A new approach to improve the reconfiguration operations of distribution systems is presented in two papers. In this first part an economic dispatch (ED) through radialization method for medium voltage (MV) distribution networks with several alternative supply points and several energy prices is presented. The optimization criterion is based on energy purchase cost minimization to supply both the load and the loss. The ED through radialization (EDR) method assesses the economic impact of different energy prices for alternative supply points on the operative radial topology for a specific load level. Capacity limits of supply points and MV lines are considered, as well as the quality technical product using ac power flow calculations. The results obtained for a distribution network widely used in the literature show the effectiveness of the proposed methodology. The second part presents a methodology to determine the optimal reconfiguration plan for short and medium terms. This approach integrates purchase and switching costs associated to the reconfiguration plan.