Diagnosis of Incipient Electrical Defects on Long Cables Using a Chaotic Duffing Oscillator

Electrical wires are always present in critical modern systems, for the transmission of energy and signals. Due to aging or harsh environmental conditions, cables can develop defects that can reduce their performance and create severe problems. Reflectometry-based methods have been studied and implemented over the last 30 years and have shown good performance in detecting faults in cable networks. They rely on the analysis of echoes created by faults on the cable, and can detect defects whose echoes are a few percent of the input signal. But these methods are limited when it comes to detecting incipient faults characterized by echoes one order of magnitude smaller. This article presents the proof of concept of an entirely different diagnosis method. The method proposed here does not analyze the signal returned by the cable but uses this signal to disturb a system in an unstable equilibrium position. A chaotic Duffing oscillator is coupled to the cable under test and a test signal is sent into the cable: the returned signal is added to the oscillator control signal. The system parameters are chosen so that the oscillator is at the limit of stability, and a very slight disturbance of the cable causes a change in behavior that is much easier to detect than a very small peak sometimes drowned in noise on a reflectogram. The sensitivity of this new method is higher than that of state-of-the-art ones, enabling it to detect faults of signature of 1% or less of the amplitude of the test signal in long cables.