Non-intrusive Cable Fault Diagnosis Based on Inductive Directional Coupling

This paper develops and applies an inductive directional coupling technology based on spread spectrum time domain reflectometry for non-intrusive power cable fault diagnosis. Different from existing capacitive coupling approaches with large signal attenuation, an inductive coupling approach with a capacitive trapper is proposed to reduce signal attenuation, restrict transmitting the detection signal to power source, and eliminate the effect of the power source impedance mismatch. Moreover, a novel structure with two parallel couplers is developed to enhance the effect of capacitive trapper with small capacitance. The development, design, analysis, and implementation of the proposed approach are discussed in details. A series of simulations and experiments on cables with different fault modes at different locations are conducted, along with comparison with existing capacitive coupling approaches, to verify and demonstrate the effectiveness of the proposed method.