Title: Earthing system efficacy and condition in 2x25 kV electrified railway: Impact on operational safety
Abstract: Electrified railway uses the rails as the return conductor for the current absorbed by the locomotives (traction current). Aurizon's electrified coal network uses the 2x25 kV system. The traction return current from the locomotives mainly flows through rails and earth wire back to the two autotransformers (ATs) the locomotive is located between. The ATs, which are bonded to the rails, redirect the current into the overhead line circuit, away from the rails and the earth. However, depending on the efficacy and condition of the earthing system, it also occurs that some of the traction current returns to the feeder station through the ballast/formation and mast foundations via the general mass of the earth (GME). This phenomenon may cause the potentials found on the rails between the two ATs to reach values that are unacceptable. This aspect of rail potential rise in relation to the earth return path is studied in this paper. The results of a set of measurements taken on a single line track within Aurizon's coal network are presented first together with a theoretical calculation of the rail potential rise, which is compared with the measurements taken. The variation of the rail to earth potential as a function of experimental local earthing arrangements is also presented.
Publication Year: 2016
Publication Date: 2016-01-01
Language: en
Type: article
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