Arc Flash Event Research Articles

Learnings From a 480-V Arc-Flash Event: Poor design, inadequate maintenance, insufficient training, and wrong ppe results in injury

Learnings From a 480-V Arc-Flash Event: Poor design, inadequate maintenance, insufficient training, and wrong ppe results in injury

Integral Protection Methodology to Mitigate Incident Energy

This paper proposes a new integral methodology to overcome hidden failures and mitigate the electrical hazard due arc-flash events. This methodology overcomes the drawbacks of legacy protection functions due hidden failures. Also, considering the requirement to limit the maximum arc-flash hazard, a restriction has been implemented to coordinate the protection devices in the proposed methodology. The application results of the proposed methodology are shown on a steel manufacturer user showing the improvements by reducing the probably incident energy feasible due to arc-flash events and show how legacy protection functions would fail to operate in such scenario.

PREVENTING AND MINIMIZING ARC FLASH RISK IN POWER SYSTEM NETWORK

Arc flash events have resulted in several accidents due to faults in electrical equipment that lead to a significant release of energy. This event is a hazard and threat to the Power System Security and due to the large energy release, plasma is generated, as pressure increases since it causes physical damage to equipment while life of system operators within the vicinity of its occurrence are at risk. Although arc flash is one of the electrical safety programs that have been in existence, arc flash hazard was not adequately addressed until recently. However, the Electric Arc phenomenon is relatively new in the Nigerian power industry, there are certain aspect that are yet to be treated by the available literature, hence it is the duty of this work to establish model for addressing the observed lapses. The design is adequately prepared for the power system security analysis using typical scenarios in industrial facilities that are prone to yield high incident energy levels. In line with the foregoing, the developed methodology is validated using a segment of the Nigerias power industry as case study.

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.

Failures of Equipment Operating Under Normal Conditions: Arc-Flash Events can Happen during Normal Operation

Informational Note No. 1 for the definition of arc-flash hazard in National Fire Protection Association (NFPA) Standard 70E-2015 states, Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc-flash hazard. Table 130.7(C)(15)(A)(a) of the standard instructs that arc-flash personal protective equipment (PPE) is not required for normal operation of a circuit breaker, switch, contactor, or starter if the equipment is properly installed, properly maintained, equipment doors and covers are closed and secured, and there is no evidence of impending failure. This article reviews three electrical equipment failures during substation circuit breaker operations where if personnel had followed the guidelines just described, they could have been seriously injured during these failures due to the arc-flash energy released at the time of the fault.

Comparative Analysis of Experimental DC Arc Flash Results to Industry Estimation Methods

With the utilization of DC systems increasing, and constant emphasis for worker safety as a top priority for all companies, arc flash feasibility for DC systems is a growing concern. This article details the feasibility of DC arc flash events with experimental scouting tests for a 130 VDC system. Sensitivity studies are experimentally performed on the impact of bus gap distance and bolted fault current level on incident energy. Test results are analyzed and conclusions drawn on the results, in particular incident energies. Details of the tests performed including the setup, procedure, and system parameters are also provided. Theoretical methods of determining incident energy for the testing conditions are also explored. Specifically, these are Doan's and NFPA 70E's maximum power models, and Stokes and Oppenlander's and Paukert's arc resistance models. A comparative analysis of the test results to industry standard, NFPA 70E, and software analysis methods using ETAP, an industry leading software used for arc flash studies, is performed.

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.

Arc Flash Visible Light Intensity as Viewed From Human Eyes

Human eye can be damaged by the intense light from an arc flash event. Though it is certain that high intensity visible light will be emitted during an arc flash event, there is limited research that provides quantitative light intensity estimation during different arcing incidents as viewed from human eyes. To provide better understanding of the light intensity during arc flash events, this paper proposes an arc flash light intensity estimation model based on approximately 1500 measurement data from arc flash tests using ambient light sensors, which are capable of measuring the light intensity of the arc flash as perceived by the human eyes. The proposed light intensity estimation model can be used to evaluate the potential impact of an arc flash on the human eyes. In addition, the autodarkening welding lens is used in the arc flash testing to explore its effectiveness in attenuating the light intensity and mitigating the exposure to the light hazard during an arc flash event.

Fiber-optic arc flash sensor based on plastic optical fibers for simultaneous measurements of arc flash event position

We present an arc flash sensor that can trace the arc event position as well as intensity by utilizing conventional plastic optical fibers (POFs). In order to check the possibility as a light-receiving sensor, we experimentally confirm that the externally irradiated flash light can be coupled into the fiber core through the surface of POF without any additional treatment. After the incident light is divided in two optical paths toward opposite directions, they have the different attenuation values determined by the propagation distance. Since the optical transmission loss of a POF is constant regardless of the irradiated energy, the intensity ratio for two signals measured at both fiber ends is given as a function of position. The experimental results show that we can successfully trace the event position from this intensity ratio. In addition, it is possible to define the illuminated energy by comparing the absolute value of the intensity measured from one side. According to the experimental results, the proposed sensor has a relatively fine spatial resolution, ±10 cm, despite having a simple structure.

Novel Approach to Arc Flash Mitigation for Low-Voltage Equipment

As industry pursues safer workplaces with arc flash mitigation programs, they face major challenges in effectively reducing incident energies on the secondary of medium-voltage to low-voltage (MV-LV) transformers. When an arc fault occurs on the transformer secondary, primary currents can be below the short-circuit range of the primary protection. Typical E-rated fuses can take over 2 s to clear, while high-side device 51 relays will have a waiting period before initiating a breaker trip. Solutions that adjust the LV main breaker's (if applied) protective functions for faster response do not address arc fault issues on the bus connecting this main breaker to the transformer secondary. This paper presents a method of applying a high-speed grounding switch at a location between the MV E-rated fuse load terminal and the transformer's primary connection. Since the transformer's primary voltage is reduced to zero in milliseconds, the low-voltage arc flash event collapses quickly to limit incident energies to less than 1.2 cal/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Applications can include MV-LV transformers up to 5000 kVA.

플라스틱 광섬유 표면 입사 현상을 이용한 아크플래시 검출 광센서

Abstract In this work, a loop sensor for Arc-Flash detections has been developed in order to trip a circuit breaker within 2.5 ms after an Arc-Flash event. For an efficient capturing of the flash light, plastic optical fibers, where light attenuations are larger than those in silica-based ones, with different diameters and surface conditions were utilized. The performance was comparatively analyzed with those ofa point sensor and a commercialized product. The point sensor module was designed for hemisphere-like capturings of Arc-Flasheslarger than 3 kA at 2 meters from the sensor. On the other hand, the loop sensor allowed 360-degree-detections around the fiber axisand the measurement range was dependent on the length of the fiber connected to the sensor module. The trip-level-dependent bright-ness measurement results showed that the fabricated point sensor and loop sensor satisfied a brightness condition, 10~40 klux, and theresponses of the system to Arc-Flashes were completed within 2.5 ms.Keywords: Arc-Flash sensor, Plastic optical fiber, Protective relay

New Preemptive Arc-Fault Detection Techniques in Medium-Voltage Switchgear and Motor Controls

For forest-products-based industries, the significant benefits of preemptive arc-flash protection and online condition monitoring of electrical equipment are not well known. This paper provides a summary of the research surrounding the development and testing of new advanced sensor technologies for this purpose. This paper builds on the authors' initial research and their supporting publications providing more extensive and detailed field measurements supporting the preemptive detection of significant defects that can lead to an arc-flash event. The early detection of impending faults and the prediction of future arc-flash occurrences in medium voltage (MV) switchgears and motor control centers (MCCs) can be very beneficial. The development of new sensor technologies both for partial discharge measurement and thermal detection are discussed and evaluated. The two most common noncontact causes leading to an arc-flash event in MV switchgears and MCCs are insulation degradation and thermal stresses. This paper will highlight very detailed results measured under both of these conditions in laboratory and actual installed conditions. An effective signal processing method, which is used for extracting the essential indication data and for the integration of this system into existing protection programmable logic control or supervisory control and data acquisition (SCADA) systems, is outlined.

Exposed to the Arc Flash Hazard

It is widely acknowledged that an arc flash hazard may exist when energized conductors are within equipment in an enclosed condition if a person is interacting with the equipment at close proximity in such a manner that could cause an electric arc fault. This paper presents the results of scouting tests of arc flash events within enclosed low-voltage equipment (internal arc faults). This testing was performed to see if the incident energy mitigation efforts of one company were adequate to prevent arc flash exposures to equipment operators should an arc fault occur within the equipment they interact with. Arc faults were initiated within low-voltage disconnect switches, industrial control enclosures, and motor control center (MCC) buckets. Only the possible severity of such events on nearby operators was investigated. No attempt was made to identify the likelihood of such events from operator interaction, nor all of the potential causes of internal arc faults.

Preemptive Arc-Fault Detection Techniques in Switchgear and Controlgear—Part II

The significant benefits of preemptive arc-flash protection and the online condition monitoring of electrical equipment are quite well known. Our continuing research focuses on the development of new advanced sensor technologies that are cost-effective, reliable, and efficient for the early detection of faults in order to predict impending arc-flash occurrences in mediumvoltage and low-voltage switchgear and controlgear. More extensive and detailed measurements regarding significant defects that lead to an arc-flash event have been completed since the original work in Part I was completed. A more detailed analysis of the results of this additional testing is presented in this paper. It has been documented that the two major noncontact causes that lead to an arc-flash event in switchgear are insulation degradation and thermal stresses. This paper covers the detailed measurement results under both of these conditions. New sensor technologies for both the partial discharge measurement and the thermal detection are introduced and evaluated. An effective signal processing technique, which is needed for extracting the essential indication of a developing fault, is also presented. Finally, this paper outlines how a preemptive arc detection system can be connected to protection, the programmable logic controller, or the supervisory control and data acquisition.

Managing Arc Flash: Collaborative Solutions in Medium-Voltage Switchgear

Many articles have been written about arc-flash events, mostly with a single focus. This article brings forth a wider view with a time/distance analysis of different arc abatement technologies in medium-voltage, metal-clad switchgear. The IEEE C37.20.7 [8] actual test results data, obtained from a certified high-voltage test facility, offers the reader a true snapshot of pressures developed within standard metal-clad switchgear enclosure using the latest blend of arc abatement topologies. Comparisons are made between the three prevalent technologies, which address an arc flash by time-magnitude approach boundaries. This article also addresses the phenomena associated with electrical arcs within medium-voltage switchgear by developing an introductory understanding of the generation of an arc and the pressure damages that both equipment and personnel may encounter.

Impact of Arc Flash Events With Outward Convective Flows on Worker Protection Strategies

Recent research into arc flash test configurations suggests that some equipment may have the potential for greater arc flash incident energy than that predicted by IEEE 1584 due to outward convective flows associated with electrode orientation and configuration. This research suggests that lower arcing currents could lead to longer clearing time of protective devices and higher incident energies. Additional research also suggests that flame-resistant materials used in electrical personal protective equipment (PPE) may not provide the same protection levels as predicted by their arc rating when placed within these convective flows. The possible impact on protection requirements, work procedures, and mitigation strategies of these findings is discussed. This paper looks at the impact of adjusting the Cf factor of the IEEE 1584 incident energy equation to accommodate test data from alternate configuration, using lower IARC and derating the arc rating of PPE.

Shrapnel, pressure, and noise

The noise hazard associated with an arc-flash event requires the use of personal hearing protection devices (PHPD) when workers are exposed to an arc-flash hazard. Arc-rated hoods can provide some protection for the noise hazard and can be used in conjunction with PHPDs to provide hearing protection. Although it is not possible to quantify the shrapnel hazard associated with an arc-flash event the ballistic protection offered by the arc-flash PPE to standardised threats can be determined.