Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases

The new criterion of arc stability and instability is introduced, which enables one to find arc duration dependently on given circuit parameters and properties of contact material. The mathematical model of phase transformations inside electrodes during arcing is elaborated which describes dynamics...

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Published in:Электрические контакты и электроды
Date:2010
Main Authors: Kharin, S.N., Shpady, Yu.R., Kulakhmetova, A.T.
Format: Article
Language:English
Published: Інститут проблем матеріалознавства ім. І.М. Францевича НАН України 2010
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/28894
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Cite this:Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases / S.N. Kharin, Yu.R. Shpady, A.T. Kulakhmetova // Электрические контакты и электроды. — К.: ИПМ НАН України, 2010. — С. 123-131. — Бібліогр.: 7 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Kharin, S.N.
Shpady, Yu.R.
Kulakhmetova, A.T.
author_facet Kharin, S.N.
Shpady, Yu.R.
Kulakhmetova, A.T.
citation_txt Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases / S.N. Kharin, Yu.R. Shpady, A.T. Kulakhmetova // Электрические контакты и электроды. — К.: ИПМ НАН України, 2010. — С. 123-131. — Бібліогр.: 7 назв. — англ.
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container_title Электрические контакты и электроды
description The new criterion of arc stability and instability is introduced, which enables one to find arc duration dependently on given circuit parameters and properties of contact material. The mathematical model of phase transformations inside electrodes during arcing is elaborated which describes dynamics of arc erosion in metallic and gaseous arc phases. Increasing of arc duration and erosion with inductance occurs on account of enlarging of gaseous arc phase, while variation of metallic phase is relatively small. Получен новый критерий стабилизации дуги, который позволяет найти зависимость продолжительности металлической фазы дуги от заданных параметров цепи и свойств контактного материала. Предложена математическая модель фазовых переходов внутри электродов в процессе горения дуги, которая описывает динамику дуговой эрозии в металлической и газовой фазах дуги. Установлено, что причвозрастания продолжительности дуги и эрозии контактов, происходящего с ростом индуктивности цепиявляется расширение газообразной фазы дуги относительно ее металлической фазы. Отримано новий критерій стабілізації дуги, який дозволяє знайти залежність тривалості металічної фази дуги від заданих параметрів ланцюга і властивостей контактного матеріалу. Запропоновано математичну модель фазових переходів в середині електродів в процесі горіння дуги, яка описує динаміку дугової ерозії в металічній і газовій фазах дуги. Встановлено, що причиною зростання тривалості дуги і ерозії контактів, яке має місце із зростанням індуктивності ланцюга, є розширення газоподібної фази дуги відносно її металічної фази.
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fulltext UDC 517.958:[536.2+539.219.3] Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases S. N. Kharin, Yu. R. Shpady, A. T. Kulakhmetova Institute of Mathematics of the National Academy of Sciences of Kazakhstan The new criterion of arc stability and instability is introduced, which enables one to find arc duration dependently on given circuit parameters and properties of contact material. The mathematical model of phase transformations inside electrodes during arcing is elaborated which describes dynamics of arc erosion in metallic and gaseous arc phases. Increasing of arc duration and erosion with inductance occurs on account of enlarging of gaseous arc phase, while variation of metallic phase is relatively small. Keywords: mathematical model, arc erosion, arc phases. Introduction Investigation of dynamical arc phenomena in opening electrical contacts is very important for performance build-up of circuit breakers by means of decrease of arc duration and erosion. Mayr’s and Cassie’s models [1] and their generalization [2] based on the power balance method are not applicable to describe arc temperature field at the initial arc stage just after arc ignition. Elenbaas-Heller equation gives information about radial distribution of the arc temperature however it is correct for stationary arcs only [3]. Arc dynamics should be described by transient heat equation taking into account nonlinear arc characteristic. It is the first intent of this paper. The second one is to device a method for calculation of arc erosion in dynamics. Mathematical model of arc temperature and conductivity at metallic arc phase Equation for the temperature The arc temperature θ in opening contacts just after ignition is less than the threshold value required for gas ionization, , however it is sufficient to ionize metallic vapours in the contact gap, which takes place at the temperature : ( , )r t igθ imθ θim < θ < θig. This initial stage, called metallic arc phase, has very short duration and occurs in a small contact gap. Therefore the arc takes the form of a disk, which thickness is much less than radius, and the axial temperature component can be neglected in comparison with radial component. In this case the heat equation for the arc should be written in the form 2θ 1 θ(λ ) σ rC r E t r r r W∂ ∂ ∂ = + − ∂ ∂ ∂ , (1) © S. N. Kharin, Yu. R. Shpady, A. T. Kulakhmetova, 2010 123 where C and λ are thermal capacity and density, λ and σ are heat and electrical conductivities of the arc plasma, is electrical field and is power loss due to arc radiation and heat conduction from arc column to electrodes. The initial temperature distribution along radius E rW 124 r θ( ,0) ( )r f= (2) can be found from the solution of the heat equation for metallic vapours at the pre-arcing stage [4, 5]. We can approximate the function f(r) = θoJo(μ1r / rA) by parabola 2 0 2( ) θ (1 ) A rf r r = − or by the Bessel function f(r) = θoJo(μ1r / rA) , (3) where is the first root of the Bessel function and is the temperature maximum at the centre of arc disc. 1μ 2, 405= 0θ The temperature on the interface r = rA between ambient air and arc plasma should be equal to threshold of metal ionization θ(rA, t) = θmi. (4) It should be noted that thermal and electrical plasma conductivities, and σ , depend essentially on the temperature and this dependence can not be averaged. In contrast the arc radiation can be neglected for metallic arc phase, which temperature is relatively low : < ≈ 5000 oC (fig. 1). λ rW imθ igθ Equation for electrical conductivity σ To solve the heat equation (1) we use the Kirchhoff’s substitution mi θ θ (θ) (θ) θS = ∫ λ d . (5) Then the equation (1) transforms to 21 ( ) σ λ r C S Sr E t r r r W∂ ∂ ∂ = + − ∂ ∂ ∂ . (6) Solving the equation (5) with respect to θ , get miθ θ ( )g S= + . (7) Since the function σ = σ (θ) is given (fig. 1), can write this function in term of using (6), i. e. . Linearization of this function gives the expression (fig. 2) σ σ σ ( )S= σ bS= ; g gi σ tan φb S = = , (8) where is given electrical conductivity at the transition from metallic arc phase to gaseous arc phase, when θ = θgi, and gσ mi θgi θ λ(θ) θgiS = ∫ d . (9) 5 6 7 8 9 10 0 1 2 3 4 5 6 1 2 3 3, 10T K , , rC Wλ 5 6 7 8 9 10 0 1 2 3 4 5 6 1 2 3 3, 10T K , , rC Wλ S ( )Sσ ϕ 0 gσ giS S ( )Sσ ϕ 0 gσ giS Fig. 1. Temperature dependence of λ, σ and Wr: 1 — , Wm-1 K-1; 2 — C, ·102 Jm-3 K-1; 3 — Wr, ·1011 Wm-3 [6]. λ Fig. 2. Linear approximation of . giσ( )S Substituting (8) in (7) and using notation 2; τ λ x Cr E bE b = = , (10) can write the equation with respect to σ 2 2 σ σ 1 στ t x x x ∂ ∂ ∂ σ= + + ∂ ∂ ∂ . (11) It should be noted that can be considered as constant because the thermal diffusivity is approximately constant (fig. 1). The domain for this equation is τ 2 / λa C= 00 x x< < , where 0 Ax r E b= . The boundary conditions (2)—(4) transform to the type σ( ,0) ( )x F x= (12) with mi ( / ) θ ( ) (θ) θ f x E b F x b d= ∫ λ , . (13) 0σ( , ) 0x t = The solution of the problem (11)—(13) can be found in the form of Fourier-Bessel series 2 0 0 1 σ( , ) exp[ ( 1) / τ] ( )n n n x t C k t J k ∞ = = − −∑ x , (14) where 0 02 2 0 1 0 2 ( ) ( ) (μ ) x n n n C F x J k x xdx x J = ∫ 0μ /n nk x, = , and μ are roots of the Bessel function: n 0 (μ ) 0, 1,2,3,...nJ n= = . For approximation (3) 0 0 1 0σ( ,0) σ (μ / )x J x x= and the solution (14) takes the simple form 2 1 0 02 0 μσ( , ) σ exp[ ( 1) / τ] (μ / )1 0x t t J x = − − x x , 125 Taking into account (10), we get finally the expression for arc electrical conductivity in the form 2 2 2 2 0 1 0 12σ( , ) σ exp[ (μ ) ] (μ / )A A A a tr t E br J r r r = − − . (15) The arc temperature can be found now from the expressions (5) and (8). Let us introduce the criterion of arcing 2 2 1ξ AE br 2μ= − . (16) We should distinguish three cases (fig. 3): 1) ξ . Rise of arc conductivity, power and temperature due to Joule heating. 0> 2) ξ . Maximum value of arc conductivity and power. 0= 3) ξ . Arc conductivity, power and temperature decrease, thus the arc should extinguish. 0< Interaction between arc and contact surface At the first stage of contact opening and then changes the sign. To find the critical point ξξ 0> 0= we need to know the dynamics of arc radius rA, which expands during arcing. Then using formula 2π σA IE r = (17) and the expression (16) we can find the critical time crt t= at which ξ 0= . For this purpose we consider the region DA occupied by arc interacting with contact surface (fig. 4). This interaction results into phase transformations of contact material and formation of three zones: 1. The zone of evaporated material: : 0 ( ), 0 σ ( , )b b bD r r t z r t≤ ≤ ≤ ≤ . 2. The zone of melted material: Dm : σb (r, t) ≤ z ≤ σm (r, t), if 0 ≤ r ≤ rb (t), 0 ≤ z ≤ σm (r, t), if rb (t) ≤ r ≤ rm (t). 3. The solid zone: : σ ( , ) , if 0 ( ), 0 if ( ) s m m mD r t z r r t z r t r≤ ≤ ∞ ≤ ≤ ≤ ≤ ∞ ≤ ≤ ∞ . The contact temperature can be presented as the sum ( , , )CT r z t ( , , ) ( , , ) ( , , )C J ST r z t T r z t T r z t= + , (18) where and are the temperature components due to volumetric Joule heating and due to surface arc flux heating respectively. The expression for calculating of the first component is given above. It can be shown that the Joule component is important at the pre-arcing stage only, and it can be neglected after arc ignition. The expression for the second component can be found similarly in the form . (19) ( , , )JT r z t ( , , )ST r z t ( , , )JT r z t 1 1 1 1 1 1 1 1 1 1 0 0 ( , , ) [ ( , ) ( , ) ( , )] ( , , , ) t S c b mT r z t dt P r t P r t P r t G r r z t t r dr ∞ = − − −∫ ∫ 1 Here is the total heat flux (power per unit area) entering the contact surface during arcing, ( , )cP r t ( , )bP r t and ( , )mP r t are portions of this flux consumed for 126 Fig. 3. Evolution of arc conductivity. evaporation and melting of contact material, which can be found by the expressions σ ( , )( , ) b b b r tP r t L t ∂ = ∂ γ ; σ ( , )( , ) m m m r tP r t L t ∂ = ∂ γ ; (20) 0ξ < 0ξ = 0ξ > (0, )tσ 0σ t 0ξ < 0ξ = 0ξ > (0, )tσ 0σ t σ(0, t) ξ > 0 σo ξ = 0 ξ < 0 where and are specific heat for evaporation and melting, bL mL γ is density of contact material. It reasonable to assume that the isothermal surfaces σ ( , )bz r t= and mσ ( , )z r t= are ellipsoids of revolution that can be found from the equations 2 2 2 2 1; ( ) ( )b b r z r t z t + = 2 2 2 2 1 ( ) ( )m m r z r t z t + = ; in other words 2 2σ ( , ) ( ) 1 / ( ) ;b b br t z t r r t= − 2 mσ ( , ) ( ) 1 / ( )mr t z t r r t= − 2 m . (21) The functions , , and should be found from the equations ( )br t ( )bz t ( )mr t ( )mz t C ( ( ),0, )b bT r t t T= ; T zC (0, ( ), )b bt t T= ; T r ; C ( ( ), 0, )m mt t T= mC (0, ( ), )mT z t t T= , (22) where T is the melting temperature of the contact material. m If the heat fluxes P r , obeys the normal Gauss’s radial distribution ( , )c t ( , )bP r t ( , )mP r t 2 2( , ) ( ) exp( ) ( )c c A rP r t P t r t = − ; 2 2( , ) ( ) exp( ) ( )b b A rP r t P t r t = − ; 2 2( , ) ( )exp( ) ( )m m A rP r t P t r t = − , (23) then the integral with respect to r in the formula (19) can be calculated and the expression for the contact temperature becomes more simple form 2 2 2 1 1 1 1 2 2 22 2 1 1 10 1 1 1 [ ( ) ( ) ( )] ( )( , , ) exp[ ] τ. (24) 4 ( ) ( ) 4 ( )λ π [ ( ) 4 ( )] t c b m A S AA P t P t P t r ta z rT r z t d a t t r t a t tr t a t t t t − − = − − − + −+ − −∫ t The heat flux should be calculated taking into account positive components due to arc radiation, electron (or ion) bombardment of anode (cathode) contact surface, inverse electrons from the arc column, and negative components due to power losses for evaporation, radiation, electron emission cooling and heat conduction inside the contact body. The expressions for all these components can be found in the paper [7]. However the model in considered case can be simplified because the information about current, voltage and displacement is available from experiment. Therefore it is more convenient to calculate power generated by arc W directly from the measured values of arc voltage U , arc current ( )cP t A ( )A ( )AI t and then arc heat flux entering contact is 2 ( ) ( ) ( )( ) 2π ( ) 2π ( ) A A A c A A I t U t P tP t r t r t2 ⋅ = = . (25) 127 r z0 x(t) Fixed contact Movable contact ( ) Ar t sD mD bD AD ( , )mz r tσ= ( , )bz r tσ= ( )mz t( )bz t ( )mr t ( )br t r z0 x(t) Fixed contact Movable contact ( ) Ar t sD mD bD AD ( , )mz r tσ= ( , )bz r tσ= ( )mz t( )bz t ( )mr t ( )br t Fig. 4. The arc and contacts geometry: arc region AD , evaporated , melted and solid bD mD sD zone. This expression is the final equation, which enables in the aggregate with other cited above equations to calculate dynamics of contact melting, evaporation, arc radius and arc power . ( )Ar t ( )AP t Fig. 5 and fig. 6 depict dynamics of arc power and temperature for AgCdO contacts calculated using above considered model at the conditions: supplied voltage 0 14 V,U = current inductance opening velocity [2]. One can see that critical time in this case is 0 20 A,I = 47,5 mH,L = 0,2 m / sV = cr 10 mst = , however the maximum of arc temperature occurs a little bit later, at 15 mst = due to thermal inertia. Fig. 5. Dynamics of arc power . ( )AP t Fig. 6. Arc temperature: 1 — experimental data [2]; 2 — calculation. 128 3 4 5 6 7 8 0.1 1 10 100, t ms 3, 10A KT 1 2 0 5 10 15 20 25 30 35 400 50 100 150 200 250 300 350 400 , m st ( ) , WAP t 0 t, ms ТА, ·10-3 К t, ms Transition from metallic arc phase to gaseous arc phase Temperature field and erosion The duration of metallic phase is very short, therefore the arc thickness is still small and above considered model can be applied to describe the transition from metallic to gaseous phase if we replace all parameters of metallic vapours by parameters of gaseous vapours. Dynamics of this transitions is represented in fig. 7. One can see, that at the first stage of arcing, when the contact gap does not exceed 20 μm, anode temperature rises very sharp in comparison with cathode temperature. Fig. 7. Dynamics of anode and cathode temperature at the centre of arc root. 4 129 It can be explained by the fact that in a short arc, which length is comparable with the length of ionization zone, electron temperature is much greater than ion temperature Ті, therefore kinetic energy of electrons bombarding anode, eT 3 2 e e kT j e , exceeds significantly kinetic energy of ions entering cathode, 3 2 i i kT j e . Moreover, calculation shows that in this range of contact gap electron component of current density ej is much greater than ion component ij , that is an additional reason for anode overheating and material transfer from anode to cathode. However intensive evaporation from anode and increasing of anode arc spot radius, that entails decreasing of current density, cause anode cooling and decreasing of its temperature, while cathode temperature continues to increase. The point of intersection of anode and cathode temperature occurring at corresponds to change the direction of material transfer for inverse and to beginning of compensation arc stage, which continues up to 0,15 msact = 1 1,8 mst = and transforms then into cathodic stage (fig. 8). Calculation enables to conclude that cathodic arc stage begins in metallic phase with temperature about 4700 K, that is less than threshold ionisation, however transition to gaseous phase occurs just at . Results of calculated erosion given in fig. 8 are evidence of the fact, that the main portion of erosion in inductive circuits occurs in gaseous phase. Calculated values for 1 2 mst = 0 1 2 3 3, , 10 Ka cT T ⋅ aT cT 0 0,1 0,2 0.3 , mst 0 0.4 0.5 130 g. 8. Anode and ca- : Fi thode mass transfer. From bottom to top 1, 2 — ecM (calculated and experi ent [2]); 3. 4 — ea m M (experi- ment [2] an calcu- lated). metalli d c phase are sligh y greater than experimental data. It can be explained by recycling phenomenon, d m , ati m Influence of inductance on arc duration Similar calculations were e in the range from 1 to 400 mH arc phase, while vari Fig. 9. Arc sus Conclusions Dynamics of temperature and electrical con e described and analysed satisfactorily by the es one to find arc duration dep ng arcing is elaborated which desc account of enlarging of gaseous arc pha 1. rowne T. E. Circuit Interruption, Theory and Techniques. — New York and Basel: Marcel Dekker, 1984. — , μsAt tl i. e. re-deposition of evaporate aterial which is ignored in the mathem cal odel. -30 -25 -20 -15 -10 -5 0 5 0,001 0,01 0,1 1 10 100 7, 10 gecM M −⋅ , mst ea carried out for different values of inductanc . It was found that arc duration increases proportionally inductance and depends on current at relatively small values of inductance (fig. 9). However for inductance greater than 10 mH this dependence becomes negligible. This result correlates with experimental data observed in work [2]. Increasing of arc duration with inductance occurs on account of enlarging of gaseous ation of metallic phase is relatively small. The same conclusion may be proposed for increasing of erosion. However further increasing of inductance up to a few hundred millihenry in the range of low current leads to decrease arc duration and erosion due to arc-to-glow transformation, which is considered below. duration ver inductance and current 1 — Io = = 0,6 A, 2 — Io = = 1 A and Io = = 20 A. ductivity can b model based on a non-linear problem for axisymmetric heat equation. The new criterion of arc stability and instability is introduced, which enabl endently on given circuit parameters and properties of contact material. The mathematical model of phase transformations inside electrodes duri ribes dynamics of arc erosion in metallic and gaseous arc phases. Increasing of arc duration and erosion with inductance occurs on se, while variation of metallic phase is relatively small. B 580 р. 2. Kharin S. N., Nouri H. and Davies T. Influence of Inductance on the arc evolution in AgMeO electrical contacts // Proc. of the 48th IEEE Holm conf. on Electrical Contacts. — Orlando, Florida, USA, 2002. 3. Slade P. Electrical Contacts. Principles and Applications / Marcel Dekker ed. Basel, Switzerland, 1999. 0, 1 10 100 1000 10000 100000 0,01 0,1 1 10 100, mHL 1 2 3 1 0,001 1 2 3 4 131 ntacts al stage // Proc. of 43th IEEE Holm Математическая модель температуры и электрической проводимости дуги в С. Н. Харин, Ю. Р. Шпади, А. Т. Кулахметова Получен новый критерий стабилизации дуги, который позволяет найти зависимость продолжительности иной , Механічна модель температури та електричної провідності дуги С. М. Харін, Ю. Р. Шпади, А. Т. Кулахметова римано новий критерій ст ривалості металічної фази тематична модель, дугова ерозія, дугові фази. 4. Kharin S. N., Nouri H. and Bizjak M. Effect of vapour force at the blow-open process in double-break co // IEEE Transactions on Components and Packaging Technologies. — 2009. — 32, No. 1. — P. 180—190. 5. Kharin S. N., Nouri H., Amft D. Dynamics of electrical contact floating in vacuum // Proc. of the 48th IEEE Holm conf. on Electrical Contacts. — Orlando, Florida, USA, October 21—23, 2002. 6. Engelsht W. S. Dynamics of Electrical Arc. — Ilim ed., Bishkek, 1988. 7. Kharin S. N. Mathematical model of the short arc phenomena at the initi conf. on Electrical Contacts, 1997. — Philadelphia, USA. — P. 289—305. металлической и газовой фазах металлической фазы дуги от заданных параметров цепи и свойств контактного материала. Предложена математическая модель фазовых переходов внутри электродов в процессе горения дуги, которая описывает динамику дуговой эрозии в металлической и газовой фазах дуги. Установлено, что прич возрастания продолжительности дуги и эрозии контактов, происходящего с ростом индуктивности цепи является расширение газообразной фазы дуги относительно ее металлической фазы. Ключевые слова: математическая модель, дуговая эрозия, дуговые фазы. в металічній і газовій фазах От абілізації дуги, який дозволяє знайти залежність т дуги від заданих параметрів ланцюга і властивостей контактного матеріалу. Запропоновано математичну модель фазових переходів в середині електродів в процесі горіння дуги, яка описує динаміку дугової ерозії в металічній і газовій фазах дуги. Встановлено, що причиною зростання тривалості дуги і ерозії контактів, яке має місце із зростанням індуктивності ланцюга, є розширення газоподібної фази дуги відносно її металічної фази. слова: маКлючові Fig. 6. Arc temperature: 1 — experimental data [2]; 2 — calculation.
id nasplib_isofts_kiev_ua-123456789-28894
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn XXXX-0085
language English
last_indexed 2025-11-24T09:36:00Z
publishDate 2010
publisher Інститут проблем матеріалознавства ім. І.М. Францевича НАН України
record_format dspace
spelling Kharin, S.N.
Shpady, Yu.R.
Kulakhmetova, A.T.
2011-11-25T15:39:00Z
2011-11-25T15:39:00Z
2010
Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases / S.N. Kharin, Yu.R. Shpady, A.T. Kulakhmetova // Электрические контакты и электроды. — К.: ИПМ НАН України, 2010. — С. 123-131. — Бібліогр.: 7 назв. — англ.
XXXX-0085
https://nasplib.isofts.kiev.ua/handle/123456789/28894
517.958:[536.2+539.219.3]
The new criterion of arc stability and instability is introduced, which enables one to find arc duration dependently on given circuit parameters and properties of contact material. The mathematical model of phase transformations inside electrodes during arcing is elaborated which describes dynamics of arc erosion in metallic and gaseous arc phases. Increasing of arc duration and erosion with inductance occurs on account of enlarging of gaseous arc phase, while variation of metallic phase is relatively small.
Получен новый критерий стабилизации дуги, который позволяет найти зависимость продолжительности металлической фазы дуги от заданных параметров цепи и свойств контактного материала. Предложена математическая модель фазовых переходов внутри электродов в процессе горения дуги, которая описывает динамику дуговой эрозии в металлической и газовой фазах дуги. Установлено, что причвозрастания продолжительности дуги и эрозии контактов, происходящего с ростом индуктивности цепиявляется расширение газообразной фазы дуги относительно ее металлической фазы.
Отримано новий критерій стабілізації дуги, який дозволяє знайти залежність тривалості металічної фази дуги від заданих параметрів ланцюга і властивостей контактного матеріалу. Запропоновано математичну модель фазових переходів в середині електродів в процесі горіння дуги, яка описує динаміку дугової ерозії в металічній і газовій фазах дуги. Встановлено, що причиною зростання тривалості дуги і ерозії контактів, яке має місце із зростанням індуктивності ланцюга, є розширення газоподібної фази дуги відносно її металічної фази.
en
Інститут проблем матеріалознавства ім. І.М. Францевича НАН України
Электрические контакты и электроды
Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
Математическая модель температуры и электрической проводимости дуги в металлической и газовой фазах
Механічна модель температури та електричної провідності дуги в металічній і газовій фазах
Article
published earlier
spellingShingle Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
Kharin, S.N.
Shpady, Yu.R.
Kulakhmetova, A.T.
title Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
title_alt Математическая модель температуры и электрической проводимости дуги в металлической и газовой фазах
Механічна модель температури та електричної провідності дуги в металічній і газовій фазах
title_full Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
title_fullStr Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
title_full_unstemmed Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
title_short Mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
title_sort mathematical model of arc temperature and conductivity at metallic and gaseous arc phases
url https://nasplib.isofts.kiev.ua/handle/123456789/28894
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