a Shunt- Transformer. 



133 



which part of the current flows. If the^impedance of A is 

 equal to that of B, then P.D. at terminals of A, V OJ and P.D. 

 at terminals of B, Y b , are equal. If A and B are alike in 

 resistance and self-induction, then V a and Y b would be in the 

 same phase and each equal to ^ Y. If curve (fig. 2) 



Fig. 2. 



represents V, then curve 1111 represents \ V. But if A 

 has large resistance and B much self-induction, then, although 

 V a may be still equal to Y b , Y a will be lagged and Y b accele- 

 rated. Then curve 3 3 3 3 will represent V OJ and 444 4 Y b . 



We have also two similar sets of lamps, L a and L b (fio-. 1) 

 in series between the two main leads. Under ordinary cir- 

 cumstances they would each have a P.D. of ^ V (curve 1111 

 fig. 2) at their terminals. But if we connect the junctions of 

 the two sets of lamps with the junction of the two resistances 

 then lamp L a will have P.D. Y a , and lamp L b a P.D. Y b ; and 

 therefore both lamps will become brighter. If the lamps take 

 an appreciable current, then, when the junctions of the different 

 circuits are joined, the current in the inductive resistance as 

 well as in the lamps becomes greater, but that in the main 

 circuit becomes smaller, as may be seen by a dynamometer. 



The resistance A may of course consist of lamps, and B 

 may be a choking coil, which absorbs very little energy. 



Prof. Ayrton has given this inductive part of the circuit the 

 name of a " Shunt-Transformer." 



I have made a similar experiment with one of Mr. Mordey's 

 transformers wound with three coils, each having the same 

 number of turns. Using one of these as a primary and the 

 other two^ as two independent secondaries, then, by having 

 one circuit comparatively non-inductive and the other in- 

 ductive, one gets the arithmetic sum of the amplitudes of the 

 secondary currents greater than that of the primary current, 

 although of course the vector sum must be less. For instance, 

 take one particular experiment. The primary was on a cir- 

 cuit having a P.D. of 128 volts. One secondary, A, was 

 composed of lamps, and the other, B, was a Tesla motor. 



