Modelling AC Arcs developing along electrolytic surfaces simulating practical polluted insulator using an original laboratory model.Abstract The present paper comprises an experimental investigation into the prediction of the critical flashover flash·o·ver n. 1. An unintended electric arc, as between two pieces of apparatus. 2. The temperature point at which the heat in an area or region is high enough to ignite all flammable material simultaneously. voltage of polluted pol·lute tr.v. pol·lut·ed, pol·lut·ing, pol·lutes 1. To make unfit for or harmful to living things, especially by the addition of waste matter. See Synonyms at contaminate. 2. insulators energized with AC voltage using a multi-channel photo-multiplier (MCP (1) See Microsoft certification. (2) (MultiChip Package) A chip package that contains two or more chips. It is essentially a multichip module (MCM) that uses a laminated, printed-circuit-board-like substrate (MCM-L) rather than ceramic (MCM-C). ) and high speed camera to observe the behavior of ac arc on electrolytic e·lec·tro·lyt·ic adj. 1. Of or relating to electrolysis. 2. Produced by electrolysis. 3. Of or relating to electrolytes. e·lec surface. In order to maintain an arc burning on a dielectric dielectric (dī'ĭlĕk`trĭk), material that does not conduct electricity readily, i.e., an insulator (see insulation). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not surface, the present work proposes a regression model for expressing analytically the experimental curves which is based on re-ignition conditions as important factor in determining the flashover criterion of a polluted insulator insulator Substance that blocks or retards the flow of electric current or heat. An insulator is a poor conductor because it has a high resistance to such flow. Electrical insulators are commonly used to hold conductors in place, separating them from one another and from under AC voltage and, also the E-I E-I Engineering and/or Installation characteristics of the ac arcs. The effects of the length of the arc discharge on its own characteristics, as well as on the cumulate voltage drops at the electrodes. It was found that the arc may propagate prop·a·gate v. 1. To cause an organism to multiply or breed. 2. To breed offspring. 3. To transmit characteristics from one generation to another. 4. with a relatively low constant velocity before the critical length is reached, and then accelerate with discontinuities at much higher velocity. This observation and the dispersion of the calculated values found for the discharge constants could mean that the arc burns in different atmosphere for any arc length Determining the length of an irregular arc segment—also called rectification of a curve—was historically difficult. Although many methods were used for specific curves, the advent of calculus led to a general formula that provides closed-form solutions in some cases. . Moreover comparison of computed results with the results obtained from other models, as well as experiments indicates a good agreement. Keywords: Polluted insulator; Arc re-ignition condition; Electrolytic surface; Multi-Channel photo-multiplier. Introduction Pollution performance of HV insulators will be the guiding factor in the design and the operation of the insulating devices in UHV UHV Ultra High Vacuum UHV University of Houston-Victoria (Texas) UHV Ultra-High Voltage UHV Upper Huallaga Valley (drug trafficking area in Peru) UHV Ultra High Viscosity transmission lines and outdoor equipment. The study of flashover process very important for electric power supply reliability, efficiency and serviceability (system) serviceability - The ease with which corrective maintenance or preventative maintenance can be performed on a system (e.g. by a hardware service technician). Higher serviceability improves availability and reduces service cost. Serviceability is one component of RAS. . The electric flashover phenomenon is dependent on different parameters such as proximity to the source of the pollution, level of contamination, surrounding weather conditions and also the nature of voltage waveforms. The presence of pollution on the surface of high voltage The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements. High voltage is used in electrical power distribution, in cathode ray tubes, to generate X-rays and particle beams, to insulators causes a flashover resulting to power system outages. It is generally recognized that the main events leading to flashover of polluted insulators under service voltage are the formation of a conductive conductive having the quality of readily conducting electric current. conductive flooring flooring or floor covering made specially conductive to electrical current, usually by the inclusion of copper wiring that is earthed layer on the insulator surface, leakage current surging with associated dry band formation and partial arc development and arc propagation along the insulator surface eventually spanning the whole insulator. This complex problem has motivated an important number of studies including field observation, laboratory investigation of the pollution surface, measurement of critical flashover voltage on polluted insulating surface and finally mathematical modeling and fundamental studies of arc propagation on polluted surface [1-8]. Generally, the flashover process on polluted surfaces is developed in two stages first pre-flashover, violet arcs appear across the air gaps, i.e. across the electrolytic surface, then one of the arcs propagates along the electrolytic surface forming a white arc, finally the white arc reaches a critical length , associated at the existence of streamers Streamers is a play by David Rabe. The last in his Vietnam War trilogy that began with The Basic Training of Pavlo Hummel and Sticks and Bones , flashover occurs suddenly. Fig.1 shows the flashover process across the liquid in the test model. During the course of the flashover tests, a high-speed frame camera was used to record the flashover process. The discharge elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. , gives out some weaker subsidiary branches of luminous intensity Luminous intensity The solid angular luminous flux density in a given direction from a light source. It may be considered as the luminous flux on a small surface normal to the given direction, divided by the solid angle (in steradians) which the surface , developing from its tip that has been observed by M. Ishi and Kawamura [9]. These observations match up and shore up the model developed by Cheng and Nour [10]. In their mathematical modeling several discharges of different lengths lying down in parallel between them and above the electrolyte electrolyte (ĭlĕk`trəlīt'), electrical conductor in which current is carried by ions rather than by free electrons (as in a metal). . Most of this researchers have been used the general form of the Ayrton arc voltage--gradient equation, although this equation is strictly valid only for high current static arcs. However Gopal and Rao [8] have proposed a model especially applicable to nonstationary low current arcs. Moreover, the phenomenon of polluted flashover becomes complex under AC voltage due to the re-ignition process. Most of these models are limited to the static state under DC voltage. Therefore, they cannot be considered as a complete model that can predict the entire temporal evolution of the electric flashover. This paper presents some electrical results obtained on an experimental set up modeling the arc discharge on polluted surfaces simulating a practical insulator. Using a laboratory model we assessed a few important features of AC flashover as well as those descended different channels of the tube multi-channel photomultiplier photomultiplier: see photoelectric cell. (MCP) are stored for processing in a PC computer through a high speed, high performance in data acquisition system DAS. These results can be used to improve a new mathematical model for predicting the flashover voltage of polluted insulators. [FIGURE 1 OMITTED] Experimental Procedure The test model is shown in figure 2 presents flat plate model, made of PMMA PMMA polymethyl methacrylate. has a constant depth 0.3cm and with a constant width 4cm and length 10cm simulating a practical insulator in which the discharge is struck between the high voltage electrode and the electrolytic surface. The high voltage electrode is placed above the electrolytic surface at distance being able to attain 1cm. In our experimental test this gap is adjusted to be 3mm. The resistivity resistivity Electrical resistance of a conductor of unit cross-sectional area and unit length. The resistivity of a conductor depends on its composition and its temperature. of the liquid is adjusted by addition of sodium chloride sodium chloride, NaCl, common salt. Properties Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals. between 2 and 10 k[OMEGA]/cm. The voltage is applied from a 60 kVA, 30 kV testing transformer over the spark gap Spark gap The region between two electrodes in which a disruptive electrical spark may take place. The gap should be taken to mean the electrodes as well as the intervening space. Such devices may have many uses. . The voltage is raised to a given level and then applied on the electrolyte by breakdown of the spark gap. If the flashover does not occur at this level of voltage then the voltage is further increased until the occurrence of flashover. For each application of the voltage, the electrolyte was changed. With the flashover observation cell, the H.V. supply to the discharge and the sensors for electrical quantities are, with some modifications, common for the two types of optical measurements carried out. The electronic camera THOMSON CSF--TSN 503 permits the visualisation of fast and luminous phenomena. There are two advantages associated with it: --A shutter grid placed near the photo-cathode at a lower potential prohibits the electron passage towards the back of the tube when the camera does not sweep; this eliminates all the background noise. --The coupling between the output screen and the photographic films Fujifilm [1] [2] Velvia 50
synchronisation, synchronization, synchronizing readjustment, adjustment, registration - the act of adjusting something to match a standard signal to the oscilloscope oscilloscope (əsĭl`əskōp'), electronic device used to produce visual displays corresponding to electrical signals. Displays of such nonelectrical phenomena as the variations of a sound's intensity can be made if the phenomena are which records the current in the discharge. In order to follow the evolution from one period to the other, the ignition was spontaneous and the recordings were guided by the signals emitted by the photo-multiplier. [FIGURE 2 OMITTED] A data acquisition device, described in references [11] and [12], permits more sensitive measurements than the camera of the emitted light intensity all along the channel and helps link them, in a reliable manner by making cyclic measurements at voltage tapping pins associated with light observation points. The tapping pins, under the channel can serve to measure the potential evolution all along its course. At a right angle to the channel, in the position of each of these tapping pins, is placed an optical fibre which targets the electrolytic surface tangentially tan·gen·tial also tan·gen·tal adj. 1. Of, relating to, or moving along or in the direction of a tangent. 2. Merely touching or slightly connected. 3. and permits to follow the variation of the emitted light. The different optical fibres are connected to a 64-channel photo-multiplier tube, Philips X81722A. This set is enclosed in a black-painted enclosure in order to limit the stray light. It is energised by a high voltage supply, Brandebourg 2479 N and protected from the intense post-flashover light by a controllable inhibition module EA Protect. The software for the exploitation of measurements permits us apart from others to represent on the same graph, the position, with respect to the applied voltage wave, of the optical signal readings. Results and Discussions The photographing films under two different angles with their axes perpendicular to the direction of discharge propagation gave us access to their cross-sectional dimensions. In these films the discharge presents similar ellipsoidal shape which connects to a vertical cylinder at the high voltage electrode side and opens out at the other side by flattening out on the liquid surface. The high speed camera also made it possible to record simultaneously the voltage and corresponding leakage current. Fig.3 shows two types of recording films streak and frame photographs. We can distinguish two zones corresponding to different light intensities in all photographs. The zone 1, closest to the high voltage electrode, is the most brilliant; its diameter corresponds to a current density [13-14]. Fig. 4 presents a typical variation of the length arc as function of time attained by the extremity of each of these two zones. The position attained by the extremity of each of these two zones as a function of time. This graph is significant for the entire set of observations: at the beginning of flashover, the zone 2 advances faster than the zone 1 and becomes more important. The transition between these two zones is especially observed near the grounded electrode. The phenomenon is reversed thereafter: the zone 1 accelerates more and absorbs the zone 2. It may observe that the arc propagation process is completed in two stages. In the first stage, the arc extended relatively slowly but in the second stage, the arc velocity increases suddenly to a relatively large value until flashover is complete. In order to observe the extension of the discharge and to put in evidence the mechanisms that explain its propagation. [ILLUSTRATIONS OMITTED] [FIGURE 3 OMITTED] [FIGURE 4 OMITTED] The results shown in the literature were most of the time acquired either by optical devices, or by electrical measurement, they don't always lead to coherent findings. That's why we have exploited both optical and electrical measurements Electrical measurements Measurements of the many quantities by which the behavior of electricity is characterized. Measurements of electrical quantities extend over a wide dynamic range and frequencies ranging from 0 to 1012 Hz. in a synchronous way obtained by MCP. Fig.5 shows that at the instant where the current I3 is maximal, light detected by the fiber f4, placed at 4cm of the high voltage electrode is more important than the light detected by the fiber f3, placed at 5cm of the high voltage electrode. It may be observed that at the instant where the 13 current is maximal the fibber fib n. An insignificant or childish lie. intr.v. fibbed, fib·bing, fibs To tell a fib. See Synonyms at lie2. f4 detects a light given out by the column of the discharge, whereas the fiber f3 didn't see the tip of the discharge. However it detected a source of light of weak intensity. This situation is similar with the other fibers. From the results taken from D.A.S. presented in Fig 6, it was noted that the typical waveforms of applied voltage, the measuring potential in the electrolyte at position x of tapping pin, and leakage current determined in a dynamic characterizing test. In each cycle, as applied voltage [V.sub.t] increased the voltage on the electrolyte increased as well. When applied voltage reached a certain value the air gap breakdown occurred and measuring voltage in electrolyte [V.sub.p] increased gradually. When the arc reached the point [P.sub.2], the measuring potential in the electrolyte at position x dropped suddenly. Due to the descending V-I arc characteristics, the lowest voltage value in electrolyte appeared near the current peak value. Therefore, it is easy to distinguish the moment when the arc reached the corresponding voltage; this corresponds to the voltage across the arc [15-17]. The simplified equivalent circuit of Fig. 7 is associated with the laboratory model. From the electrical equivalent circuit, the voltage equation may be written as: [V.sub.t] = [V.sub.arc] + [V.sub.P] (1) Where [V.sub.t] is the applied voltage, [V.sub.arc] is the arc voltage and [V.sub.P] is the voltage drop in the wet pollution layer. [FIGURE 5 OMITTED] [FIGURE 6 OMITTED] [FIGURE 7 OMITTED] [V.sub.P] = (L - x) x [R.sub.P] x [I.sub.m]. (2) For different tests, made from resistance per unit length of pollution [R.sub.p] with various values 5k[OMEGA] /cm and 9.5k[OMEGA]/cm the peak values of leakage current [I.sub.m] are measured together with the corresponding voltage drop across the arc [V.sub.arc]. The results corresponding to arc characteristics are represented in Fig. 8. [FIGURE 8 OMITTED] It seems that for each value of the length arc x less than 4cm, there is a horizontal asymptote asymptote In mathematics, a line or curve that acts as the limit of another line or curve. For example, a descending curve that approaches but does not reach the horizontal axis is said to be asymptotic to that axis, which is the asymptote of the curve. the ordinate ordinate: see Cartesian coordinates. (mathematics) ordinate - The y-coordinate on an (x,y) graph; the output of a function plotted against its input. x is the "abscissa". See Cartesian coordinates. of which we note [E.sub.0]. So the test data given in Fig.8 for expressing analytically this experimental curves. The arc constants A and n can be obtained by using regression for each value of the arc length x. [E.sub.arc] = A . [I.sub.m.sup.-n] + [E.sub.0] (3) Where [E.sub.arc] is the voltage gradient of the arc and [U.sub.E] is the cumulate value of the anode anode (ăn`ōd), electrode through which current enters an electric device. In electrolysis, it is the positive electrode in the electrolytic cell. anode Terminal or electrode from which electrons leave a system. and cathode potential drops of the arc represent the product x.[E.sub.0]. The results obtained in Table 1 indicates there is a good agreement between the values of the sum of anode and cathode voltage drops computed and those obtained from early different researchers. The cumulate value of the anode and cathode potential drops of the arc varies between 800 and 900 V only, for the range of arcs currents encountered in the pollution flashover of practical insulators, as an example, we found for [U.sub.E] the values: 900 V with positive polarity (1) The direction of charged particles, which may determine the binary status of a bit. (2) In micrographics, the change in the light to dark relationship of an image when copies are made. and 400 V between a HVDC HVDC High Voltage Direct Current metallic electrode and an iced surface [18] and the existence of anode and cathode voltages of roughly 225 and 725 V for water electrodes [19]. The arc voltage is expressed as follows: [V.sub.arc] = x. [E.sub.arc] + [U.sub.E] (4) The E-I characteristics of the arcs measuring 5cm and 6cm as function of current peak value ([I.sub.m]) can be approximated by following equation [E.sub.arc] =197 .418 .[I.sup.-0.593.sub.m] (5) However as the arc length is increases, the constants A and the index n tend toward saturation values. When the length of the arc is greater then 4cm (Fig. 9). It may be mentioned that the critical value of arc length x, is influenced by the choice of the values for the constants A and the index n. The arc constants A and n for arc modeling on the electrolytic surface obtained by using regression model on test results are compared with different values obtained in previous works Table 2. Most of the works on pollution of HV insulators have used constant values of A and n for different atmosphere, assuming the arc glide through either steam or water vapour. Aston [2] proposed A = 530 and n = 0.24 can yield good results for most problems. Farzaneh [20] recommended a combination A = 204.7 and n = 0.5607 on the ice surface. Ghosh and Chatterjee [21] have been found that the optimal combination of A and n dependent on the chemical nature of the pollutants pollutants see environmental pollution. . But there is still no consensus as to what values of arc constants A and the index n should be used in case of different polluted atmosphere. In the present work, regression models have been carried out, with the help of experimentally obtained results and the general form of the Ayrton arc voltage-gradient equation used in analysis of the low-current nonstatic arcs encountered in flashover phenomena. [FIGURE 9 OMITTED] Discussion on Figures 4 and 5 reveals that a variation in the arc length has a significant effect on arc constants. The length of arc less than 4cm has an obvious on the E-I characteristics ; higher is the water vapour concentration in the atmosphere higher is the value of A and lower is the value of n ; where as when the discharge length x is greater then 4cm , the constants A and the index n tend toward saturation values, which can represent the voltage drops on the electrodes and vary with experimental condition ; higher is the value of n and lower is the value of A . The dispersion of the values found for A and the index n could mean that the discharge burns in different atmosphere for different length arc x. As shown in Fig. 10, during a half -wave of alternating re-ignitions, the flashover voltage (called the re-ignition voltage) decreases with the increase of the instantaneous current from zero and reaches a value (the arc voltage) corresponding to the peak value of the current [FIGURE 10 OMITTED] The arc voltage increases with the decrease of the current from the peak value and finally, the arc discharge extinguishes. We note that the re-ignition voltage increases at the negative alternation alternation /al·ter·na·tion/ (awl?ter-na´shun) the regular succession of two opposing or different events in turn. alternation of generations metagenesis. due the fact that the positive discharge can be ignited easily through the intermediary positive streamers because their critical field of propagation value is in the average of 5 kV/ cm However this value is three times increased in the case of negative streamers. The voltage across the partial arc and the corresponding current can be obtained by analyzing the representative waveforms recorded by data acquirement system (DAS). Under AC conditions, in order to maintain an arc burning on a dielectric surface, not only Equation 1 but also the arc re-ignition conditions must satisfied, the arc reignition conditions can be expressed by: [V.sub.m][greater than or equal to] kv/[I.sup.b.sub.m] (6) Where k and b are re-ignition constants. Therefore the critical re-ignition condition is: [I.sub.m] = [(k.x/[V.sub.m]).sup.1/b] (7) This equations signifies that under critical condition, when the peak value of applied voltage is [V.sub.m] and peak value of the leakage current is [I.sub.m], the length of arc can reach x cm . In order to determine the re-ignition conditions k and b a series of tests were carried out and the [V.sub.m] and [I.sub.m] for given value of arc length x were measured. The results of these tests are presented in Fig. 11. Most of the works on pollution of HVAC (Heating Ventilation Air Conditioning) In the home or small office with a handful of computers, HVAC is more for human comfort than the machines. In large datacenters, a humidity-free room with a steady, cool temperature is essential for the trouble-free insulators have used constant values of k and b for different author. Calverie and porcheron [22] proposed using a practical insulator combination of k = 800 and b = 0.50. By analysing the results with the help of non linear regression Linear regression A statistical technique for fitting a straight line to a set of data points. method k and b are determined as: [FIGURE 11 OMITTED] k = 762.684 and b = 0.533 The results obtained by the laboratory model indicate there is a good agreement between the computed values of the re-ignition constants those obtained from Claverie and porcheron. This means under NaCl contamination, the re-ignition and the arc voltages are influenced by the Na ions in discharge space and arc column. A discussion of the two characteristics will greatly assist at understanding of the flashover mechanism on contaminated contaminated, v 1. made radioactive by the addition of small quantities of radioactive material. 2. made contaminated by adding infective or radiographic materials. 3. an infective surface or object. insulator surfaces. When Equations 6 and 7 are satisfied simultaneously; the arc on electrolytic surface can be developed and maintained. [V.sub.m] = Ax. [(kx/[V.sub.m]).sup.-n/b] + [R.sub.p] (L - x). [(kx/[V.sub.m]).sup.1/b] + [V.sub.E] (8) Equation 8 presents a relationship between the peak value of applied voltage [V.sub.m] and the length of arc x, when the constants A and n are determined. In order to validate the mathematical model calculated and experiment results of flashover voltage are plotted in Fig12. Because the development of the arc discharge is not continuous phenomenon, it's difficult to find the values of A and n that leads to offer a comprehensive investigation of the chemical parameter under their control, the salt concentration and therefore the resistivity of the liquid they are discharging across. However to calculate the flashover voltage the choice of this values is important [21]. [FIGURE 12 OMITTED] Conclusions The flashover phenomena on a polluted insulator surface to which a 50Hz high alternating voltage is applied have been investigated. In this study, the fundamental behaviour of partial arcs on NaCl electrolytic surface under AC voltage was investigated with the aid of high--speed frame camera and M.C.P in order to predict the flashover voltage of polluted insulators. The results obtained are summarized as follows: --the light emission from the tip of the partial discharge In electrical engineering, a partial discharge (PD) is a localised dielectric breakdown of a small portion of a solid or liquid electrical insulation system under high voltage stress. is stronger than the stem ,two regions can be identified : zone I , bright and well demarcated, fits to the discharge intermediate between glow and arc used in the model ; zone II blurred and less luminous could be in connection with a space charge ejecting forward the tip of the discharge. --The arc propagation could be divided into two stages. In the first stage, the propagation velocity is relatively small, while in the second stage, the arc propagation velocity increases suddenly until flashover occurs. --A regression model based on the Ayrton static arc voltage-gradient equation was developed to determine the arc constants A and the index n with the help of some electrical results taken from an original set up permitting to predict the flashover voltage on polluted insulators. The proposed modeling takes into account the effect of change in the lengthening lengthening (lengkˑ·the·ning), n the use of various massage or muscle energy techniques to relax and stretch muscle and connective tissue. mechanism of the discharge, due to the fact that the arc burns in different atmospheres characterising a discontinuity dis·con·ti·nu·i·ty n. pl. dis·con·ti·nu·i·ties 1. Lack of continuity, logical sequence, or cohesion. 2. A break or gap. 3. Geology A surface at which seismic wave velocities change. of its extension --The re-ignition condition can be expressed as equation of the arc peak value of applied voltage and the arc length and peak value of leakage current. It was found that the re-ignition and arc voltages are greatly influenced by the behaviour of the chemical nature of the pollutants ions in discharge space and arc column. References [1] Obenaus. F., 1935, "Die Uberschlagspnnung verschmutzter isolatoren", ETZ ETZ Elektrotechnische Zeitschrift ETZ Metz/Nancy, France - Frescaty (Airport Code) ETZ Extrapolations-To-Zero ., 56, 369-370. [2] Alston. L.L, Zoledziowski. 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Paul Sabatier (August 3, 1858 - March 4, 1928), was a French clergyman and historian who produced the first modern biography of St. Francis of Assisi. , Toulouse, no 1323 [8] Gopal. S., Rao. Y.N, 1984, "Flashover phenomena of polluted insulators", IEE Proceedings, vol. 131, no4, pp. 140-143 [9] Ishii M., Kawamura T., Ohashi H. Et Matsumoto T., 1987, "Observation of DC partial arcs on contaminated surface by means of interferometric method", 5th Int. Symposium on High Voltage Engineering, Braunschweig (Germany), Paper No 51-06, pp. 1-4 [10] Cheng. T.C., Wu. Y.C., Nour. H., 1984, "DC interfacial Breakdown on contaminated electrolytic surfaces", IEEE Transaction on Electrical Insulation Electrical insulation A nonconducting material that provides electric isolation of two parts at different voltages. To accomplish this, an insulator must meet two primary requirements: it must have an electrical resistivity and a dielectric strength , vol. 19, pp. 536-542 [11] Pollentes. M., Zmajkovic. P., 1995, Proc ICSD ICSD Inorganic Crystal Structure Database ICSD International Classification of Sleep Disorders ICSD International Committee of Sports for the Deaf ICSD International Central Securities Depository 95 5th International Conference on Conduction conduction, transfer of heat or electricity through a substance, resulting from a difference in temperature between different parts of the substance, in the case of heat, or from a difference in electric potential, in the case of electricity. and Break-down in solid Dielectrics, pp 224-228. [12] Zmajkovic P., 1986, 'Modelisation du contournement electrique et validation experimentale du mecanisme propose pour l'extension de la decharge", These de Docteur de l'Universite Paul Sabatier, Toulouse. [13] Mahi D., 1986, 'dynamique de l'allongement sur une surface faiblement conductrice d'une decharge alimentee en courant Cou`rant´ a. 1. (Her.) Represented as running; - said of a beast borne in a coat of arms. n. 1. A piece of music in triple time; also, a lively dance; a coranto. 2. alternatif', These de Docteur Ingenieur, Universite Paul Sabatier, Toulouse, no957. [14] Mahi. D., Zegnini. B., 2001, "Evolution of the potential taken from A channel filled with an electrolyte submitted to an electrical discharge Noun 1. electrical discharge - a discharge of electricity discharge - the sudden giving off of energy nerve impulse, nervous impulse, neural impulse, impulse - the electrical discharge that travels along a nerve fiber; "they demonstrated the transmission of energized by an alternative current and correlation with the emitted light", second ELECO 2001 proc, electric control, sponsor by IEEE, 7-11 November 2001 Bursa Bursa, city, Turkey Bursa (b  rsä`), city (1990 pop. 838,323), capital of Bursa prov., NW Turkey. , Turquie, pp. 178-182
[15] Zegnini. B., Mahi. D., Huraux C., and Chaker. A., 2001, "Electrical and optical analysis of the electric discharge, energized by AC voltage, on polluted insulating surface", proceedings ISEIM2001, sponsor by IEEJ IEEJ Institute of Electrical Engineers of Japan , 19-22 November 2001 Hemji Japan, pp. 316-319 [16] Zegnini. B., Mahi. D., 2002, "The relationship between the estimation intensity of electrical current flowing the electrolyte and the propagation of the local discharge on an electrolytic surface under AC voltage," conference record IEEE 2002 on electrical insulation ISEI ISEI International Society on Early Intervention 2002, sponsor by IEEE, April 7-10, 2002 Boston, MA, U.S.A. pp.241-244 [17] Zegnini. B., Mahi. D., 2002, " Etude dynamique de la propagation sur une surface d'electrolyte d'une decharge electrique alimentee en courant alternatif " An International Publication of Engineering Sciences /AJOT, ISSN ISSN abbr. International Standard Serial Number 1111-357X, serie B
[18] Bui.H.T., Phan. L.C, and Huraux. C, 1984, IEEE International symposium on Electr. Insul. Paper 84CH1964-6, pp. 85-88. [19] Rumeli. A, 1976, IEEE, Trans. on Electr. In sul, (11), 115. [20] Farzaneh. M and Zhan. J., 2000, IEEE Trans on Dielelectrics and Electrical Insulation, (7) 269. [21] Ghosh P.S. and Chatterjee. N., 1995, IEEE Trans on Dielelectrics and Electrical Insulation, (2)128. [22] Claverie. P., Porcheron. Y., 1973, IEEE Trans. on Pas 92, 1121 [23] Verma MY, 1983, ETZ Archives. [24] Guan guan: see curassow. Z., Zhang. R., 1990, IEEE, Trans.on Electr. Insul, (25) 723. [25] Tapalis. F.L, Leontide N., and Stathopulos I.A, 1992, Proc Int Conf on Gas Discharge Gas discharge A system made up of a gas, electrodes, and an enclosing wall in which an electric current is carried by charged particles in response to an electric field, the gradient of the electric potential, or the voltage between two surfaces. and appl. [26] Farag. A.S and Cheng. T.C, 1997, IEEE Elec Insul Conf. [27] Holtzhausen. J.P, 2001, Proc of LASTED Int Conf Power and Energy Syst [28] Gonos I.F., Topalis. F.V. and Stathopolos. La., 2002, IEE Proc. Gener. Transm. Distrih., (149) 373. Boubakeur Zegnini (a,b,)* , Djillali Mahia, Juan Martinez-Vega (b) Abdelkader Chaker (c) (a) Amax Telidji University of Laghouat, Materials Laboratory, Electrical Engineering electrical engineering: see engineering. electrical engineering Branch of engineering concerned with the practical applications of electricity in all its forms, including those of electronics. Department, P.O.Box37G, Ghardaia road, Laghouat 03000, Algeria (b) Universite de Paul Sabatier, LGET LGET Lieutenant Governor for Education and Training CNRS-UMR5003, 118 route de Narbonne, 31062 Toulouse, France (c) ENSET Oran, Net works laboratory, Electrical Engineering Department, Algeria * Corresponding Address: Universite de Paul Sabatier, LGET CNRS-UMR5003, 118 route de Narbonne, 31062 Toulouse, France E-mail: zegnini@lget.ups-tlse.fr
Table 1: Values of the voltage drops on the electrodes for different
arc length x.
Arc length [E.sub.0] (Volts) [U.sub.E] (Volts)
x
2cm 427.93 855.86
3cm 276.82 830.46
4cm 180.31 721.24
Table 2: AC Arc constants A and n for different authors.
Author's constants A n Ref
Obenaus (1958) 100 0.7 [1]
Alston (1963) 63 0.76 [2]
Calaverie and al (1973) 100 0.50 [22]
Rumeli (1976) 518 0.273 [19]
Rahal and Hurraux (1979) 530 0.24 [5]
Verma (1983) 53.45 0.50 [23]
Guan and Zhang (1990) 140 0.67 [24]
Tapalis and al (1992) 131.1 0.374 [25]
Ghosh and Chaterjee(1995) 360 0.59 [21]
Farag and al (1997) 530 0.24 [26]
Holtzhausen (2001) 59 0.53 [27]
Gonos and Topalis (2002) 124.8 0.409 [28]
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