498 



Mr. W. DuddeU 



[Mny 17, 



This is what Dr. Goldschmidt calls the electrical method of trans- 

 ferring the currents from the rotor to the stator. He has also devised 

 a magnetic method which is simpler. Turning again to our two pole 

 machine whose stator is supplied with current at 100 frequency, there 

 will be induced in the rotor a current of 200 frequency. Now, if 

 the rotor be short-circuited there will be produced in it a rotating 

 field having 200 frequency, which will induce in the stator a current 



X 



^ww- 



\[ 



Fig. 7. — Goldschmidt's Alternator. 



having 300 frequency, which in turn can be short-circuited and will 

 induce in the rotor a current having 400 frequency, and so on. I 

 have spoken of the machine as if the rotating field w\as produced 

 by a three phase current. A single phase field may be looked ujion, 

 theoretically, as two rotating fields in opposite directions, one of 

 which will have no effect as far as we are concerned, and therefore a 

 single phase machine will do just as well. Further, it is not really 



