Kinsley — Discussion of Series Dynamo- Electric Machines. 119 



It is occasionally desirable in actual practice to operate one 

 series motor as the only load of a series dynamo. Usually 

 then it is essential that the motor regulate for constant speed 

 with widely varying loads. 



If it was desirable to run a motor whose characteristic was 

 as given b}' DU of fig. 8, — data, p. 121 the necessary con- 

 ditions could be gotten as follows: — 



The motor characteristic is drawn on the Ei plane of fig. 

 8, without reference to the speed axis. 



In this case the motor constants are 



a'=0.0067 

 6'=0.0066 



determined when the motor speed (n') was 1000 rev. pr. min. 



The motor characteristic equation is therefore 



(17) E. = ^ , ^,. and since 



* 1 + 6 I 



(18) E = E.+ R, = ^^=j^ + Ri 



This can be arranged 



(18) ^ -"i "' +g 



^ ^ 1 + 6i '" n 1 + 6'i ^ u 



If the desired conditions that n', n, and R be constant, for 

 varying loads and consequently varying current, are possible 

 with the above dynamo and motor a plot of 



and 



1 + 6i ^ 



will give a straight line. 

 Through what range of current the above conditions are 



