While most researches in developed countries are based on power congestion and transmission lines of more capacities, electric power supply companies in most developing countries still have limited electric power generating plants. Limited resources such as: water, oil, gas, coal, nuclear, etc., are the causes of power ration in these countries. In this paper, operating costs of a thermal plant operating at rationing base is analyzed. Using optimal active power dispatch algorithm, the effect of power reschedule at different location on generation costs is obtained and analyzed. Fuel cost and transmission losses are considered. It is observed that, at some location, rationing affect the electric company economy due to the high loss and load under rationing, time of rationing and the uneconomical generating cost. This research contribution is to assist in economical projection for the electric companies and decide the location and time of the rationing. Results presented are based on IEEE 14-bus testing system, IEEE 30-bus testing power system.