GENERAL DIAGRAMS FOR SYNCHRONOUS MOTORS 175 



watts equal, the induced E.M.F., as a function of the reduction- 

 coefficient k, due to overlapping, may be expressed thus: 



(d) 



27tk _ 



" 



in which T= the periodic time, 

 and $=the magnetic flux. 



From this, we have 



Substituting in (c) we have 



\/2 



I have shown elsewhere (see Properties of Revolving Magnetic 



k 



Fields, Eclairage Electrique, 1895) that the ratio is substantially 



K 



equal to I ) . We therefore have 



32 3 2 



This close approach of the value of to unity shows that the trans- 

 verse reaction is practically negligible in comparison with the direct 

 reaction. Hence rotary 

 converters may be treated, 

 practically, as if there were 

 no transverse reaction in 

 them. 



If the internal losses 

 are taken into account, the 

 secondary (output) watts 

 will be from 10 to 15 per 

 cent less than the primary P IG 



(input) watts; and the 

 ratio t, will be still less near unity. Nevertheless it is found that: 



i. The direct-current E.M.F. undergoes no modification in con- 

 sequence of the transverse reaction, because the brushes always remain 



M.m.f of Watf.'sx 



Current Reaction 



ff.mj of exc/tof/or? 



