564 



ELECTRICAL MEASUREMENTS 



Different designs of this instrument are shown in Fig. 346. 



Transformer A is for use on installations of from 2,500 to 15,000 

 volts. The distance between the primary and the secondary 

 terminals and frame is to be noted. Transformer B is a portable 



B 



FIG. 346. Current transformers, General Electric Co. 



instrument designed for general testing purposes. The ratio is 

 variable, for the primary is formed by thrusting a flexible cable 

 through the central opening, the number of primary turns being 

 thus readily altered. Transformer C has its iron core made in 



