208 TREATISE ON ALTERNATING CURRENTS. 



converter to that of the same machine giving the same output as 

 a continuous- current machine is 



8 



For a tri-phase rotary converter this ratio is 0'555, that is, a 

 tri-phase rotary is, neglecting friction and iron losses, capable of 

 giving 80 per cent, greater output for the same heating of the 

 armature than the same machine used as a direct - current 

 generator. 



If the power factor is cos 0, equation (1) becomes 



n = /i sin (pt + $ - 0) (7) 



the current being a leading one, and the mean square current 

 now is 



8 16 .8 tan 2 



< Y\ 



o o *^ I 



n 2 sin 2 ) 



(8) 



In the case of unit power factor, = 0, and equation (8) 

 becomes the same as equation (6). 



