RECTIF1KKX: THE SYNCHRONOUS CONVERTER 349 



If the efficiency be r? and the power-factor P.F., the three-phase 

 line current 



_ 0.9437^ / 



13 ~ r, X P.F. 

 Four-phase: 

 At 100 per cent, efficiency and unity power-factor 



where I', is the voltage between adjacent lines and /2 is the four- 

 phase line current, Fig. 320. 



VI I 



2\/2 V* F 2 



2V2 V2 



= 0.707 / 



(80) 



_'0. Currents and voltages in a 4-phasc synchronou conx <-rt<-r armature. 



If the efficiency be 77 and the power-factor I\I 1 \, the four-phase 

 line current 



i - 707 ' 

 /s ~ , x /'./ . 



The six-phase system may be considered as composed of two 

 Y-eystems, or two delta systems, each having one-half the capac- 

 ity of the si x-phase system. iSee Par. !!'.. page 364.) l-'iLiun- 

 W2\ shows a six-phase doublr-Y connection in which the BUC- 

 phase voltages b<M nt lines and to neutral are l' 8 . A 



cum-nt /, flows in each line. As the six phases are all com 

 together a1 the n.-utral. this system may be split into two <-<|ual 

 Y-eystems. I-'ig. 321(6). each having Ke volts to neutral. Tho 

 output of each V -system at unity power-factor is 3F e / watte. 



