328 



THE ROTARY CONVERTER. 



curve corresponding to a definite value of the alternating- 

 current output. 



Fig. 163 shows a set of six curves obtained on the 

 same machine as that employed for the result shown in 

 the previous Figs., 159-162. 



The direct voltage applied was maintained constant at 

 100, so that the alternating voltage gives directly its 

 percentage value in terms of the direct voltage. 



FIG. 163. ROTARY CONVERTER DRIVEN FROM D.C. SIDE. 

 BETWEEN A.C. Volts AND EXCITATION. 



RELATION 



It will be seen that there is one value of the excitation 

 which gives the maximum ratio of voltage-conversion, and 

 further, that this value varies for different values of the 

 load. The inclined dotted line passes through the max- 

 imum point of each curve, and shows the variation of 

 exciting current which would be necessary in order that 

 the converter should give the maximum voltage ratio for 

 varying loads. 



