Analyses of Subsequent Faults

Renewed interest in resonant neutral grounding makes it important to have available methods for predicting accurately voltages and currents under abnormal system conditions. In this paper are discussed solutions of subsequent faults on power systems, often called simultaneous faults; included are systems so grounded that a single line-to-ground fault is not a short circuit. Based on a general selection of line locations to be faulted, analyses are made by component methods and 3-phase methods. Each analysis treats representation of the system, unbalance, and measurements. It is concluded that the component methods are more applicable to large systems, while small systems are more satisfactorily studied by the 3-phase methods. Advantages and shortcomings of the various solutions are indicated.