The paper presents a new generalized matrix method for modeling any kind of shunt and series faults as single or simultaneous faults in arbitrary combination. The basic idea of this method consists of the formulation of the fault boundary conditions by 3/spl times/3 matrices, the so-called fault matrices. The fault matrices for the original quantities are incidence matrices. For using the matrix method in any modal components, the fault matrices are only to transform into the modal components respectively. The proposed approach can be used for fault studies under steady-state conditions based on the nodal admittance approach, as well as under transient conditions by means of the EMTP/ATP algorithm.