摘要:Electrical Network as one of the main lifeline plays vital role in the economic, social and political relations of a country.Among the various components of Electrical Network, such as power plants, substations and transmission lines, high voltage substations have important consideration, and Play a vital role in network. So if for any reason disorder happens on the transmission and distribution of the network happens, it may cause irreparable damage. So this study is going through the evaluation of the seismic power substation as an important part of Electrical Network. assess the vulnerability and seismic behavior of power substation is to use the fragility curves. In this method, the evaluatof the value of seismic vulnerability of structures proportion with the seismic parameters will be expressed. In fact, the aim of fragility curves is to create a relation between a failure criterion and a criterion of magnitude. In this study the circuit breaker as one of the most widely used equipment in power substation will be study and fragility curves will be drawn for it.