In recent years, Phasor measurement unit (PMU) is found to be one of the most promising technology in the field of monitoring and controlling of electrical grids. PMUs are to be used to achieve accurate measurements of current and voltage phasors at synchronized time stamp through global positioning system. The high installation costs associated with PMU have restricted its use and increased the requirement for optimum allocation of PMUs. This paper proposes a methodology to solve the optimal PMU placement (OPP) problem in order to obtain a completely observable network by using Binary Dragonfly Algorithm (BDA). A number of simulations are carried out on various standard IEEE bus test systems to ensure the reliability and feasibility of the algorithm. The results obtained are compared between the proposed method and other algorithm. The comparison demonstrates the potential of the proposed algorithm with lower CPU time and better convergence. The OPP also conforms the reduction in transmission losses.