A NEW GROUND FAULT PROTECTIVE RELAYING SCHEME FOR DC TRACTION POWER SUPPLY SYSTEM

초록

In urban rail transit systems, ground faults in the DC traction power supply system are currently detected by the potential relay, 64P. Though it detects the fault it cannot identify the faulted region and therefore the faulted region can not be isolated properly. It could results in power loss of the trains on the healthy regions and the safety of the passengers in the trains could be affected adversely. A new ground fault protective relay system that can identify the faulted region is presented in this paper. The new concept uses the current differential scheme and the permissive scheme to identify the faulted region correctly. But it has some problems in application. Problem arises in that while current differential scheme needs sufficient amount of current but there isn’t much ground fault current since DC power distribution system is ungrounded to prevent buried metal made device from corrosion. Installing a proper type of arrestor in series with the low resistance grounding resistor could solve this problem.