A coordination study, determines the settings of OCPDs in an electrical power system. Ideally speaking, the selection of settings will both protect the electrical equipment as well as removes a smallest portion of electrical system from service in order to isolate a fault. In most cases, some compromises are unavoidable because of the safety of operating personnel. To determine a most suitable setting for an Overcurrent protective device, Time current curves are plotted either by manually or by using software. Interpretation of TCCs is done by an experience PSS engineer to qualify if the study achieves required goals.