Kinsley — Discussion of Series Dynamo-Electric Machines. 109 



An examination of the characteristic of a dynamo, such as 

 is given in fig. 1,* suggests that it may be a part of an hyper- 

 bola. (See also figs. 10 and 12.) Since the total induced 

 electromotive-force is directly proportional to the speed when 

 the current is constant, see figs. 9 and 11, we can unite these 

 two conditions and obtain the characteristic surface of the series 

 dynamo. In fact fig. 2 shows how the surface may be built 

 up by connecting together a large number of the straight 

 lines. 



Current 



C" 



0' G 



Fig. 2 



Series Dynamo Surface. 



The line DB of fig. 2 is the characteristic of the machine 

 at the speed AD. The lines CB, C'B', etc., give the rela- 

 tions between E. M. F. and speed when the current has the 

 constant values AC, AC, etc. In this way the characteristic 

 surface can be defined by the actual tests of the d}^namo or 

 motor. 



* The curve shown is the same that was gotten from a Weston dynamo 

 using the armature and fields in series. The scales bave been changed for 

 eonvenience. 



