diagrams 

 involves a certain amount of study, it 

 would be desirable if they could be 

 superseded— at least for ordinary prac- 

 tical work, where an approximate solu- 

 tion of such problems is quite sufficient 

 — by some more simple method. Such 

 a method is afforded by the use of the 

 characteristics of alternators. If a ma- 

 chine of that class be run at constant 

 speed on open circuit, and with different - 

 strengths of exciting current, different, 

 terminal electromotive forces are ob- 

 tained. A characteristic can then be 

 plotted, the abscissas of which represent 

 exciting power, whilst the ordinates 

 represent terminal electromotive force, 

 which in this case is the same as the 



