A novel correlation tester for multicore power cable fault finding and identification using pseudonoise sequences

A novel pulse tester correlation strategy, using pseudonoise (pN) sequences, is presented as an alternative to Time Domain Reflectometry (TDR) for multicore power cable fault location and identification. The fulcrum of this method is the cross correlation (CCR) of the fault response echo with the input pN test excitation which results in the extraction of 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 injection. This fault identification procure can used in a number of essential industrial scenarios embracing overhead power lines and underground cables in inaccessible locations which rely on a pathway for power transfer and/or signal propagation. A key feature is the potential usage of Pseudorandom Binary Sequences (PRBS) for long distance fault finding over several cycles at low amplitude levels online to reject normal sinusoidal power flow, signal traffic and extraneous noise pickup for the purpose of multiple fault coverage, resolution and identification. In this paper the PRBS method of cable fault diagnosis is presented, along with a single phase transmission line model, for fault distance measurement. Key experimental test results are presented for pN fault finding using a four core steel wired armoured (SWA) copper power cable with different types of faults encountered in practice, under laboratory controlled conditions, for proof of concept. The measured CCR fault response demonstrate the effectiveness of the PRBS test method as a tool in fault type identification and location. The results obtained substantiate 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 and comparison with known fault resistance terminations, known apriori, and link distances in power line experimental testing.