Electromagnetic processes in traction supply system of 2×25 kV with catenary supports disconnected from the railway track

Abstract

The article explains the possibility of refusal of application of catenary supports of railway track for grounding and use an artificial grounding conductor for this purpose. The Artificial Grounding Conductor (AGC) consists of two metal strips located in the earth on which surface there are cable lines, metal covers of which are grounded on these strips through 1,2 - 1,5 km, but not closer than 200 m from places of connection of the grounding wires to them. Metal strips on traction substations or at the autotransformer points (AP), and also in the middle between two next AP are connected to a railway track or to the center tap of specially installed track impedance bond between APs. When connecting a cable of group grounding with fittings of catenary support it is possible to refuse AGC grounding to track impedance bond. It is noted that when calculating short-circuit currents between adjacent autotransformers, as well as in determining the input resistance of the electric traction network of 2 × 25 kV with a small inaccuracy it is possible to take into account only these autotransformers and neglecting shunt action of other autotransformers. It is shown that in the place of short-circuit the voltage of the artificial grounding conductor - earth system (railway track - the earth) has a maximum point on each autotransformer section. With distance from the first section from substation the value of this voltage decreases slightly and for the next section differs in 10 - 15 %. In the place of connection of AGC to railway track this voltage decreases approximately up to 30 - 40 %. Efficiency of use of the offered grounding system for sections with the supports disconnected from railway tracks, as well as for grounding of metal barriers of station platforms and metal barriers of railway tracks is established.