A novel fault finding and identification strategy using pseudorandom binary sequences for multicore power cable troubleshooting

Abstract

A novel fault finding correlation methodology, using pseudorandom binary sequences (PRBS), is presented as an alternative to Time Domain Reflectometry (TDR) for multi-core power cable fault location and identification. The fulcrum of this method is the cross correlation (CCR) of the fault echo response with the input pseudonoise (pN) test sequence which results in a unique signature for identification of the fault type, if any, or load termination present as well as its distance from the point of test stimulus insertion. This troubleshooting procedure can used in a number of key industrial scenarios embracing overhead power lines and underground cables in inaccessible locations. A key feature is the potential usage of pseudonoise sequences for long distance fault funding over several cycles at low amplitude levels online to reject normal mains voltage, communications signal traffic and extraneous noise pickup for the purpose of multiple fault coverage, resolution and identification. In this paper a single phase transmission line model is presented with PRBS stimulus injection under known load terminations to mimic fault conditions encountered in practice for proof of concept. Simulation results, for known resistive fault terminations, with measured CCR response demonstrate the effectiveness of the PRBS test method in fault type identification and location. Key experimental test results are also presented for pN fault finding using a four core SWA copper power cable, under laboratory controlled conditions, which substantiates the accuracy of PRBS diagnostic CCR method of fault recognition and location using a range of resistive fault terminations. The accuracy of the method is further validated through theoretical calculation via estimated fault reflection coefficients, voltage standing wave ratios and comparison with known fault resistance terminations, known apriori, and link distances in power line experimental testing.