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BELL SYSTEM TECHNICAL JOURNAL 



disturbances in neighboring communication circuits, and the question 

 of grounding the neutral, in whatever manner, or of leaving it isolated, 

 exists because of its bearing on the avoidance or limitation of such 

 power system disturbances. Thus a method of grounding the neutral, 

 or any other method of power system operation designed to limit the 

 extent or the severity of accidental disturbances, must necessarily 

 possess importance with respect to inductive effects in exposed com- 

 munication circuits. 



It does not seem necessary, therefore, to apologize for the discussion, 

 in the first section of the paper, of the behavior of the power system at 

 times of faults to earth. In this section, an explanation is given of 

 the principal characteristic effect of the reactor which differs in some 

 respects from that set forth by Petersen in the paper already referred 

 to. The matter of transient over-voltage on a non-grounded phase 

 is also examined in this section, and the bearing of these and the 

 earlier considerations on inductive effects is discussed. 



In the second section of the paper, the behavior of the power system 

 with reactor under normal operating conditions is discussed with 

 reference to noise and other inductive effects in neighboring com- 

 munication circuits. 



Effects with a Grounded Phase on 

 Power System 



THE 



1. Action of Coil in Suppressing Arcs to Ground 



Referring to Fig. 1, in which, and in the following discussion it is- 

 assumed that the three admittances to ground are equal, the ad- 

 mittance current through the fault from the two sound phases is 



Fig. 1 — Single-Phase System with Neutral Grounded Through Reactor. Admittances 

 to Ground Assumed Balanced 



