Potentiometer on Alternate Current Circuits. 



;05 



made with the writer's phase-shifting transformer, however *, 

 the accuracy of the phase-variation was found to be so good 

 that it was thought worth while to introduce it into potentio- 

 meter work; and fig. 2 shows the diagram of the connexions 



LOW RESJST.HNCE. 



which have been employed. The phase-shifter is here shown 

 supplied with single phase current through a phase-splitting 

 device, which can be built up with it so that it merely 

 requires connecting straight on to the mains. The current 

 derived from the secondary of this transformer traverses the 

 rheostat coils, and slide-wire of an ordinary potentiometer, 

 such as the Oompton form : and also some form of dyna- 

 mometer-current measuring device. The writer has found 

 a Weston A. C. colt meter excellent for this purpose, as it 

 gives a very good reading with the current ("05 ampere) 

 employed with the Crompton potentiometer. The remainder 

 of the potentiometer is connected up precisely as for ordinary 

 * ' Electrician,' Dec. 11, 1908. 



