CURRENT-LIMITING REACTORS 



481 



the subject the reader is referred to an article in the " General 

 Electric Review " of June, 1917, by W.W. Lewis, entitled " Short- 

 Circuit Currents on Grounded Neutral Systems." 



Referring to Fig. 298 : Let G represent a generator, T\ a trans- 

 former with high voltage winding connected in Y and neutral 



A V y 



FIG. 298. Single-phase Short Circuits. 



grounded; Tz a transformer stepping down the voltage for the 

 load L. The ohmic reactance of the generator is represented by 

 x\\ of the step-down transformer by x 2 ; of the grounded trans- 

 former by z; of the portions of line from transformer to the point 

 A by 7/1 and 1/2, and of the total length of line by y. E is the normal 

 high-tension voltage. All reactances, etc., are expressed in terms 

 of their high-voltage equivalents. 



Assume a ground at A. Then currents will flow as indicated 

 by the arrows. The value of the current is expressed by the fol- 

 lowing equation: 



.5770 



or expressed in per cent reactance based on the normal three- 

 phase line current / 



1007 



i 



per cent /xi+per cent 7?/i+per cent Iz 



Now consider the arrangement of Fig. 299, i.e., ungrounded 

 transformer T\ at the generating end and transformer T 2 with 

 grounded neutral at the load end. The short-circuit current will 

 flow, as indicated by the arrows. The delta winding of trans- 

 former T 2 serves to cause equal in-phase currents to flow in each 



