Single shunt fault diagnosis in ladder structures with a new series of numbers

Diagnosis of a single shunt fault in a ladder structure, by means of conventional input/output ports only and by making measurements at a single test frequency, is presented. Three sets of measurements, namely, forward attenuation, backward attenuation and a specific backward attenuation with an additional series arm impedance, with their corresponding phase-shifts for a sinusoidal input of a particular frequency, are found sufficient to diagnose a fault. The attenuations are expressed in terms of a set of polynomials defined by Morgan-Voyce (1959). The sum of forward and backward attenuation, as well as the difference between forward and the specific backward attenuation, in association with their corresponding phaseshifts, allow the authors to locate and identify faults. A proposition has been made to remove the ambiguities encountered in fault isolation towards the middle of the ladder structure