This paper focuses on identification of vulnerable lines and nodes of the power grid (PG) network whose removal disrupt on its operational capability. Here the topological parameters are derived from CN theory, and these are used to identify the most important elements i.e., lines and nodes of the PGs. Based on this concept, the number of attack strategies are illustrated and also applied to different IEEE bus networks, e.g., IEEE 39 and 300 buses. We show that in case of electrical PG network, weights are related to electric concepts, and that can enhance the representation of the PG. This work identifies the vulnerable lines and nodes of both weighted and unweighted networks, and quantify the results by applying the concept to real AC power flow model. We conclude that a weighted network analysis can give a better vulnerability assessment than that of an unweighted network.