302 



Mr. W. Duddell on a 



curves for the alternator; and Curves II. are between B..M.S. 

 current and P.D. with constant exciting current at frequencies 

 of 15,000 and 10,000 — per second. 



Curves II. — Between P.D. and Current. High-Frequency Alternator. 



Constant Exciting Current=l ampere. Inductor with 30 teeth. 

 fair? 



38 





















2k 





















34 





















32 



\ 



















30 





\ 

















28 





















26 





















£4= . 









\*. 













ZZ 









X 2 













20 







^■^ ,< 



o 



\3» 











18 









^x 



v^; 











16 













\° 









14 











>c 











12 





















10 





















8 





















6 





















4 





















2 





















o 



•05 



1 



•t5 



2 



■25 



3 



35 



•4 



i5/7Mfffc 



/?oot Mean Squared Current 



Subsequently the inductor having 30 teeth with which the 

 above curves were obtained was replaced by inductors having 

 60 and 90 teeth, with which frequencies up to 50,000 ~ 

 per second were obtained. This high frequency being still 

 hardly sufficient to settle the question of the resistance of the 

 solid arc, some means for still further increasing it had to be 

 devised. 



As the highest speed of the inductor was only 600 revolutions 

 per second, whereas the limit at which it was considered safe 

 to run the inductor, owing to considerations of bursting, was 



