Although most MV 10(20) kV distribution networks (DM) are in operation with a radial structure, in most networks there are additional elements that form loops and are kept disconnected for the same reason. This means that, in principle, for real DMs there are several ways of supplying TS 10(20)/0.4 kV, that is, several alternative network topologies. The problem of optimal DM reconfiguration refers precisely to finding the optimal topology that best fulfills the set objective function. The objective functions that are usually considered in the mentioned problem are mainly related to the minimization of the total losses in the DM, the equalization of the voltage profiles along the MV leads, the equalization of the load on the leads or a combination of the mentioned criteria. In doing so, care is taken to maintain the radial structure of the network’s power supply and to satisfy various physical and operational constraints in the network. Considering the number of possible topologies, in most real ring-line distribution networks it is simply not possible to examine the entire solution space and choose the optimal topology. In this paper, a mathematical formulation is given for solving the problem of determining the optimal DM topology based on mixed integer programming with the approximation of the constraint by a second-order cone. The possibility of applying the described mathematical model and the improvement of the operating conditions achieved by its application is shown on the real distribution network of HEP-ODS.