Electric Shock Hazards Research Articles

Implementation of Fast Fourier Transform and Artificial Neural Network in Series Arc Fault Identification and Protection System on DC Bus Microgrid

A microgrid is a cluster of electrical sources and loads that are interconnected and synchronized. Microgrid operation is typically divided into two modes, isolated or connected to the grid with a single or standalone control system. In this context, it can enhance the reliability and quality of electricity supply for connected customers. When using a microgrid system, it is important to consider the risk of series arc faults. Series arc faults are sudden bursts of flames resulting from ionization of gas between two electrode gaps. These faults can occur due to manufacturing defects, installation Errors, aging, or corrosion on conductor rods, leading to imperfect connections. Detecting series arc faults in DC microgrid system operations can be challenging using standard protective devices. Failure in the protection system can pose risks of fire, electrical shock hazards, and power loss in the DC microgrid.Therefore, a device has been designed to detect series arc faults by utilizing the fast Fourier transform method and artificial neural network, which function to analyze DC signal and make decisions when faults occur by examining the average sum of current frequency values during normal and fault conditions. In this study, the average sum of current frequency values during normal conditions was found to range from 0.35437 to 0.36906 A, while during fault conditions, it ranged from 0.21450 to 0.22793 A, with an average protection identification time of 1087 ms and an ANN output accuracy of 99.98%.

Design and Validation of Plate Earthing System for Equipment Earthing

Earthing system is an essential part of electrical installation as it helps in eliminating electrical shock hazards and also provide zero voltage reference point for the equipment. Design of an earthing system involves, measurement of soil resistivity of the proposed site for the electrode system installation & determining the conductor type & required number of earth electrodes in order to achieve earth resistance value. This paper describes the methodology followed in design and validation of a plate electrode earthing system for the equipment earthing in a new test laboratory, which had an earth resistance requirement of less than 1 Ohm as mandated by the equipment supplier. This will be helpful for personnel involved in the design of earthing system.

Instant EOFF measurement error in cathodically protected pipelines: A parametric assessment study

Buried pipeline systems benefit from mitigation wires (earthing systems) in order to be protected against electric shock hazards. Moreover, cathodic protection (CP) systems are incorporated into pipeline systems to provide protection against corrosion by injecting an impressed DC current. DC decoupling devices are normally installed between the pipeline's metallic wall and the earthing wire, functioning as a filter that blocks the DC component (of the CP system) while allowing the hazardous AC interference current to be dissipated into the earth. However, the internal capacitance of the DC decoupling devices introduces an error in the routine survey measurement of the CP effectiveness, as frequently reported by pipelines’ system operators. In this paper, the factors influencing this measurement error are investigated by modeling the electrical behavior of the CP-pipeline system. This investigation concluded that the capacitive discharge time constant and by extension, the measurement error highly depends on the pipeline resistance to remote earth (coating resistance), as well as on the number and the capacitance C of the capacitive DC decoupling devices. To this extent, methods for minimizing Eoff measurement error are proposed.

Penyuluhan Pencegahan Bahaya Listrik dan Petir pada Instalasi Listrik Rumah Tangga di Lembang Dewata Kecamatan Mappak Kabupaten Tana Toraja

Tana Toraja Regency as one of the national tourist destinations within the administrative area of South Sulawesi Province. Tana Toraja Regency, which has a city in Makale, is located at 3°06'17"S South Latitude and 119°51'07" East Longitude. Tana Toraja Regency has an area of 2,054.30 km² and has a population of 270,489 people. Tana Toraja Regency consists of 19 sub-districts, one of which was chosen to be the location of community service for the Electrical Engineering Study Program, namely: Mappak Lembang Dewata District. The distance between the capital of Tana Toraja Regency and the provincial capital of South Sulawesi reaches 314 km. Electrical installations should be designed and installed on the basis of as required in the PUIL. In addition, the requirements for technical personnel who will install an electrical installation must be certified for competence in accordance with Law No.30 of 2009 concerning electricity. However, there are still often news of accidents caused by electric shocks, both those who died and those who were only limited to electric shocks. Such is the case with the danger of lightning that constantly lurks in other living things. This lightning has the potential to cause lifelong disability until death. For this reason, we from the Abmas Team of the Electrical Engineering Study Program, Faculty of Engineering, UAJ Makassar, are here to bridge between ordinary people about the potential dangers of electricity and lightning strikes and preventive efforts that can be done so that they can be avoided from the possibility of avoiding these accidents. The abmas team from the UAJM Electrical Engineering Study Program will help the community to explain how to overcome this which has become an obligation to carry out the duties of the Tri Darma of Higher Education, one of which is Community Service. The real form of community service that will be carried out is to provide counseling to the lembang dewata community about; How should efforts be made to avoid and prevent the occurrence of electrical accidents and lightning strikes that will be conveyed to the general public. This counseling explains the sources of electric shock hazards in a household installation and how to prevent them, along with the potential dangers of lightning strikes and how to avoid them. The material is delivered in the form of visualization of imaginative and communicative models and drawings

Специфика заземления электрооборудования участка шахты в контексте соответствия критерию эффективности защиты персонала от электропоражения

The paper provides evidence that the existing standardized design concept of power supply systems for the mine sites inherently involves existence of an electrical shock hazard to humans when touching the phase of the network. This hazard is caused by the active and capacitive conductance of the insulation due to grounding of the central cores of the flexible shielded mining cables. The functional inefficiency of the ground fault protection used in the mining industry has been proved, including the cases of mine electric networks with high power consumption. An alternative concept was justified to design the power supply system for a mine section electric network, which excludes grounding of the central cores of the flexible cables. This approach implements the principle of selective shutoff protection of the electrical consumers in the mine section using local means to control the condition of insulation in the power connections.

Statistical Assessment of Electric Shock Hazard in MV Electrical Power Substations Supplied from Networks with Non-Effectively Earthed Neutral Point

This paper focuses on the evaluation of the electric shock hazard accompanying earth faults in a non-effectively earthed medium-voltage (MV) electrical power network. This hazard depends on the duration and value of the fault current. While the fault current depends on several factors, the most important is the neutral point earthing method. The value of the fault current affects the earthing-electrode voltage value, being the basis for the assessment of electric shock hazard in MV/LV substations. The earthing-electrode voltage is also influenced by the resistance of the substation earthing, which in practice is random. Therefore, an original statistical evaluation method for assessing the electric shock hazard has been developed and presented in this paper. It is based on a statistical model of the MV/LV substation earthing resistance, worked out on the basis of experiments and measurements in real electrical power networks. This method can be used for the determination of statistical distributions of earthing-conductor voltages in real electrical power networks, and on this basis, the MV/LV substations with rates of electric shock hazard that are too high can be indicated. This also makes it possible to determine the longest permissible fault current interruption times or the highest permissible earthing resistances for specific substations. This method is also applicable when selecting the neutral point earthing method. The developed method was used in all of the above proposed areas by performing calculations on a model of a real 15 kV network with the neutral point earthed by a resistor. This analysis proves the practicability of the method both at the stage of designing power networks, and when a change in the neutral point earthing method in existing networks is being considered. Particularly valuable is also the statistical model of an earthing electrode resistance, developed on the basis of measurements in 2408 MV/LV substations, which may also be applicable in the future studies.

Повышение безопасности и эффективности электроснабжения участков добычи руд на высокогорном руднике

The results of study in the field of improving safety and efficiency of power supply to ore mining sites at a high mountain mine are presented. It is shown that safety and efficiency of power supply, as well as the hazard of electric shock in the electrical installations with a voltage of 6 kV, largely depends on the number of single-phase earth faults. It is established that high earth fault currents make it necessary to compensate for capacitive currents in 6 kV networks by installing compensating (arc-quenching) reactive coils. This will allow to reduce the ground fault currents to 3–5 A, increase the network insulation impedance by a factor of 4–6, reduce the over-voltages in the undamaged phases during ground faults, and improve conditions of ensuring electrical safety. It is substantiated that at the sections of the cable network leading to substations 25, 26, 28 and «Stvol», the resistance level is higher than the average for the high mountain mine, and in the sections of substations 31–35 and substation 33 it is slightly lower than the average. The worst state of insulation (maximum leaks) is observed at the sections of substations 31–106 and 31–34, where the insulation level is lower than the average by 16.6 and 3.56 times, respectively. It is recommended to carry out a preventive check of not only the condition of the cable, but also cable couplings, equipment at substations 31, 34 and 106 at these sites. And in the future, to continue study on high earth fault currents in the absence of control over the continuity of the earth network. Recommendations are given to improve the operation of electrical networks, to make fuller use of existing networks, and to ensure safe conditions for the maintenance of electrical installations of the networks with a voltage of 6 kV of the high mountain mine.

Electrical Shock Hazard Severity Estimation During Extravehicular Activity for the International Space Station.

INTRODUCTION: Research has shown that astronauts performing extravehicular activities may be exposed, under certain conditions, to undesired electrical hazards. This study used computer models to determine whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation.METHODS: A multiresolution variant of the admittance method along with a magnetic resonance image millimeter resolution model of a male human body were used to calculate the following: 1) induced electric fields; 2) resistance between contact areas in a Extravehicular Mobility Unit spacesuit; 3) currents induced in the human body; 4) the physiological effects of these electrical exposures; and 5) the risk to the crew during extravehicular activities.RESULTS: Using typical EMU shock exposure conditions, with a 15V source, the current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions during a spacewalk in the charged ionospheric plasma of space, astronauts could experience possibly harmful involuntary motor response and sensory pain nerve activation.Hamilton DR. Electrical shock hazard severity estimation during extravehicular activity for the International Space Station. Aerosp Med Hum Perform. 2021; 92(4):231239.

HVAC interference assessment on a buried gas pipeline

A pipeline, railway or telecommunication cable (referred to as victim line) sharing a common corridor with ac power transmission or distribution lines captures a portion of the electromagnetic field energy surrounding the power lines in the air and soil. This captured energy, often designated as ac interference, can result in an electrical shock hazard for people touching the victim lines or metallic structures connected to them. Furthermore, excessive stress voltages across rails, telephone pairs or pipe walls and coating surfaces can result in degradation or damage to equipment and puncture of pipe coating, leading to accelerated corrosion and can damage insulation flanges and rectifiers. The main objective for this study is to analyse proximity effect from a proposed double circuit transmission lines in different scenarios, which are steady-state, fault conditions and lightning strike. Induced voltage and currents on a gas pipeline to be determined using Current Distribution, Electromagnetics and Soil Structure Analysis (CDEGS) software.

Improved Earth Electrode Resistance for Utilizing Electrical Installations to Minimize the Hazard of Electric Shock

Resistansi pembumian di Laboratorium Instalasi Listrik Politeknik Negeri Bandung (Polban) sebesar 10,3 Ohm. Nilai tersebut melebihi standar maksimum menurut Persyaratan Umum Instalasi Listrik Tahun 2000 (PUIL 2000) yaitu maksimum 5 Ohm. Proteksi petir di Politeknik Negeri Bandung yang semula menggunakan sistem konvensional beralih ke sistem elektrostatis dikarenakan banyak kawat tembaga yang hilang sehingga banyak elektroda pembumian bekas proteksi petir konvensional yang tidak dipakai. Oleh karena itu elektroda pembumian tersebut bisa dimanfaatkan untuk memperbaiki nilai resistansi pembumian instalasi listrik. Hal tersebut menjadi latar belakang dalam penelitian ini yang bertujuan untuk memperbaiki nilai resistansi pembumian instasi listrik di Laboratorium Instalasi Listrik Polban sehingga bisa mengurangi bahaya sengatan listrik yang mungkin terjadi akibat kegagalan isolasi. Metode penelitian dalam penelitian ini adalah metoda eksperimental yaitu dengan melakukan pengukuran nilai resistansi pembumian instalasi listrik sebelum perbaikan dan setelah perbaikan dengan alat ukur Earth Tester. Perbaikan nilai resistansi pembumian instalasi dilakukan dengan cara menggabungkan elektroda pembumian bekas proteksi petir dengan elektroda pembumian instalasi listrik. Hasil yang dicapai dari penelitian ini adalah bisa memperkecil nilai resistansi pembumian instalasi listrik yang semula 10,3 Ohm sebelum perbaikan menjadi 1 Ohm setelah perbaikan, dan telah sesuai dengan Persyaratan Umum Instalasi Listrik Tahun 2000

An Enhanced Cassie–Mayr-Based Approach for DC Series Arc Modeling in PV Systems

DC series arc faults are known as a great threat in photovoltaic (PV) systems that may lead to fire and electric shock hazards. This article concentrates on driving effective models based on Cassie and Mayr equations for dc series arc using actual recorded data. Despite Cassie and Mayr equations that use invariant parameters during arc modeling, the proposed models employ the combinations of both Cassie and Mayr equations in which the time-variant nature of arc’s coefficients is taken into account. While the original Cassie and Mayr equations have two influential parameters for arc modeling, the first model presents a developed Cassie–Mayr equation with three parameters. Also, to further improvement in the model’s accuracy, the second model presents a developed Cassie–Mayr equation with five parameters. While the first and second models provide more prevision comparing with the original Mayr and Cassie–Mayr modeling, a third model is presented that treats with parameters of the original model as time-series parameters. To obtain the arc’s coefficients, a new formulation for coefficient estimation based on Levenberg–Marquardt (LM) algorithm is presented. Evaluating the proposed models with the actual recorded data, the results show the proposed models have more accuracy in comparison with the original Mayr and Cassie–Mayr.

The Prospect of HEF 4752 Chip Controller for Three Phase 24 Volt VSD Laboratory Training Set in Vocational Education

This study is intended to built a low voltage three phase 24/41 Variable Speed Drive (VSD) lab. experiment training set for vocational education institution with limited budged. The training set is cheap and save, both from electric shock hazard and for the electric measuring instrument, due to very low voltage used for running it. The three phase motor unit was build from redesigned of washing machine motor. The load of the motor is 736 grams silindrical iron with 5. 8cm diameter and 3.8cm of height. The VSD module designed for four step of speed controller in two mode of speed drives; V/F control and F control. Data comparison get from Schneider ALTIVAR ATV312H055M industrial standard for its voltage waves, and the character of V/F graphics measured in the lab. To make the same scale in MATLAB graphic pictures, the voltage of ALTIVAR 220/380V must be degrade by factor of 13. The results are; for F control only in HEF 4752 input terminal, the increasing of frequency still followed by the increasing of voltage in the motor terminal with more sloping curve rathen than V/F control mode. The slant of V/F control curve is the same in average fashion with that in ALTIVAR but the voltage waveshapes is denser in ALTIVAR. The slips of the motor are 31,5% - 8,3% in V/F mode control; 8,5% - 4,2% in F mode. With four steps speed; 40Hz, 44,44Hz, 57,14Hz and 65,57Hz; voltage gradation are 8; 9.7;11; and, 14 volts in V/F control and 11; 12; 13; and 14;volts in F control.

Early intervention mechanism for preventing electrocution in construction engineering.

The aim of this study is to establish an effective early intervention mechanism for construction engineering to prevent electrocution while improving labor safety and reducing the casualty risk. This study used narrative text analysis and the Haddon Matrix for data collection, and analyzed the causes from the 113 electrocution deaths among in the construction industry, the exhaustive chi-square automatic interaction detector algorithm was employed the segmentation of the correlations. Based on the theory of inventive problem solving, through IDEF0 (ICAM DEFinition) for function modeling was designed the early intervention mechanism. This study revealed the operating features related to electric shock hazards. Early intervention was introduced to reduce the relevant risks and establish safety mechanisms. The first contribution of this study is the determination of hazard correlations between operating features and conductive media, and entry point for the prevention of electrocutions. The second contribution is the suggestion of the establishment of inspection stations for electric tools, thereby ensuring that the portable power tools are safe. The final contribution is the joint application of TRIZ (Teoriya Resheniya Izobreatatelskikh Zadatch) and IDEF0, which establishing the pre-entry testing, strengthening safety mechanisms.

Safety Issues Referred to Induced Sheath Voltages in High-Voltage Power Cables—Case Study

Load currents and short-circuit currents in high-voltage power cable lines are sources of the induced voltages in the power cables’ concentric metallic sheaths. When power cables operate with single-point bonding, which is the simplest bonding arrangement, these induced voltages may introduce an electric shock hazard or may lead to damage of the cables’ outer non-metallic sheaths at the unearthed end of the power cable line. To avoid these aforementioned hazards, both-ends bonding of metallic sheaths is implemented but, unfortunately, it leads to increased power losses in the power cable line, due to the currents circulating through the sheaths. A remedy for the circulating currents is cross bonding—the most advanced bonding solution. Each solution has advantages and disadvantages. In practice, the decision referred to its selection should be preceded by a wide analysis. This paper presents a case study of the induced sheath voltages in a specific 110 kV power cable line. This power cable line is a specific one, due to the relatively low level of transferred power, much lower than the one resulting from the current-carrying capacity of the cables. In such a line, the induced voltages in normal operating conditions are on a very low level. Thus, no electric shock hazard exists and for this reason, the simplest arrangement—single-point bonding—was initially recommended at the project stage. However, a more advanced computer-based investigation has shown that in the case of the short-circuit conditions, induced voltages for this arrangement are at an unacceptably high level and risk of the outer non-metallic sheaths damage occurs. Moreover, the induced voltages during short circuits are unacceptable in some sections of the cable line even for both-ends bonding and cross bonding. The computer simulations enable to propose a simple practical solution for limiting these voltages. Recommended configurations of this power cable line—from the point of view of the induced sheath voltages and power losses—are indicated.

A novel intelligent detection schema of series arc fault in photovoltaic (PV) system based convolutional neural network

Series Arc Fault (SAF) can be defined as the failure that occurs between any electrical contact and any electrical circuitry. However, it considered one of the common failures that affect the operation of the PV system and causes serious problems such as fires and electrical shock hazards. Several reasons increase the possibility of this type of failures such as incorrect installation, irregular maintenance, and some environmental effects. This paper presents a new intelligent and accurate detection method of SAF in the PV system. In this method, Convolutional neural networks (CNN) which is a discriminative (supervised) deep learning algorithm used for the process of fault detection. In normal cases, the signal consists of DC component, inverter component and noise of Network. In the case of SAF, a new component will add to the signal; therefore, CNN used to discriminate against the new component to accurately detect the SAF. PSCAD is used to generate the Arc fault model; Performance evaluation and the results of the proposed method implemented using Python. The achieved accuracy of the proposed detection method is 98.9%. .

International space station spacecraft charging hazards: Hazard identification, management, and control methodologies, with possible applications to human spaceflight beyond LEO

In this paper, we present an overview of how the International Space Station (ISS) safety engineering methodology directed to controlling extravehicular activity (EVA) crew electrical shock hazards, caused by ISS spacecraft charging, has evolved over the past 25+ years. Long-term measurements of ISS charging severity and frequency-of-occurrence, combined with detailed probabilistic analysis of EVA electric shock-circuit completion, led to a change in hazard control methodology. The requirement for two-fault tolerant EVA shock hazard control during all EVAs was replaced with a less operationally burdensome and risky EVA shock hazard detection and warning process. The applicability of event probability-based detection-and-warning processes to human spaceflight charging hazard control beyond low-earth orbit (LEO) is also considered.

DC Autotransformer-Based Traction Power Supply for Urban Transit Rail Potential and Stray Current Mitigation

The rails are generally employed as the return path of traction current in urban rail transit. As the rails are not totally earth isolated, there exist the rail potential and stray current issues inevitably, which may lead to the electric shock, corrosions, and other hazards. In the past decades, different mitigation measures have been adopted to solve these issues. However, there are some limitations in the existing mitigation measures, such as poor performance, weak applicability, and so on. Therefore, the dc autotransformer (DCAT)-based traction power supply system is proposed in this article for the rail potential and stray current issues. The configurations, principles, and current distributions of DCAT system are analyzed in this article. Then, the comparisons between the DCAT system and the existing system for the rail potential and stray current issues are discussed, considering the different grounding schemes. Finally, the correctness and effectiveness of DCAT system on the rail potential and stray current issues are validated by both simulation and experimental results. Moreover, it is shown that DCAT system transfers the traction current from the rail to other lines and solves the rail potential and stray current issues much effectively.

Measures to Minimize Series Faults in Electrical Cords and Extension Cords

In electrical power systems, cords and extension cords are exposed to mechanical damage and other insulation stresses. Mechanical damage to stranded conductors can reduce locally their cross section or break them and cause anomalous local conditions of overheating or arcing. The ordinary protective devices cannot detect the series faults that persist, so the fault point remains energized and is subject to electric shock and fire hazards. Effective protection can be accomplished by implementing active and passive measures: installing arc-fault circuit interrupters or arc-fault detection devices, able to detect arcing faults, or wiring the circuits with a grounding protection conductor to involve the ground in every fault. In this way, residual current protective devices (residual current devices or ground fault protective devices) quickly protect the series faults not only with arc, but also without it. Ground-fault-forced cables facilitate by design the conversion of any kind of cable fault to a ground fault. They are particularly recommended for cords and extension cords, internal circuits to grounded equipment, uninterruptible power system continuity circuits, aircraft circuits, road tunnels, data centers, refrigerated containers parks, residences, and hospitals.

Two‐/three‐coil hybrid topology and coil design for WPT system charging electric bicycles

Wireless power transfer (WPT) for charging electric bicycles (EBs) can save people from tiresome plugging actions and avoid electrical shock hazards, especially in adverse weather. This study proposed a two-/three-coil hybrid topology to achieve constant current (CC) and constant voltage (CV) for charging EBs, simplifying control schemes. The system realises CC output with two-coil topology and operates in CV mode with three-coil topology by turning on a switch. Besides, an inductor array is used to compensate reactive power in CV mode when massive EBs are charged by one high-frequency inverter (HFI). The secondary side of the proposed topology is compact, and the number of components and HFI can be reduced. A coil design process based on double-D-type for the three-coil system is given, with the constraint of mutual inductances among three coils and limited size. To demonstrate the validity of the proposed methods, an experimental setup is built, and the performance of the two-/three-coil hybrid system indicates that the fluctuations of charging current and voltage are <0.64 and 2.12% in the whole charging profile. Moreover, the performance of two WPT chargers connected with one HFI hints that massive EBs can be charged with only one HFI.

Cost‐effective inductive power transfer charging system for electric bicycles with variable charging current using primary‐side detuned series‐series topology

Due to the convenience and long travelling distance, electric bicycles (EBs) are becoming more and more popular. Charging EBs with inductive power transfer (IPT) technology can free people from wearisome plugging actions and avoid electric shock hazards. However, the cost, including component cost and control cost, is a big challenge for the extensive promotion of the IPT charging systems (IPTCSs) for EBs. This article proposes an IPTCS using primary-side detuned series-series (SS) compensation topology, cancelling control scheme and reducing the component cost. With the proposed parametric design method, the IPTCS can operate with variable charging current according to the variable equivalent resistance of a battery. Besides, the inductive input impedance is guaranteed to achieve soft switching for the high-frequency inverter. An experimental setup is constructed to validate the proposed method. The performance shows that the charging current decreases from 1.8 to 0.1 A, and charging voltage increase from 42.23 to 54.01 V during the whole charging process, where the maximum efficiency of the IPTCS can reach up to 92.8%. The results demonstrate the proposed IPTCS is a cost-effective and potential solution for charging EBs.