Abstract In this paper will be determined the power losses for the steady-state condition of the system and for the whole day, the buses voltages, the active power supplied by the generators and the active power used by the loads for a test system for a whole day, considering the loads profiles. The test system comprises three generators and two loads. The buses voltages, active power supplied by the generators, active power used by the loads and the power losses will be determined with the Neplan software, using the Newton-Raphson extended method. The loads daily power demand will be defined using the Neplan facilities.