New approach for the fault diagnosis of linear analog networks

This paper presents two new theories for the fault diagnosis of the linear analog networks of unknown impedance matrices but of known terminal (port) voltages. The concept of the companion network is proposed to fault diagnose the network under test. The impedance matrices of the nominal network and its companion network constitute two overdetermined systems of equations with the two corresponding network port voltage vectors. The idea is based on the block dependency between the nominal impedance matrix of the network under test and the impedance matrix of its companion network after excluding the circuit element or subnetwork under test. If the companion impedance matrix is consistent with the measured port voltage vector, then, the nominal impedance matrix corresponding to the circuit element or subnetwork under test must also be consistent with the same measured port voltage vector which means that this circuit element is faulty or is one of the entities of the ambiguity fault set. By this way all circuit elements can be tested using the companion network only.