Dynamo-electric Machines. 287 



i+ r - 



U + r 



P 



R+^- R,(l+-)+v 



R+r ( 1+ ?) 



R + rs' 



T> 



where s=l -\ , and is a little greater than unity. 



E.M.F. 

 E = total E.M.F., e between armature terminals. 



e=^-E 



R + 



r 



R + rs 



Current. 



E. 



c 



in main coils 



e 

 r 

 E r 



r R + r 



E 



" R + rs> 



c 



in shunt coils 



_ ^ 



r E 



p R + rs 





Current- turns =N. 





nC + vc 



=N, 



( . 



v \ E 



= FE, 



