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A Study of Arcing Fault in the Low-Voltage Electrical Installation
Abstract
Currently there is technology capable of detecting arcing conditions in low voltage installations available in the United States and Canada (120 V, 60 Hz). This technology has been developed to increase the protection of those installations against electrical fires. While there is a great interest to apply this technology to higher voltage applications (230/240 Vac, 50/60 Hz) it is important to understand how safety-related requirements might need to change in order to be applicable to these new conditions. This discussion covers aspects governing standard testing methods utilized in the industry, the operational environment of the technology and the need for means that realistically could duplicate a series arc fault in order to have a better understanding of the driving factors impacting both applications. The author suggests an implementation method that can be used as an alternative means of testing which provides a better observation of the occurrence, the stability and the outcome of series arcing.
... The detection of arc phenomena in domestic electrical installations is essential for home safety [1]. Many reports show that a significant number of fires are related to electrical problems (overcurrent, short circuit, insulation worst fault gold contacts, etc.) [2]. ...
... Protective devices (arc fault circuit interruptor, AFCI) are placed upstream the power line, and the detection is often undertaken from the analysis of voltage and mainly the line current [1,3,4]. ...
... The first detection algorithm is based on the correlation and the second on the evolution of the crest factor. The circuit considered is that of combined loads in the presence of an electric arc in series in the line, a configuration for which the detection is more difficult to achieve [1,[12][13][14][15][16][17][18][19][20]. ...
Electrical arc fault detector development requires many tests to develop and validate detection algorithms. The use of artificial intelligence or mathematical transformation requires the use of consequential datasets of current signatures corresponding to as many different situations as possible. In addition, one of the main drawbacks is that these experiments take a great deal of time and are often laborious in the laboratory. To overcome these limitations, a virtual test bench based on the modeling of a modular 230 VAC electrical circuit has been developed. The simulated network is composed of different home appliances (resistor, vacuum cleaner, dimmer, etc.) and its configurations are those of single and combined loads. The fault modeled is an electric arc, modeled by active diode switching, which can be inserted at any point of the circuit. This arc model takes into account the random variations in the restrike and arc voltage. All the appliance models are validated by comparing the frequential (harmonic distortion) and temporal (agreement index) signatures of the measured currents in real situations to those obtained by modeling. The results obtained using the model and experiment network show that the current signatures are comparable in both cases. Further, two detection algorithms are tested on those current signatures obtained by the modeling and experimentation. The results are comparable and provide identical detection thresholds.
... A detecção do arco não é uma tarefa trivial, tendo relação com o percurso da corrente de falta arco. A partir deste critério a falta arco pode ser classificada como falta arco série e falta arco paralelo, conforme mostra a Figura 2 [11]. Com base na Figura 2 pode-se constatar que a corrente do arco tipo série tende a ser menor do que a do arco paralelo, pois está limitada à corrente de carga. ...
... Existem modelos matemáticos que são utilizados para simular este tipo de fenômeno, balizando a execução de experimentos exploratórios [36]. Considerando as características elétricas do arco falta, o mesmo pode ser representado através de um circuito elétrico equivalente mostrado na Figura 4 [11]. Existem ainda modelos mais simplificados capazes de reproduzir de maneira satisfatória o evento, sendo possível perceber claramente os distúrbios gerados nos diferentes níveis de detalhamento da decomposição com a transformada Wavelet [35]. ...
... Circuito elétrico equivalente da falta arco série. Adaptado de[11]. ...
... Parallel-arc faults can either occur due to over currents or due to heavy earth leakages, both of which can be detected by conventional protection devices such as MCB and RCD. as shown in Fig. 2. However, in the case of seriesarc faults, there will not be any significant overcurrent or any leakage current [7]. If the series-arc current lies below the rating of the MCB, which is usually the case, the MCB will not detect any overcurrent [7]. ...
... However, in the case of seriesarc faults, there will not be any significant overcurrent or any leakage current [7]. If the series-arc current lies below the rating of the MCB, which is usually the case, the MCB will not detect any overcurrent [7]. It is also not a leakage current, so that the RCD will not detect it either [2,8]. ...
The main cause of electrical fires, which is more severe in nature than non-electrical fires, is the series-arc fault. In this paper, the properties of series-arc faults are studied and the parameters affecting the risk of domestic electrical fires are analysed. In particular, a series-arc fault generator, made to align with the international standards, is used to study the characteristics of series-arc faults in a domestic electrical installation. The waveforms of common domestic equipment, in the absence of a fault and in the presence of a fault, are examined in detail. It is seen that arc current waveform can be identified as having a vertical edge appearing after the zero-crossing point. Further, the impact of series-arc faults on igniting a fire in domestic electrical installations are analysed using thermal imaging. Finally, ability of the most commonly used insulation materials which may aid the initiation of electrical fires due to the series-arc faults has thermally categorized. The study has shown that even a 2A arc current that is sustained for 2s can auto-ignite PVC, the most common insulation material in domestic installations.
... Restrepo [62,97] et Martel [95] proposent l'analyse du courant en haute fréquence en utilisant un transformateur toroïdal à ferrite centré autour de la fréquence de 22 MHz. ...
... Restrepo [62,97] ainsi que Martel et al [95] présentent une méthode de détection basée sur l'analyse de l'énergie de l'arc, il propose de détecter la présence d'un arc en se concentrant sur le bruit haute fréquence dans une bande centrée autour de 22 MHz et de largeur 300 kHz en utilisant un transformateur toroïdal à ferrite. ...
Accès restreint aux membres de l'Université de Lorraine jusqu'au 2016-05-18
... From Ayrton equation (2) and the proposed equation (10) we can draw the electrical meta model ( figure 3). ...
... The signals used to test qualitatively the model are obtained from three experiments: the first is the principle of over voltage developed at the LIEN laboratory [9] in partnership with Esterline Power System. The other two experiments are described by the standard UL1699 and are performed by Dr. Martel from Siemens AG [2]. A brief description of these three tests is summarized below. ...
Differents types of arc faults can be responsible for the start of an electrical fire. Depending on the power system and the application (photovoltaic, vehicule, aircraft, residential wiring) the arc fault may involve contact or non-contact arcing with eventually semi-conductive materials in the vicinity. Other characteristics such as the gap distance or the electrode material and geometry may also strongly differ. An electrical model was developed to fit with the arc fault scenarios described in the standard for AFCI UL1699. The contact arcing copper-graphite electrodes produced by the arc generator and the non-contact arcing on carbonized track produced with the arc clearing time tester were observed and their electrical characteristics (restrike and burning voltage, time constant and stability) could be verified thanks to the electrical model with a very good agreement. A qualitative study showing the various parameters used for fitting shows that the model is applicable regardless of the arc ignition principle.
... Additionally, the load current remains unchanged or becomes lower during a series arc fault, and the over-current protections like MCBs or fuses do not trip as expected. To improve protection against arc faults, arc fault circuit interrupters (AFDDs) are available as protection devices [36]. However, their use is still restricted to some countries. ...
... . Dalam realitanya, busur api sering kali tidak dapat terdeteksi oleh alat pengaman hal ini dikarenakan hubung singkat berlangsung sangat cepat [7]. Busur api yang tidak dapat di deteksi oleh alat pengaman ini berpotensi menimbulkan halhal yang tidak diinginkan seperti kerusakan pada alat dan timbulnya percikan api karena hubung singkat yang akhirnya bisa menimbulkan kebakaran [8]. ...
Arc faults are a fire-safety risk in both AC (alternating current) and DC wiring, but reliable detection of arc faults and determining the appropriate response is particularly difficult in DC plug-load circuits. This study will discuss the impact of impedance on arc interference characteristics in DC low voltage systems. Experiments were conducted involving accidents that increasingly occur using the arc chamber as a means of experimenting with independent variables including cable cross-sectional area and the number of fibers and control variables will consist of currents and voltages using devices using a Picoscope. In the analysis obtained values of the conductor resistance affect the characteristics of electric arcs. The smaller the value of the conductor resistance, the greater the value of the arc current produced. This is consistent with the values obtained from the study, when the smallest conductor resistance of 0.036 Ω obtained the highest value at the current value and electric arc power of 20.57 A and 19.43 W at the cross section of the conductor 1.5 mm2 with 24 fibers.
... Jika arus melebihi arus nominal/kerja, waktu pemutusan ditentukan oleh besarnya arus yang mengalir semakin [5]. Pada instalasi listrik tegangan rendah, pengaman sekring/lebur adalah suatu alat listrik yang merespon arus lebih dari sistem/perangkat terproteksi dengan sistem kerja sekering yang dapat memutus (memadamkan) arus lebih dan tahan terhadap perubahan tegangan balik (tegangan transien) [6]. Pemulihan yang timbul dari pemutusan tersebut. ...
One of the most important and expensive power lines in the distribution method is the low line voltage. In case of overload or short circuit current, it protects the electrical installation. MCB is an important component in electrical installations. The formation of sparks due to a short circuit can eventually cause a fire which has the potential to cause a fire, which is an unwanted MCB nuisance. This MCB can be used as a direct current breaker with a load, either manually or automatically. When the MCB is switched from "ON" to "OFF", the mechanical part in the MCB cuts off the electric current. The manual method involves turning off the toggle switch in front of the MCB (usually blue or black). The finished tool is then tested to see how well components such as AC MCB, DC MCB, Volt meter, LED lamps, Outlets, and lamp fittings perform. The function of the analysis of the characteristics of the use of DC MCBs for the use of DC loads works to compare the use of DC MCBs on AC loads and which ones are the most effective and the circuit is given a load until the MCB trips and amperes and volts are measured in the circuit.
... The detection of the arc is not a trivial task, being related to the path of the arc fault current. Based on this criterion, the arc fault may be classified as serial arc fault and parallel arc fault, as shown in Fig. 2 [9]. Based on Fig. 2, it is possible to see that the serial-type arc current tends to be lower than that of the parallel arc, as it is limited to the charging current. ...
... Arc fault is one of such serious threats, which is prone to cause electric fire hazard due to the partial high temperature (approximately 5000 o C or above) of the arc [1] [2]. Unfortunately, traditional protection devices such as fuses, molded case breakers, and residual current devices are not suitable for detecting arc faults [3]. To close the safety gap, arc fault circuit interrupter (AFCI) is required and mandatory in residential electrical installations since 2002 in the US [4] [5]. ...
AC series arc is dangerous and can cause serious electric fire hazards and property damage. This paper proposed a Convolutional Neural Network (CNN) based arc detection model named ArcNet. The database of this research is collected from 8 different types of loads according to IEC62606 standard. The two most common types of arcs, including arcs from a loose connection of cables and those caused by the failure of the insulation, are generated in testing and included in the database. Using the database of raw current, experimental results indicate ArcNet can achieve a maximum of 99.47\% arc detection accuracy at 10 kHz sampling rate. Even with a reduced sampling frequency of 1 kHz, our ArcNet achieved reasonably good performance. The model is also implemented in Raspberry Pi 3B for classification accuracy. A trade-off study between the arc detection accuracy and model runtime has been conducted. The proposed ArcNet obtained an average runtime of 31ms/sample of 1 cycle at 10 kHz sampling rate, which proves the feasibility of practical hardware deployment for real-time processing.
... -In [5], for arc current values of 0.5-1.5A a mean arc voltage of 56.2V has been observed. Thus, an expected minimum PARC of 45W would be consistent with these results. ...
Arc Fault Detection Devices (AFDD's) or Arc Fault Circuit Interrupters (AFCI's) are mandatory electrical protection devices in panel boards all over the world, to mitigate the risk of fire due to hazardous electrical arc faults. By its nature, the arc fault is an erratic phenomenon, with variable temporal persistency and variable ability to ignite a fire. The two main standards for AFDD certification are UL1699 & IEC62606, which require similar arcing tests. However, there is no current requirement for a minimal arcing persistency during a standard series arc test, neither a clear guideline on how to measure the arcing temporal persistency and confirm the test yielded a successful series arc fault. This work aims to enhance the standards, by proposing a simple method to precisely determine the arcing persistency during a series arc fault test. Using only the arc current and arc voltage as inputs, a standard series arc signal can be accepted or rejected, based on the measured level of temporal arcing persistency.
... In [3], explained that wavelet transformation is divided into 2 types, namely continuous wavelet transformation and discrete wavelet transform. With a function f (t) in continuous wavelet transforms it produces many coefficients. ...
... The presence of damaged (or peeled) insulation of cable is the cause of the mechanism. The main problem of arc flash is its existence that cannot be detected precisely by commercial protection devices in low voltage system DOI: 10.24507/ijicic.14.04.1389 1390 D. A. ASFANI, A. F. ILMAN, N. W. A. SANJAYA ET AL. [2][3][4][5][6], such as miniature circuit breaker (MCB) and fuse. The uniqueness of arc flash in the form of a high current in short duration can explain this problem. ...
This paper dealt with a dynamic modelling of arc flash phenomenon in low voltage installation system based on artificial neural network (ANN). There were two ANN models employed to this proposed model. The first one is dynamic resistance model and the second one is switch or short circuit contact model. The arc flash energy and the number of filaments are defined as the inputs of these ANN models, whereas the targets are the resistance value for dynamic resistance model and the switch value for switch model. The values used in modelling are obtained from experiment of arc flash initiated by phase to neutral short circuit. This fault location is parallel with the resistive load. The feed-forward back-propagation is selected as an algorithm of ANN. The result shows that the proposed model presented the level of accuracy up to 96.7%. In addition, the simulated model revealed that the lower cable impedance is and the higher load is, the greater current peak is and the shorter duration of arc flash is.
... Umumnya kebakaran terjadi di pemukiman padat penduduk yang rentan terjadi korsleting listrik (hubung singkat listrik) karena instalasi listrik yang cenderung tertata tidak rapi dan kemungkinan terjadi hubung singkat sangat tinggi.Nilai arus yang besar ketika terjadi busur api listrik ternyata tidak bisa membuat perangkat pengaman listrik konvensional seperti MCB (Miniature Circuit Breaker) atau Sekering Otomatis (Automatic Fuse) pada perumahan dan pemukiman memutus rangkaian utama. Hal ini dikarenakan durasi terjadinya hubung singkat tidak cukup untuk membuat peralatan pengaman trip [5]. ...
... -ouverture ou fermeture de contacts [BCR98][E08], -sectionnement des câbles [UL08][ GMGB01], -surchauffe des câbles [JW03], -vibrations induisant des pertes de connexions [MB10][AS08]. Un disjoncteur doit détecter un défaut d'arc dans toutes ces situations. Toujours de manière pragmatique, on choisit de reproduire ces défauts dans des conditions proches de la réalité. ...
Les arcs électriques ont été à l'origine de plusieurs cas d'accidents aériens graves par incendie ou par destruction d'organes électriques fondamentaux (ex : actionneurs, panneau supérieur,...) (TWA 800 en 1996 et Vol 11 Swiss Air en 1998). Les prévenir et les détecter constituent une amélioration notable de la sécurité en aéronautique. Ainsi, bien que le problème soit connu depuis longtemps, les premiers systèmes de détection d'arcs pour l'avionique sont très récents. Dans un avion, ces défauts ont pour causes principales le vieillissement et la détérioration des câbles. Afin d'étudier et de proposer un système de détection d'arc, les trois phases d'étude suivantes ont été suivies chronologiquement dans ce travail de thèse : premièrement, la réalisation d'un banc de production et de caractérisation des grands types d'arcs électriques (AC et DC). Ce système permet de produire des arcs contrôlés en intensité et en durée selon les modes série, parallèle, DC et AC. L'amorçage des arcs est obtenu par surtension. Cette surtension est produite par commutation inductive. Deuxièmement, la recherche de modèles électriques fiables expliquant les phénomènes d'arcs. Nous proposons donc un meta modèle associant les caractéristiques de différents modèles comportementaux et impédencemétriques.Cette association permet d'améliorer significativement les performances globales de la modélisation dans les circuits. Troisièmement, l'étude et la proposition d'algorithmes de détection en vue de l'implantation sur circuit électronique suffisamment réduit pour être implanté dans un disjoncteur. La détection de la signature d'arc se rapproche d'un problème de détection d'informations fortement bruitées pour lequel peu de solutions ont été jusqu'à présent proposées car cette recherche est relativement nouvelle.Nous proposons et testons différentes méthodes de détection.
... The current signal waveform obtained when no arc is present in the circuit is designed by "Normal operation". The difficulty of the detection is due to domestic appliances because they have a current signature similar to the signature of an arcing fault [14] [15]. The current signatures sampled frequency is equal to 1 MHz, so, each current waveform is constituted of 20000 samples par period. ...
... Abbildung 2: Vorbeugbare Brände in Deutschland 2010 Ein erheblicher Teil dieser Fehlerfälle könnte durch nicht erkannte Störlichtbögen entstanden sein und hätten mit einem wirkungsvollen Schutz gegen Störlichtbögen verhindert werden können. Zahlreichende Studien haben das Gefahrpotenzial von diesen Störlichtbögen schon gezeigt [2] [3] [4] [5] [6] [7] ...
Kurzfassung Stromkreise in der Niederspannungs-Elektroinstallation werden üblicherweise mit Sicherungen, Leitungs-schutzschaltern und Fehlerstromschutzschaltern geschützt. Bei Störlichtbogenfehlern bieten diese Schutzgeräte jedoch keinen ausreichenden Schutz. Störlichtbogen-Erfassungseinrichtungen (AFDD: Arc Fault Detection Device) sind schon in Nord-Amerika verfügbar und eine Einführung dieser Technologie auf den IEC-Märkten ist vorgesehen. Eine bekannte Funktion des AFDDs ist die Erkennung und Abschaltung von Störlichtbögen zwischen zwei Leitern, den sogenannten parallelen Störlichtbögen. Bei diesen Fehlern überquert der Strom die Trennstelle in Form eines Lichtbogens, der einen signifikanten Anteil der Leistung des Fehlers aufweist und Temperaturen weit über 5000K erreichen kann. Die zusätzliche Impedanz des Lichtbogens kann den Strom erheblich begrenzen und folglich dazu führen, dass der maximale Nennstrom des vorgelagerten Schutzorgans nicht erreicht wird und das Schutzorgan nicht auslöst. Versuche wurden durchgeführt, um die Worst-Case Bedingungen zu ermitteln. Diese sind vorhanden, wenn die Netzspannung besonders niedrig ist und die Impedanzen der Leitungen und des Störlichtbogens sehr hoch sind. Da nicht sichergestellt werden kann, dass der Lichtbogenstrom oberhalb des magnetischen Auslösestroms des Leitungsschutzschalters liegt, wurden als Weiterentwicklung der von Siemens entwickelten Schutztechnologie für serielle Störlichtbögen Algorithmen entwickelt, um auch parallele Störlichtbögen zuverlässig zu detektieren und abzuschalten.
Electrical networks can be structured into different categories by which hazard potentials caused by arc faults are recognized and specifications for respective methods of arc fault detection are defined. Different applications for AC aerospace networks, photovoltaic and DC-24/28V systems will be introduced in more detail.
Several authors propose different methods to arc fault detection based on time or frequency characteristics. Among those, some papers present the arcing fault detection using a specific frequency band on the current or voltage. This paper presents an overview of the different frequencies bands proposed by the authors that allow the detection of an arcing fault. To compare these proposed methods, we make a frequency analysis to obtain the frequencies characteristics of arcing fault for different loads signatures (resistive, inductive and nonlinear load). The method we have developed for arcing detection are based on five criterions: Analysis of the current low frequency, the voltage high frequency, the 5th harmonic current and current and voltage magnitude variations. Hardware in the loop approach allows us to test the methods of detection. Finally, our architecture of arcing detection is implemented on Field Program Gate Array (FPGA) prototyping board.
A sizable fraction of ignitions of structures are due to electrical faults associated with wiring or with wiring devices. Surprisingly, the modes in which electrical faults progress to ignitions of structure have not been extensively studied. This paper reviews the known, published information on this topic and then points out areas where further research is needed. The focus is solely on single-phase, 120/240 V distribution systems. It is concluded that systematic research has been inordinately scarce on this topic, and that much of the research that does exists is only available in Japanese.
There has been very little published research on glowing connections, especially their mechanisms and properties. In this study, oxide conductivity, surface X-ray maps, temperature measurements, and electrical waveforms were used to identify the structure and composition of glowing connections. It is shown that a glowing connection consists of a glowing molten liquid filament, which produced the orange glow that meanders on the surface of a solid copper oxide bridge that forms between two wires. Temperature and video measurements indicate that the glowing filament is in a liquid state. With the addition of oxide bridge resistivity measurements, the saw-tooth voltage pattern, typically seen in currents below 5Arms, has been explained. Also, when the glowing connection was slowly cooled, an impression of the glowing filament remained on the solid oxide. Subsequent SEM and X-ray mappings of this glow track revealed a track rich in copper, oxygen, and sulfur. This glow track explains the occasional low resistance path across the wires that can occur when the solid oxide bridge remains intact after cooling. Measurements in vacuum showed that oxygen was necessary to sustain the glowing filament even if there was a preexisting CuO oxide bridge present. Physical parameters affecting glow characteristics will be discussed; especially the semi-conducting nature of the copper oxide, and a model of the glowing contact, based on this data, that show some of the significant factors controlling the glow.
In the development of Arc-Fault Circuit interrupters (AFCIs), one of the most important parameters is the time that an arcing fault could persist before the device will interrupt the current flow and hopefully mitigate fire propagation. In 1996 Underwriters laboratories (UL) published a report on time/current ignition characteristics of arcs at 120 V. Despite the very limited number of tests (195), the obtained data still are used to develop trip times for 120 V rated AFCIs. Continuous expansion of AFCI applications from the dwelling unit bedrooms to other living areas requires knowledge of ignition characteristics at 240 V in order to specify times necessary to clear arcing faults with 240 V AFCIs. This work presents results of research on ignition characteristics of cotton fire indicators caused by electrical arcs with currents ranging from 2 A to 45 A and times from 10 s to 20 ms, when supplied by a 240 V circuit. The total number of tests exceeded 6,000 and provides a statistically acceptable confidence level. The paper examines the role of statistical analysis with respect to the ignition phenomenon due to random variations in the formation of a carbonized path. The duration of actual arcing time is compared with ignition yielding different forms of combustion. The experiments revealed that ignition is possible at currents as low as 2 A. This paper also analyzes the role of temperature rating of PVC wire insulation and other related parameters. Findings could be useful for the future development of 240 V AFCIs.
Under certain circumstances, unintentional series arcing, caused from damaged line cords and loose connections, can pose a serious fire and safety hazard. This work, focusing on residential 115 Vac applications, shows how continuous bursts of ignited gases can be created from overheated polyvinyl chloride (PVC) insulation created from glowing contacts with subsequent series arcing, or surface breakdown with subsequent series arcing. Also, surprisingly, these potentially hazardous fire conditions were created with currents as low as 0.9 Arms at 115 Vac (100 W lamp load). Little research is available about the interaction of glowing contacts, formed from loose or broken copper conductors in wiring (outlets, switches, line conductors, etc.), with electrical insulation. This work shows how glowing contacts and surface arcing can decompose PVC insulation, form ignitable gases, and that it is possible for the subsequent series arc to ignite, and burn insulation. Two conditions are identified that can create an overheated connection-a glowing contact and/or breakdown over a charred insulation surface. Mechanisms are discussed along with data for glowing contact voltage drop, photographs of glowing connections, and a gas chromatograph analysis of the evolved gases emitted from overheated PVC wiring. Selected high-speed video frames (1000 fps) taken from videos of the series arc and bursts of ignitable gasses along with synchronized current and voltage waveforms over a current range of 0.9 Arms to 5 Arms are presented. These findings are useful for advancing the state-of-the-art in fire protection by providing a better understanding of how electrical fires can initiate.
Today, roughly 20 % to 30 % of all annual residential fire hazards can be attributed to electrical faults. A variety of arc faults are considered to be the major initiator of electrical incidents. A new type of circuit protection to also address arc faults besides the faults causing overload and short circuit currents has entered the market as well as the National Electric Code® in the US in 2008: the combination-type Arc Fault Circuit Interrupter (AFCI). There are more than 35 million AFCIs installed in North American homes today. Recently, a working group under the International Electrotechnical Commission (IEC) began to actively work to develop a standard for an Arc Fault Detection Device (AFDD) for the IEC market. In this paper, the US and European based team of authors address this topic by reviewing selected elements of the American UL 1699 standard, discuss the impact of different power systems (120 V, 240 V/60 Hz, 230 V/50 Hz) and wiring practices on arc faults, and their potential consequences as well as means for mitigation.
A comparison of the two system voltages, nominally 120 Vrms and 240 Vrms at 60 Hz, typical of North American residential applications, was made to determine why a series arcing fault in SPT-2 wire at a 240 Vrms had a significantly higher probability of fire ignition than at 120Vrms even though the arc voltages were similar for both system voltages. Experiments using SPT-2 wire were performed per UL1699 standards at each voltage level with equal nominal steady-state non-arcing load currents (e.g. 5 Arms, 10 Arms, 15 Arms, 20 Arms and 30 Arms)- It was shown that the arc power, dissipated in the series arc, was greater at 240 Vrms than 120 Vrms due to increased arcing current. This was attributed to the arcing path resistance being a larger percentage of the total circuit resistance, reducing arcing current at 120 Vrms , and also to an increase in the number of arcing half-cycles at 240 Vrms because the higher system voltage was more likely to breakdown the gap than at 120 Vrms. Both these factors combined created a higher average arcing current at 240 Vrms. Furthermore, the increased arc power would result in a hotter carbonized contact gap - further reducing the breakdown strength of the gap. The average arc voltage however remained about equal for both voltage levels. These results may be useful for exploring additions to the UL1699 "fire curve" for 240 Vrms applications.
Hannover, Universiẗat, Diss., 1999. Computerdatei im Fernzugriff.
Arc waveform characteristics can be evaluated with various methods to recognize the presence of hazardous arc fault conditions. Discussion covers the arc phenomena and how it is generated in a low voltage electrical distribution circuit, as well as the isolation of the presence of hazardous conditions versus conditions that could falsely mimic the presence of an arc fault. Many waveform characteristics and conditions support the detection of hazardous arc faults and foster a more robust design, capable of withstanding unwanted tripping conditions.
In electrical power systems bolted short-circuits are rare and the fault usually involves arcing and burning; mostly the limit value of minimum short-circuit depends on arcing-fault. In AC low voltage systems, the paper examines the arcing-fault branch circuits as weak points. Different protection measures are available against the arc-faults. A first measure that can guarantee a probabilistic protection is allowed by the adoption of overcurrent protective devices (OCPD), optimizing the design of the structure of the system and/or the coordination of protection. A well known complete protection is allowed by adopting arc-fault circuit interrupters (AFCI) for the protection of branch circuits. The authors suggest a new complete protection allowed wiring of the branch circuits, particularly including extension cords, with special power cables, protected by ordinary ground fault protective devices (GFPD). The suggested design for single-core or multi-core power cables is that each insulated core has a concentric conductor shield. Converting the line-to-line fault into a line to ground fault or into a mixed type is the goal of this special cable type faults ground-forced cable (FGFC).
More about AFCIs" Schneider elect
- Gregory
Gregory, "More about AFCIs" Schneider elect., IEEE 2004
How do electrical wiring faults lead to structure ignitions?
- V Babraukas
V. Babraukas "How do electrical wiring faults lead to structure ignitions?", Fire science and technology Inc., Fire
and materials 2001 Conf. London 2001
[17] "Investigations on Branch/Feeder AFCI", Cutler-Hammer, File E45310, May 31st 2001
Elektrische Brandursachen -Erfolgversprechende Ansätze zur Schadenverhütung
- Streitberg A Von
A von Streitberg "Elektrische Brandursachen -Erfolgversprechende Ansätze zur Schadenverhütung", Allianz report
6-98, 1998