The problem of ameliorating the voltage and mitigating power loss in electrical networks is a task that ought to be solved optimally. In this paper a novel way for locating FACTS devices optimally in a multi machine power system employing Partial Swarm Optimization and Genetic Algorithm (GA) is presented. By assessing the proposed method, the location of FACTS controllers, different type and rated values can be optimized simultaneously. Also, the proposed approach goals to evaluate the number of devices and their ratings in optimal way with the help of the optimization technique with the thermal and voltage limits taken into consideration. Various conditions of loading in the power system are taken into account during this method. The exploration of the proposed approach is accomplished on the IEEE 40-bus system.