Online Detection and Location of Soft Faults in Wired-Power Networks Mostafa Rizk †‡§ , Hassan Semaan † , Hanine El Cheikh-Ibrahim † , Ziad Noun † , and Zouhair El Bazzal † † Lebanese International University (LIU) ‡ IMT Atlantique, CNRS Lab-STICC, UBL, F-29238 Brest, France § Lebanese University, Physics and Electronics Department, Hadat, Lebanon Abstract—The past decade has witnessed an insane exponential upraise in research and development in different technological systems. This was accompanied by advanced complex electrical employments striving for more and more electrical energy. Accordingly, extended and wider power networks for energy transmission and distribution became necessary to cover this increasing demand. Unfortunately, power networks are con- fronted by natural and human-made disorders leading to the appearance of faults. In this paper, an approach based on the tenets of the time reversal concept is proposed. This approach, referred to as the on-line time reversal (OTR), benefits from the time reversibility of wave equations to refocus the time-reversed back-propagated electromagnetic waves onto the location of the fault. The main advantage of the OTR is its ability to test live transmission line networks without the need to disconnect the whole network from its infrastructure. In order to verify the feasibility of the proposed method in detecting faults and to evaluate its accuracy in localization, simulation and experimental based setups have been conducted targeting single and branched transmission line networks. The obtained results verify that the use of OTR leads to accurate detection and location of faults in different wiring configurations. Index Terms—Fault location, soft faults, Online detection, wire networks, time reversal, DORT, OTR. I. I NTRODUCTION Nowadays, electrical cables exist widely in most systems where they are involved in transferring energy and/or informa- tion and consequently ensure their proper functioning and de- sired performance. The tremendous increase in electrical em- ployments in various fields leads to the up-growth of electrical cables deployment. Cable networks are now the cornerstone in most systems that are widely utilized to distribute power and communication signals. In addition, the length of the cables is increasing proportionally with the growing complexity of electrical systems. On the other hand, the wide use of electrical cables makes their reliable and safe operation crucial and vital for all interconnected systems since a single faulty wire can result in the failure of an entire system [1] [2]. In fact, wired connections are likely exposed to compelling natural or human-caused conditions (heating, humidity, pressure, snow, switching, etc.) leading to the appearance of unexpected dis- turbances along the transmission lines of a power grid. Such disturbances may lead to a total interruption of transmission as in the case of open or short circuits. Furthermore, in huge number of systems, a considerable number of electrical wires are embedded to perform safety and control operations. Hence, the performance degradation of wires due to the appearance of a major defect might have a significant negative influence on human lives and economy. For instance, wiring faults have been accounted as the major reason behind fires in human occupied and non-occupied facilities. In the United States of America only 1,298,000 fires were reported in 2014 which cause the death of 3,275 person, the injury of 15,775 civilians and property damages of 11.6 billion dollars. [3]. Particularly, the National Transportation Safety Board (NTSB) investigation revealed that it was the electrical wiring fault that caused the Boeing 747 TWA Flight 800 disaster in 1996 and the crash of a Swissair MD-11 in 1998 taking the lives of hundreds of passengers [4]. Electrical wires are subjected to harmful defects due to external effects such as chemical contamination, mechanical aggression, etc., or internal ones such as effects due to manufacturing defects, local heating, etc. Such defects lead to harmful modifications that are mainly categorized under hard and soft faults. Hard faults is the term referred to short and open circuits which lead to preventing the propagation of the signal along the wire; whereas, soft faults refer to the minor alterations namely insulation damage, cracks, frays, crushed lines, water infiltration, etc. Although soft faults are characterized by slightly modifying the properties of the cable without causing a significant impact on the whole system operation, they are considered dangerous because of the difficulty in detection. Soft faults can evolve eventually into hard faults [2]. Besides, the severity of soft faults should never be underestimated as they are at the origin of electrical arcing while the damaged cable is in use, thus threatening the safety of the system. Accordingly, the reliable and safe use of cables requires testing methods which are capable of detecting and locating the presence of soft faults. Hence, developing robust procedures for the detection of minor disturbances become essential need as an early alerting method in order to ensure the safe, reliable and proper functioning of a network. The importance of effective fault early-detection techniques lies in reducing the potential of putting in jeopardy a whole system. In addition, localizing the fault position facilitates maintenance operations and ensures the quality of service. Throughout the last few decades, different techniques have been proposed for testing the health of the wires and to detect and locate faults. In fact, techniques relying on the human  ,QWHUQDWLRQDO &RQIHUHQFH RQ &RPSXWHU DQG $SSOLFDWLRQV ,&&$   ,((( 