24 



Mr. W. M. Mordey on the Dynamo 



Experiments with a D 2 "Victoria " Shunt Motor at 

 Constant E.M.F. 

 Difference of 

 potential at 



Speed. 



Current. 



terminals. 



H.P.* 





975 



36-3 



140 



1-8 -] 



Curve A. 



965 



66-5 



v 



6-6 1 



Maximum speed- 



948 



97-1 



j> 



12-87 j 



variation 3 per 



945 



130-8 



j) 



16-3 I 



1 cent. 



680 



29 



100 



1 ^ 



1 Curve B. 



677 



61-4 



V 



4-8 | 



Maximum speed- 



675 



102 



» 



9-14| 



* variation 3 per 



660 



125 



» 



11-7 „ 



1 cent. 



Curves connecting Speed and Work of D 2 u Victoria " Shunt Motor. 

 With supply at constant difference of potential. 



vvv 



!§!■■ 



















800 











600 

 400 



























200 

 <£ 











1 

 ! 











H.P. 2 



10 



12 



14 



16 



At first it appeared that the counter electromotive force of 

 the motor was dependent neither on speed nor strength of field, 

 as the latter was constant and the former very nearly so, while 

 the current rose with the work ; but calculation showed that 

 this was not the case, indeed it could not be so. 



Let us call the counter electromotive force e, and the loss of 

 potential caused by the resistance of the armature e i9 and the 

 difference of potential at the terminals E. Then 



e-\-e 1 =E. 



* Including an unascertained loss in transmission. 



