A Novel Method Based on Spread-Spectrum Time-Domain Reflectometry for Improving the Distance of Cable Fault Detection

Spread-spectrum time-domain reflectometry (SSTDR) is used to detect cable faults online. In this study, the signal model of SSTDR cable fault detection was established, and two factors, namely, the incident leakage signal and the impedance mismatch between the device and the cable, that affect fault detection performance were analyzed. In this study, an improved method of SSTDR cable fault detection was proposed by combining the transmitter–receiver isolation and trapper. Calibration was performed to obtain the optimal parameters of the circuit. The proposed method can reduce the signal energy leakage from the transmitter to the receiver circuit and suppress the impedance mismatch between the device and the cable. The parameter calibration process of transmitter–receiver isolation and trapper, and the influence of various parameters on the performance of cable fault detection were detailed experimentally. The experiments revealed that the improved SSTDR fault detection can detect faults at various distances. At frequencies of 20, 10, and 5 MHz, the fault detection distance reached 68, 110, and 210 m, respectively. Test results revealed the effectiveness of the proposed method.