SUMMARY
It has been proposed to use power losses as an additional energy parameter to complement basic energy indicators in determining the short circuit mode in a traction power grid. Three techniques have been reported to determine the transitional characteristics of an electrical network, which are based on methods of approximation, discrete electrical engineering, and spectral analysis. The need to construct these methods is predetermined by the non-stationarity and nonlinearity of electrical parameters for traction networks, which could form uncertainty in the moment of a short circuit occurrence.The input data to determine the energy characteristics and losses are the functions of transitional voltage and transitional current, measured at the clamps of the switchgear to which power conductors of the traction network are connected. Based on the experimental measurements and the reported methods, we have calculated basic energy parameters of the network, as well as losses, at different short circuits.Results of our calculations show that during short circuits in a traction network the quantitative values of energy indicators and unproductive losses make it possible to unambiguously assess the mode of network operation. The obtained results also make it possible to determine the actual load on protective switching devices at short circuits in a traction network.The proposed methods could be applied when developing computer models of traction networks in order to study them and perform engineering calculations. They could also be applied while designing new or reconstructing current DS traction networks, in order to more accurately substantiate design solutions. In addition, the proposed methods could be employed when constructing new or improving the existing samples of protective switching equipment