Arc Flash Incident Research Articles

Methods for Evaluating DC ARC-Flash Incident Energy in Battery Energy Storage Systems

Methods for Evaluating DC ARC-Flash Incident Energy in Battery Energy Storage Systems

Extending the Life of Low Voltage Adjustable Speed Drives: The Newest Technology to Eliminate Risk

A fundamental aspect of low voltage adjustable speed drives’ (LV ASDs’) overcurrent protection is the elimination of harmful input power anomalies that could significantly damage the sensitive electronics in and around the ASD. This article provides an overview of the newest LV solid-state circuit breaker (SSCB) technology and how petroleum and chemical industry users can take advantage of its ability in eliminating almost all the electromechanical stresses applied at the input to any LV ASD when protected with traditional circuit breakers or high-speed protective fuses. This higher level of protection comes through the use of SSCB technologies that provide the lowest let-through energy level of any overcurrent protective device available today. At the same time, these devices eliminate risk by reducing harmful arc flash incident energy to near-negligible levels while requiring no maintenance.

Flash Intensity of Arc, Isoflashes Distribution, and Body Surface Area

The empirical model of IEEE Standard 1584 defines arc flash incident energy and arc-flash boundary. This article assumes as reference the empirical model that compares with the spherical model of the incident energy emission and classifies the deviations. The new approach allows a physical approach to the phenomenon, to identify characteristic parameters as the arc flash intensity, and to analyze the distribution of the incident energy applying the “point-by-point” method on flat surfaces exposed to arc flash, as a simulation of the human body. This method allows us determining isoflash surfaces that collect points at different distances in the space, allows us characterizing the behaviors of electrodes configurations and estimating the prospective body surface area affected by lesions.

Application of Time-Voltage Characteristics in Overcurrent Scheme to Reduce Arc-Flash Incident Energy for Safety and Reliability of Microgrid Protection

The interconnection between diverse Distribution Generations (DGs) that utilize various technologies and complex structure of networks are the most characteristic of modern Distribution Networks (DN). The wide adoption of DGs considerably affects the power flow dynamics in the DN and consequently the fault characteristics. The excessive level of fault currents can pose risks of heat (high temperature) and pressure in accordance to Arc Flash (AF) incident energy in microgrids. This research studies the relationship between AF severity and the solving of coordination problem of Overcurrent Relays (OCRs) in DN, and introduces a novel equation that considers the AF qualities in solving the coordination problem for OCRs. In this study, a novel optimization problem, the AF severity with the optimal coordination of OCRs in DN is presented and the Water Cycle Optimization Method (WCOM) is employed to find the best combination of the OCR’s settings in the DN while considering the AF induced energy. The proposed optimization approach and the novel equation are evaluated with an IEC microgrid and compared with the conventional protection method and Particle Swarm Optimization (PSO) used in optimizing the coordination of OCR in the DN. The optimal settings of the OCR scheme are achieved and examined on the modified IEC microgrid benchmark system. In order to verify the result, an industrial simulation package (ETAP) and OCR (GE Multiin, model-750/760) was used in this work.

Arc-Flash Incident Energy Analysis: Renewal Recommendations

Generally accepted industry standards, such as National Fire Protection Association (NFPA) 70E-2018, require arc-flash incident energy analysis to be updated when changes occur in the electrical power distribution system, and the analysis shall be reviewed for accuracy at least every five years. NFPA 70E also requires the data used for creating equipment labels, which contain arc-flash energy information, to be reviewed at least every five years, and, if the review identifies a change that renders the arc-flash energy label inaccurate, the equipment label must be updated.

Complacency is Your Enemy: Anatomy of an ARC Flash Incident and Lessons Learned

On May 3, 2015, a serious electrical incident occurred at one of the Department of Energy's national laboratories. Preventative maintenance was being performed on 13.8-kV switchgear, which included the task of cleaning individual switchgear cubicles. A wireman unknowingly entered an energized cubicle in order to clean it with a commercial spray cleaner. When he proceeded to spray the cleaner onto the energized components, he suffered severe injuries from the resulting arc flash and blast. This article will breakdown the discussions, thought processes, and planning decisions that were made from both the facility and worker's perspective. It will describe risk factors that increased the likelihood of this incident and breakdown how the addition of a single risk control measure could have prevented this incident. Finally, it will describe the details leading up to the incident, the incident itself, the response, and lessons learned. The lessons learned associated with this incident emphasizes the importance of using tools to promote active thinking during both the planning and execution of the work in order to reduce the likelihood of human errors associated with complacency.

Determine the Electrode Configuration and Sensitivity of the Enclosure Dimensions When Performing Arc Flash Analysis

Arc flash hazard prediction methods have become more sophisticated because the knowledge about arc flash phenomenon has advanced since the publication of IEEE Std. 1584-2002. The IEEE Std. 1584-2018 has added parameters for more accurate arc flash incident energy (IE), arcing current, and protection boundary estimation. The parameters in the updated estimation models include electrode configuration, open circuit voltage, bolted fault current, arc duration, gap width, working distance, and enclosure dimension. The sensitivity and effect changes of other parameters have been discussed in the previous literatures. This article explains the fundamental theory on the selection of electrode configurations and performs sensitivity analysis of the enclosure dimension that have been introduced in the IEEE Std. 1584-2018. According to the newly published model for IE estimation, the IE between vertical conductors inside a metal box (VCB) and horizontal conductors inside a metal box (HCB) can differ by a factor of two with other parameter constants. Using HCB as the worst-case scenario to determine the personal protection requirements may not be the best practice in all circumstances. This article provides guidance for electrode configuration selection and a sensitivity analysis for determining a reasonable engineering margin when actual dimension is not available.

Measurement of DC Arc-Flash Incident Energy in Large-Scale Photovoltaic Plants: A Basis for Standardization

Measurement of DC Arc-Flash Incident Energy in Large-Scale Photovoltaic Plants: A Basis for Standardization

Selective Coordination and its impact on Low Voltage System Design & Arc Flas h

This paper focuses on total selective coordination of low voltage systems for critical facilities and based on reliability requirements. Critical facilities which include Data Centres, Health Care Facilities & Emergency Systems. It also discussed the importance of achieving total selective coordination and the impact on network design and how it is related to arc flash incident energy. It also states the National Electric Code requirements for the implementation of selective coordination based on system reliability requirements. The difficulties in achieving selectivity from Grid side and an inhouse generation side and the reliability benefits on critical facilities are discussed.

Introduction to IEEE Standard 1584: Guide for Performing Arc-Flash Hazard Calculations, 2018 Edition

Since it was first published in 2002, IEEE standard 1584 has been the premier standard for arc-flash hazard arcing current, incident energy, and arc-flash boundary (AFB) calculations for an arc-flash incident. After extensive testing and model development and a validation period, the long-awaited revision of IEEE 1584 has been published. The purpose of this article is to introduce IEEE Standard 1584-2018, IEEE Guide for Performing Arc-Flash Hazard Calculations , to the industry. The model range and the rationale used for parameter selection is discussed for quantities such as voltage, bolted root-mean-square (rms) short circuit current, the gap between conductors, enclosure dimensions, fault duration, working distance, and system frequency. The rationale is provided for the selection of electrode configurations and various enclosure (box) sizes and arrangements. This model is based on more than six times the tests performed for the model used in the 2002 standard. It provides additional modeling of electrode configurations which were not included in the 2002 version. Some guidance on identifying electrode configurations is provided.

Methods of determining safety boundary and PPE by analysing arc-flash incident energy in medium voltage panels

Arc-flash events still occur frequently in industries especially in Indonesia and there are many operators and technicians have got burn injuries caused by it. To avoid this accident, this paper discus about arc flash and its incident energy as well as personal protective equipment (PPE) should be worn by those working with electric panels (switchgears). To demonstrate how incident energy is calculated and the protection boundaries are determined, a 6 kV, 3750 kVA utility panel in a geothermal power plant (60 MW) is used as object. The steps have to be done in this research are bolted fault current and arc fault current calculations, calculation of incident energy and determining both protection boundaries and the relevant PPE. As result, it is found that with protection setting clearing time of 0,12, the incident energy is 4,418 J/cm2 and the protection boundary is 1.4 m. The danger will increase with longer clearing time of relay or closer distance to the panel. This paper will hopefully be very help full for the responsible engineers to analyse the danger of any kind of panels and to determine PPE for workers.

Measured and Calculated DC Arc-Flash Incident Energy in a Large-Scale Photovoltaic Plant

There is a growing amount of high-power dc equipment being deployed, including solar photovoltaic (PV) plants, but very few studies have measured and quantified dc arc-flash risks. Most dc arc-flash literature is based on the theory and, when their theoretical calculations are applied to real-world conditions, can significantly deviate from actual measured values. For PV, the non-linearity of the power source (i.e., PV modules) creates an additional level of uncertainty for theoretical approaches. This paper quantifies the thermal hazards from arc flash in a real-world 1000-kWdc PV plant by measuring arc current, arc voltage, and incident energy (IE) and then compares results against existing IE models. The study reveals that none of the available models adequately represent real-world hazards. It is also found that a PV source acts as a sustainable constant-current source during an arc-flash event. This paper is an important first step toward developing an improved model that more accurately assesses dc arc-flash risk in a PV system.

Impact of Distributed Energy Resources on Arc Flash Incident Energy

Electric line personnel perform energized overhead line work and expose themselves to potential arc flash burns. Arc flash incident energy is calculated to determine proper personal protective equipment to protect line personnel against bodily injuries. As increased amount of distributed energy resources (DERs) are being interconnected to distribution systems, higher arc flash incident energy is encountered. This paper explores the arc flash incident energy calculation method for distribution overhead feeders with the presence of DERs. The impact of DERs on arc flash incident energy is evaluated on nine Dominion energy's distribution feeders that interconnect solar inverters. Various factors, including DER mega volt-ampere (MVA) capacity, DER unintentional islanding run-on time, and DER step-up transformer winding configuration are considered. The effectiveness of neutral grounding resistors and low set instantaneous protection is also explored.

Transformer Energization From Low-Voltage Side With Limited Generation—Power System Constraints and Protection Considerations—A Case Study

A large existing delta-wye step-down transformer was proposed to be temporarily used as a step-up transformer and energized from the low-voltage wye winding by multiple small diesel generators (DGs) to accelerate commissioning activities by utilizing existing temporary generation. This paper is a case study that discusses the associated power system constraints created by this proposed modified power system configuration. The modified power system configuration resulted in an ungrounded high-voltage (HV) system created by the transformer's delta winding, which required HV system modifications to create a grounded system. Additionally, the existing power system had generation and load flow constraints and had protection and coordination constraints that needed to be maintained to supply the existing loads. Also, the inrush current resulting from the transformer energization needed to be evaluated and compared with the generator's short time current rating. Finally, modifications to the protection and coordination settings resulting from the modified power system configuration and confirmation that the arc flash incident energy levels were acceptable after implementation of modified settings were required.

Reducing Arc-Flash Hazards: Installing MV-Controllable Fuses on the Secondary Side of the Transformer in a Pumped Storage Plant

The Mitigation of arc-flash incident energy is important to increase safety. One method is to reduce the duration of the arc flash by using protective relays to sense an arc-flash fault. This method requires a supply-side switching device that will respond to the protective relaying fast enough to mitigate the incident energy. In many existing installations, medium-voltage (MV) controllable fuses are already installed to provide transformer protection. Before the development of an MV-controllable fuse, the MV fuse would have to be replaced with an MV circuit breaker or circuit switcher to have relay control of the MV protective device. This replacement would have significant equipment and construction costs and require extensive equipment outage time. The MV-controllable-fuse method uses the existing fusegear protecting the primary side of the transformer. The protective relay senses the arc fault and signals the controllable fuse to change to a fasteracting time-current response. The incident energies can be reduced from 200 cal/cm2 to lower than 8 cal/cm2 on the secondary side of the transformer. This article reviews an installation using an MV-controllable fuse to mitigate the incident energy on the equipment connected to the secondary side of the transformer.

Arc-Flash Mitigation: A Systematic Approach for Company Standard Power System Schemes

Arc-flash hazard assessment studies involving a very large oil and gas company's equipment rated 38 kV and below revealed locations with excessive arcflash incident energy. After conducting many additional studies of power distribution systems for various plants (e.g., refineries, gas plants, gas-oil separation plants, and natural gas liquid plants), we realized that dangerous locations (greater than 40 cal/cm2) are somewhat consistent among various plant types. This knowledge makes planning and budgeting for implementing arc-flash mitigation predictable from a corporate perspective. Specific arc-flash mitigation techniques can be embedded in the specifications of new projects as well as company material standards to avoid unnecessary retrofit activities after installation. Maintenance personnel can also be effectively trained on arc-flash mitigation and safe work practices when consistent solutions are implemented. This article demonstrates a systematic approach to address dangerous arc-flash locations for corporate planning purposes and provides practical mitigation solutions that can be applied at many company facilities.

Arc Flash Pressure Measurement System Design

Pressure waves from the arc flash incident may pose significant risks to the workers. It is imperative to develop industry safety standards to protect workers from these pressure hazards. Due to the harsh conditions during arc flash, it is difficult to apply traditional pressure measurement methods to obtain accurate pressure data for standard development. Currently, much qualitative or vague quantitative information are widely mentioned or misused among industry. For example, 2100 psi has been mentioned in several arc flash-related articles without detail description about measurement environment or the operation conditions. This paper explores different pressure measurement devices and techniques to overcome the limitations of traditional approaches, including pressure transducers, pendulums, and linear-variable displacement transducers (LVDT) to obtain reliable results under harsh conditions. It is desired to have techniques that are capable of measuring the pressure level of the arc flash as perceived by workers. The air speed estimated from consecutive frames of high-speed video is used as a bench mark to compare the results from different techniques and devices. These results offer valuable information to develop reliable system and techniques to evaluate the potential of pressure hazards during an arc flash.

Touch Voltage Analysis in Low-Voltage Power Systems Studies

The touch voltage analysis in low-voltage installation, i.e., the calculation of magnitudes and durations of touch potentials, is not normally included in standard power systems studies. In addition, this analysis is of paramount importance for the protection of persons against electric shock in the event of failure of basic insulation of equipment or of direct contact with live parts. Even in correctly designed and erected installations, the risk of electric shock is present, and its amount can only be quantified through the determination of the exposure to touch voltages. This paper will provide equivalent fault-loop circuits and application formulas for the determination of touch voltages, in light of permissible safe values as calculated per IEEE and IEC standards. These authors support the importance and necessity of the touch voltage analysis, as a fundamental component of the “Designing for Safety” approach, and propose their inclusion in system studies as a routine procedure, as it is similarly done for arc flash incident energy calculations.

The Effects of System Grounding, Bus Insulation, and Probability On Arc Flash Hazard Reduction—Part 2: Testing

This paper provides a follow-up to the paper The Effects of System Grounding, Bus Insulation and Probability on Arc Flash Hazard Reduction—The Missing Links . In that paper, system grounding and bus insulation were considered a means of reducing the probability of an arc flash incident by approximately two orders of magnitude. In September 2013, additional testing was conducted on a low-voltage motor control center (LVMCC) with the expectation that engineering enhancements such as insulated vertical bus, high resistance grounding, and other techniques could be implemented to further reduce the probability of an arc flash incident. The testing performed was with faults initiated in locations typically found in operating petrochemical facilities, in LVMCCs, with the starter unit door open. This paper discusses the findings of testing on real-world electrical equipment in an effort to further understand and minimize the probability of an arc flash incident. This paper reviews the physics of the arcing fault and how ignition wire, geometry, and the number of anode/cathode pairs all contribute to arcing fault energy and personnel exposure.

Arc Flash Mitigation Using Active High-Speed Switching

One method of mitigating arc flash hazards associated with medium-voltage switchgear is the installation of active high-speed switch (HSS) systems. These systems are designed to detect and quench a burning internal arc in less than one-third of one electrical cycle. The internal arc is extinguished by the HSS's action of redirecting the fault current path from arcing through open air back to the intended current path of the switchgear bus. The new low-impedance current path provided by the HSS operation collapses the voltage at the point of the fault to near zero so that the arc is no longer sustainable. The system's high speed of operation compared to arc quenching via circuit breaker tripping translates directly to lower arc flash incident energy and minimal equipment damage. Another benefit of such active high speed systems could include switchgear compliance to the IEEE C37.20.7 guide for testing arc-resistant metal-enclosed switchgear without any arc by-product venting requirements. This paper explores application considerations of HSS systems relative to other available means of controlling and reducing the hazards of internal arcing faults in medium-voltage switchgear.