On the issue of increasing operational energy efficiency of eight-axle passenger DC electric locomotives

Mass of a passenger train and, accordingly, number of cars in its composition is selected based on the amount of passenger traffic on the section, determined by the seasonal demand for transportation in each direction. In one direction of the section serviced by an electric locomotive, the mass of a passenger train may differ several times from the opposite direction, which depends on the destination station of the train and the period of its circulation. At present, in addition to 6-axle electric locomotives of the ChS2T and EP2K series, more powerful 8-axle electric locomotives of the ChS7 series operate in the same schedule for traction of passenger trains on railway sections electrified with direct current with a voltage of 3 kV catenary. All three series of the considered electric locomotives are designed for a maximum operating speed of up to 160 km/h. In this regard, there is a situation with the underutilization of the maximum speed and excess power of the ChS7 electric ocomotives, especially when operating with passenger trains of medium and low weight and a limited speed of 120 km/h. The comparative data on the specific power consumption of the EP2K 6-axle electric locomotives and the ChS7 8-axle electric locomotives operating in the same schedule, presented in the article, indicate the need to find additional reserves for saving the specific power consumption when servicing passenger trains of medium and low weight with ChS7 electric locomotives. The electric locomotive power system includes traction and auxiliary electric machines. The article discusses ways to turn off part of traction motors, which can be carried out with a standard electric locomotive circuit. However, when one section of the electric locomotive is turned off, the power of the four traction motors remaining in operation is not always sufficient to drive a passenger train according to the schedule. Therefore, a variant of improving the power circuit of an electric locomotive in the process of carrying out its overhaul is proposed. This option represents the modernization of the power circuit of the ChS7 electric locomotive when operating on a series-parallel connection with a pair of traction motors disconnected. As a result, the power circuit of the 8-axle electric locomotive operates similarly to the circuit of 6-axle DC electric locomotives with a collector traction drive. The expected savings in specific power consumption can reach 15% in comparison with the operation of an 8-axle electric locomotive ChS7 in normal mode. Switching off one section of the electric locomotive and further running the train on four traction electric motors will reduce the specific power consumption by up to 25%.