Wire Fault Research Articles

A Digital Signal-based Prognostic Approach to Factory Automation

A data network from a control system is usually consist of complex wiring systems to communicate with manufacturing lines. The electrical connections by the wiring systems can be deteriorated by wire faults such as chafing in the wiring system. During the life cycle of the wiring system, field stress conditions such as mechanical stress condition often cause and intensify the wire faults. The progress of wire fault can cause other wire failures such as cutoff or arcing. Furthermore, failures in the connected wires may eventually cause malfunctions in facilities of manufacturing lines. In order to prevent serious failures, health of the wiring system can be monitored in real time to repair or replace the damaged wires before the time to failure. However, the conventional approaches to wire health monitoring often require additional connections to the wiring system due to additional monitoring devices. Thus, the operation of the facilities may be interfered when the monitoring devices monitor wires. As a result, the conventional approaches, which require additional devices, have difficulty detecting the extent of wire damages in real time, and may end up neglecting the progress of chafing. In this study, a method for wire health monitoring is developed to prevent wire failures by monitoring wiredamages in real time. Digital signal is affected adversely by impedance discontinuity on the transmission line. By monitoring the integrity of digital signal continuously, time to failure can be predicted in real time depending on the extent of wire damage. In addition, an accelerated wire abrasion test was designed to damage wires gradually. During the abrasion test, the integrity of the transmitted digital signal was continuously deteriorated. The monitored signal makes it possible to extrapolate the degradation pattern of the signal parameters depending on the extent of wire damage. Thus, the results in this study validate that the proposed method is capable of monitoring the wire damage to diagnose a wiring system with real-time information.

Security Analysis and Preventive Measures of EWIS

In the field of airborne electrical equipment safety, the major concern has been focused on the reliability of the equipment, and the long-term neglect of the connection of each of the airborne electrical equipment cable failure. In order to reduce the probability of wire fault effectively, separate it from the airborne electrical equipment system for research. Firstly, starting from the basic problem of the security of EWIS (Electrical Wiring Interconnection System), the steps of the quantitative analysis of the EWIS fault are given. Secondly, based on the analysis of the failure mechanism of the aviation wire, the advantages and disadvantages of different detection techniques are compared. Finally, the scheme of improving EWIS fault detection ability for the new and old aircraft with different maintenance modes is presented.

An efficient numerical-based crosstalk avoidance codec design for NoCs

With technology scaling, crosstalk fault has become a serious problem in reliable data transfer through Network on Chip (NoC) channels. The effects of crosstalk fault depend on transition patterns appearing on the wires of NoC channels. Among these patterns, Triplet Opposite Direction (TOD) imposes the worst crosstalk effects. Crosstalk Avoidance Codes (CACs) are the overhead-efficient mechanisms to tackle TODs. The main problem of CACs is their high imposed overheads to NoC routers. To solve this problem, this paper proposes an overhead-efficient coding mechanism called Penultimate-Subtracted Fibonacci (PS-Fibo) to alleviate crosstalk faults in NoC wires. PS-Fibo coding mechanism benefits the novel numerical system that not only completely removes TODs but also, is applicable to a wide range of NoC channel widths. The PS-Fibo coding mechanism is evaluated using BookSim-2 and VHDL-based simulations in the terms of codec efficiency on the crosstalk fault reduction, codec power consumption, codec area occupation and network performance. Evaluation results, carried out for a wide range of NoC channel widths indicate that PS-Fibo can improve power consumption and area occupations of codec and NoC performance with respect to the other state-of-the-art coding mechanisms.

Chaos Time Domain Reflectometry for Online Defect Detection in Noisy Wired Networks

In many application domains, wire faults can have dramatic consequences. Live wire diagnosis is often required to ensure permanent monitoring of the health of embedded cables. A novel reflectometry-based method for online wire diagnosis is presented. Chaos time domain reflectometry (CTDR) takes benefit of the properties of chaotic signals and shows very good potential for the diagnosis of live wires (i.e., during their operational usage) and complex topology networks. In particular, CTDR shows high performances in very noisy environments: the detection and the location of hard defects are possible even in the case of negative signal to noise ratio and if several reflectometers inject their signals in the cable. This enables using CTDR for the distributed diagnosis of live complex topology networks of lengths up to several tens of meters. CTDR’s defect detection capacity is shown and experimentally verified: increasing the length of the probe signal lowers the noise level. A noise robustness analysis provides a means to choose the signals parameters necessary to ensure specified detection performances.

Wire Fault Diagnosis in the Frequency Domain by Impedance Spectroscopy

The typical methods for the wire fault location are the time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR). In TDR, attenuation and dispersion of the reflected signal limit the reachable accuracy for wire faults location. Because time of flight is evaluated, the wire faults with small impedance changes are difficult to locate. The FDR method has better accuracy than the TDR method, because power signals are used as incident signals and Fourier transform is applied to locate wire faults. However, it is difficult to identify the types of wire faults. A new technique is proposed to detect and locate the wire fault using impedance spectroscopy (IS). IS is applied to measure the input impedance of the wiring system. The load impedance of the wire fault can be abstracted from the input impedance in order to identify the type of wire faults. The input impedance is a period function of the frequency and the period of this function is linearly proportional to the distance to the fault. The fast Fourier transform of the input impedance can give a single spike to locate the wire fault. This novel method enables the location of hard (open and short circuits) and soft (wire faults with small impedance changes) faults. The input impedance of the wire faults in the defined low-frequency range can be applied to identify the types of wire faults. The capacitance and inductance of the cable system can be applied to detect the wire fault if it is open or short circuit. The measurement deviation of the wire fault location in this paper is maximal 40 cm and is independent of the distance to wire faults.

Ignition Characteristics of Residential Series Arc Faults in 220-V HIV Wires

Unintentional arc faults due to damaged power line cords and loose connections can cause serious fires; thus, they are a safety hazard in residential areas. Therefore, arc fault circuit interrupters are being increasingly used in homes to protect against arcs that may cause fires. In this paper, we analyzed the ignition characteristics of series arcs on the basis of load current. Furthermore, we recommended suitable arc clearing times through characteristics analysis in the Korean residential electric environment. We determined the arc clearing time via the carbonized path arc clearing time test using an ultraviolet signal detecting system according to the test method of the UL 1699 standard. In the experiments, heat-resistant indoor PVC insulated (HIV) wires, which is a type of residential electrical wire, were used as the wire specimens.

Physics-Based Precursor Wiring Diagnostics for Shielded-Twisted-Pair Cable

The capability to locate and characterize precursor wiring faults, such as chafing or pinching potentially enables preventive maintenance well before hard failures occur, thus maximizing system functionality and safety while minimizing out-of-service time. Toward this goal, results are presented on the application of a deterministic Bayesian inference procedure well suited for detecting chafing and pinch faults through the use of a newly developed physics-based model for shielded-twisted-pair cable. This method is significantly faster than more traditional nondeterministic Bayesian methods, such as Markov chain Monte Carlo, and retains many of the desirable features inherent to the Bayesian approach. These include the ability to quantify estimation uncertainty and model evidence in probabilistic terms, which then enables the study and design of noise-tolerant fault detection algorithms capable of classifying different types of faults. The fault parameter estimation results from both laboratory and field measurements on a C17 jet engine are shown to demonstrate the achievable model fidelity and the overall viability of the approach.

A Probabilistic Spatial Distribution Model for Wire Faults in Parallel Network-on-Chip Links

High-performance chip multiprocessors contain numerous parallel-processing cores where a fabric devised as a network-on-chip (NoC) efficiently handles their escalating intertile communication demands. Unfortunately, prolonged operational stresses cause accelerated physically induced wearout leading to permanent metal wire faults in links. Where only a subset of wires may malfunction, enduring healthy wires are leveraged to sustain connectivity when a partially faulty link recovery mechanism is utilized, where its data recovery latency overhead is proportional to the number of consecutive faulty wires. With NoC link failure models being ultimately important, albeit being absent from existing literature, the construction of a mathematical model towards the understanding of the distribution of wire faults in parallel on-chip links is very critical. This paper steps in such a direction, where the objective is to find the probability of having a “fault segment” consisting of a certain number of consecutive “faulty” wires in a parallel NoC link. First, it is shown how the given problem can be reduced to an equivalent combinatorial problem through partitions and necklaces. Then the proposed algorithm counts certain classes of necklaces by making a separation between periodic and aperiodic cases. Finally, the resulting analytical model is tested successfully against a far more costly brute-force algorithm.

CHAOS TIME-DOMAIN REFLECTOMETRY FOR FAULT LOCATION ON LIVE WIRES

We propose a chaos time-domain reflectometry (CTDR) for locating faults on live wires. This method uses a chaotic output of an improved Colpitts oscillator as probe signal, and detects wire faults by correlating a duplicate with the echo of the probe signal. Benefiting from the anti-jamming of the correlation function of the wideband chaos, fault location on live wires can be achieved. We experimentally demonstrate the detection for live wires in a digital communication system, in which a type of digital signal named high density bipolar of order 3 (HDB3) is transmitted. The effects of the chaotic probe signal on the bit error rate (BER) of the transmitted HDB3 at different rates are analyzed. Meanwhile, the influences of the backward HDB3 reflected by wiring faults on the signal-noise-ratio (SNR) of CTDR measurement are examined experimentally. The results show that fault detection on live wires is achieved when the power of the chaotic probe signal is about from -24.8 dB to -13.5 dB lower than that of the transmitted digital signal. In this case, the BER is kept less than 3E-10, and the SNR of CTDR is higher than 3 dB. Besides, the auto-correlation properties of the improved Colpitts oscillator at different states are investigated experimentally to explore the suitable chaotic states for the CTDR.

Diagnosis of Multiple Wiring Faults Using Time-Domain Reflectometry and Teaching–Learning-Based Optimization

Time-domain reflectometry has proven to be one of the best methods for wiring network diagnosis, and it can easily be applied to the detection and localization of defects, while only requiring one access point to the wiring network. In this article, a novel approach combining the time-domain reflectometry response extracted from vector network analyzer measurements and the teaching–learning-based optimization technique is developed and applied to the diagnosis of wiring networks. The proposed approach consists of two steps. In the first step, propagation along the cables is modeled using the forward model. In the second step, teaching–learning-based optimization is used to solve the inverse problem to deduce physical information about the defects in the wiring network. The proposed approach has been successfully tested on several cases and for different configurations. Comparisons of the proposed time-domain reflectometry/teaching–learning-based optimization approach results with measurements reveal that this approach has a high potential and is very effective for wiring network diagnosis.

Surface dislocation nucleation controlled deformation of Au nanowires

We investigate deformation in high quality Au nanowires under both tension and bending using in-situ transmission electron microscopy. Defect evolution is investigated during: (1) tensile deformation of 〈110〉 oriented, initially defect-free, single crystal nanowires with cross-sectional widths between 30 and 300 nm, (2) bending deformation of the same wires, and (3) tensile deformation of wires containing coherent twin boundaries along their lengths. We observe the formation of twins and stacking faults in the single crystal wires under tension, and storage of full dislocations after bending of single crystal wires and after tension of twinned wires. The stress state dependence of the deformation morphology and the formation of stacking faults and twins are not features of bulk Au, where deformation is controlled by dislocation interactions. Instead, we attribute the deformation morphologies to the surface nucleation of either leading or trailing partial dislocations, depending on the Schmid factors, which move through and exit the wires producing stacking faults or full dislocation slip. The presence of obstacles such as neutral planes or twin boundaries hinder the egress of the freshly nucleated dislocations and allow trailing and leading partial dislocations to combine and to be stored as full dislocations in the wires. We infer that the twins and stacking faults often observed in nanoscale Au specimens are not a direct size effect but the result of a size and obstacle dependent transition from dislocation interaction controlled to dislocation nucleation controlled deformation.

The Electrical Standard Practices in the Role of Airbus Aircraft Maintenance

wiring fault is a fault in the fault plane, along with the development of the aviation industry, increasing aging aircraft, how to use the manual fault and failure analysis, mature locomotive repair personnel each should master the basic skills of Boeing aircraft repair. combined with a specific fault, in conjunction with the relevant manuals, carries on the analysis to the wire and remove the fault.

Design and Implementation of Wireless Live Wire Fault Detector and Protection in Remote Areas

remote and hilly areas, the faults in the live wires are difficult to analyse. The faults in the wire may be due to breakage in the wire, breakage due to heavy rain, snowfall and land slide, human and animal contact or lightening strike. In an electric power system fault is any abnormal electric current. RF Transreceivers have been proposed for detection of faults in the live wire. This technique can detect the faults in the wires, unapproachable by humans. RF Transmitter units are fixed along the length of wire at regular intervals, the RF receiver unit is placed at approachable area. Signal communication occurs between the transmitter and receiver unit. The transmitter units designed consists of a RF transmitter module which transmits the signal as long as it receives the power. The microcontroller receives the signal through the relay. The voltage fluctuation circuit constantly monitors the voltage level in the wire,and auto cuts-off power in case of voltage fluctuations. The transmitter unit which doesnot transmit the signal, indicates the area of fault in the wire. The receiver unit comprising of the RF receiver module,receives all the signals from the transmitter units accordingly. If all the transmitters' signals are received,this indicates that there is no fault in the wire. The transmitter unit from which the signal is not received,indicates the portion or area of the fault in the wire. The relay circuit in the transmitter unit auto cuts-off power in case of the fault detected. The decoder circuit connected to the RF receiver passes the signal to the microcontroller which is displayed. These messages can be transferred to any desired location through the GSM module present on the receiver unit. Hence the fault location can be detected and the circuit is protected in case of fault and voltage fluctuations in the wire. KeywordsLCD,GSM, TDR.

The Standard Wiring Practices in the Role of Boeing Aircraft Maintenance

wiring fault is a fault in the fault plane, along with the development of the aviation industry, increasing aging aircraft, how to use the manual fault and failure analysis, mature locomotive repair personnel each should master the basic skills of Boeing aircraft repair. combined with a specific fault, in conjunction with the relevant manuals, carries on the analysis to the wire and remove the fault.

Model-based identification of wire network topology

A new technique is proposed to locate wire faults and identify wire network topology using Impedance Spectroscopy (IS). The propagation along the cables is analytically modelled with flexible multi section cascading features utilizing frequency dependent scattering parameters. Therefore, it does not have the common numerical method problems. The transmission line model has the same spectrum as the measured reflection coefficient (ρ) of wire under test (WUT) so that same practical effects such as skin and proximity effects, signal loss, dispersion and frequency dependent signal propagation can be exactly incorporated. For determination of model parameters an inverse problem should be resolved and differential evolution (DE) approach is proposed. The novel method allows locating hard (short and open circuit) and soft (frays and junctions) faults and also for characterization of defects in the branches of network. Results are presented to validate and illustrate the performance of this proposed method.

Analysis of the commutation failure of inverters during open-conductor faults at the AC side

Summary Commutation failures (CFs) in inverter stations disturb the power system greatly. Open-conductor fault (OCF) is a longitudinal fault. When it occurs in the alternating current (AC) system, the three-phase voltages are unbalanced. Under this circumstance, it is generally considered that inverters can maintain normal commutation order for the voltage support provided by other transmission lines in normal operation. In this paper, the possibility of the inverter CF during OCF is established. The sensitivities of the CF to the AC voltage disturbances caused by the changes of the AC superposition voltage are analyzed. It is concluded that the sensitivities of the CF with different transformer wiring schemes and fault types are diverse. Before the CF happens in the inverter station during OCF, the CF may occur in other inverter stations of the multi-terminal direct current systems with the constant current and constant extinction angle control strategies. Simulation studies are performed in the PSCAD/EMTDC software (Copyright(C)2006, Manitoba HVDC Research Centre, Canada), and the theoretical analysis is validated by the simulation results. Copyright © 2014 John Wiley & Sons, Ltd.

A New Algorithm for Wire Fault Location Using Time-Domain Reflectometry

In time domain reflectometry (TDR) attenuation and dispersion of the reflected signal limit the reachable accuracy for wire faults location. Because time of flight is evaluated, the wire faults with small impedance changing are difficult to locate. In this paper, a novel method for the TDR-based wire fault detection is presented by transfer function analysis in the time domain. For the determination of the transfer function, a deconvolution should be carried out. Thereby, an inverse problem is to be solved by an adaptive filter approach. Adaptive filters are able to reduce spurious noise of the deconvolution and lead to an acceptable deconvolution estimate. Therefore, a high signal-to-noise-ratio can be reached. The filter's stopband characteristics are optimized by optimization technique to reduce the noise components of the transfer function in the frequency domain. For that a nonlinear fitting procedure is proposed using the Riad-Parruck optimization criterion. The developed method can locate both hard faults (open and short circuits) and soft faults with small impedance changes, and identify the type of wire faults simultaneously in a controlled laboratory environment (without the impedance changes from mechanical vibration, movement, and moisture). The algorithm using adaptive filters and optimization techniques is proposed in this paper for the traditional TDR method, but it is general for most other reflectometry approaches. The estimated wirings are coaxial cables and twisted pair cables, which are used in electrical and power distribution systems.

Location of Wire Faults Using Chaotic Signal Generated by an Improved Colpitts Oscillator

We propose a method to locate wire faults using a chaotic signal generated by an improved Colpitts oscillator. The chaotic signal is divided into two parts: one serves as a reference signal, and the other serves as a probe signal which is sent down to the wire. The fault is detected by correlating the reference signal with the probe signal back-reflected from the fault. Experimental and numerical studies show that the chaotic signal generated by the improved Colpitts oscillator has a broad spectrum and excellent correlation properties. Using this chaotic signal, we experimentally prove our method can be used to locate open circuits, short circuits, impedance discontinuities and other different damage cases on wires, and also demonstrate its ability for testing live wires through the numerical simulation. The results show that a spatial resolution of 0.2 m and a maximum range of about 930 m can be achieved. Furthermore, the interference margin is about 167 dB for the digital signals such as Mil-Std 1553 data on wire.

Range Finding and Fault Locating with Chaotic Signal

In this paper, we review our recent works on range finding and fault locating in optical network and wire with chaotic signal. Using a distributed-feedback semiconductor laser with optical feedback as chaotic source, we developed a prototype chaotic optical time domain reflectometer which can achieve a range- independent resolution of 4cm and measurable distance of about 70km. We further present the measurement of faults in the wavelength-division-multiplexing passive optical network (WDM-PON) by using a wavelength-tunable chaotic laser. Moreover, we also demonstrate the location of wire faults or impedance discontinuities with chaotic signal. Our results show that the fault location using wideband chaotic signal is a promising method of precise diagnoses for WDM-PON and electric cables.

Ambiguity Cancellation for Wire Fault Location based on Cable Life Profile

Although reflectometry is an efficient method to diagnose simple topologies (such as transmission line, Y shape network), it remains limited in the case of complex branched networks due to multipath fading of the test signal during its propagation. Generally, the knowledge of the environment in which the cable operates gives an additional idea about the fault location. The current paper proposes to introduce the cable life profile (such as environmental stress, type, age, noise, etc.) to detect and cancel diagnosis ambiguities and provide a precise location of the fault. Bayesian Network (BN) seems to be a suitable solution to offer a coherent representation of knowledge domain (reflectometry method, cable characteristics and network heterogeneity) under uncertainties (fault(s) location, systems reliability and measurement precision). In this work, a two-stages BN model for diagnosis using reflectometry in branched networks is proposed and simulation results are discussed.