In calculating traction network impedances, the greatest difficulties arise due to the need to take into account mutual inductive couplings between different wires of the multiwire contact system, between the rails, between the wires and rails, and between the contact systems of different tracks. However, no matter how accurate the methods of accounting these couplings are, numerous assumptions and uncertainties result in impossibility to guarantee the calculation of these impedances with an error of less than 5-10%. In taking into account mutual inductive couplings, it is convenient to use a simplified method, in which, instead of considering each pair of conductors, an average dependence for each multiwire network as a whole or an average dependence between two networks are considered. This approach produces virtually no effect on the accuracy of determining the resulting traction network impedances, yet it dramatically simplifies the calculations. A multiwire network can be represented as a set of "conductor-ground" loops. Equations for determining the impedance of the resulting loops are given, in which multiwire contact or rail networks behave as a conductor. On the basis of such loops, it is possible to determine the inductively decoupled impedances of the contact and rail networks for single-track and double-track sections, which are used for drawing up a traction network equivalent circuit. In doing so, the current leak from rails to ground must be taken into account for a rail network, which can be performed by introducing a special coefficient for inductively decoupled rail network impedance. A methodology for calculating this coefficient is presented.

This article discusses the problem of improving the accuracy of determining the location of a short circuit in the AC railways traction networks. Finding a short circuit can take several hours. An urgent task is reducing the time to search for a fault location. The purpose of the study is to develop a method that increases the accuracy of determining the location of a short circuit in AC traction networks. The method is based on computer modeling of inhomogeneities in the structure of the traction network and the arc. The proposed method makes it possible to take into account the arc resistance. The method was tested on the traction network active section. The error of the method is 200-300 meters. The method can find practical application in the work of dispatchers.