The Power System Simulator is a state of the art graphical program for the PC- Windows(tm) environment (XP) that emulates the operation of a power system modeled by the user, under the conditions and maneuvers that the user dictates. Main product functions are power flow, short circuit, stability for transient state modeling, protection coordination, system optimization features and additional applications. With the basic tools, the simulator has an ample range of options for developing a planning study of the power system and analyze its behavior in stationary conditions. The purpose of this program is not only to simulate the behavior of a power system but to help the user in calibrating and coordinating of the protection equipment relays, by means of system and relay behavior visualization. There is also an ample library of relay operation curves. If the user requires simulating the operative behavior in transitory and dynamic conditions, This software module shows faults and stability options that can be simulated in the same graphical environment as the other options. Although it is a power system simulator and therefore it is focused on looped networks, its flexibility makes it equally competent for radial system analysis. Thus, it includes applications for radial networks optimization such as optimal reconfiguration (under the criteria of losses minimizing or reliability maximizing), and optimal location of new substations.