Finite-Difference Time-Domain Simulation of a Lightning-Impulse-Applied ZnO Element

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The voltage generated across a zinc-oxide (ZnO) element, in which a lightning impulse current flows, has been computed with the finite-difference time-domain (FDTD) method. Also, the distribution of temperature in the ZnO element has been computed on the basis of FDTD-computed conduction current densities with a discretized heat equation. The ZnO element having a thickness of 37 mm and a diameter of 34 mm is represented with many 1 mm × 1 mm × 1 mm cubic cells, each of which has a nonlinear resistivity in each of the x , y, and z directions dependent on the electric field in each direction and the temperature in each cell. Waveforms of voltage appearing across the ZnO element and the temperature on the side surface of the ZnO element computed for a short lightning impulse current having a magnitude of 66 kA agree reasonably well with the corresponding measured ones.

Section: Introductionmentioning

confidence: 99%

Electromagnetic and Thermal Analysis of a ZnO Element of Transmission‐Line Arrester for a Lightning Surge Current

Saito

Tanaka

Tosa

et al. 2021

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“…[2,3], the finite-difference time-domain (FDTD) method [4] has been applied to electromagnetic and thermal simulations of MOV for short-tail lightning impulse currents such as an 8/20-μs current. In the simulations, an MOV element was represented as a combination of many small cells, each of which had a nonlinear resistivity depending on the magnitude of the electric field in the x , y, and z directions [2,3,5]. The heat generated in the MOV was computed using the discretized heat transport equation [6].…”

Section: Introductionmentioning

confidence: 99%

“…E-mail: ybaba@mail.doshisha.ac.jp *Doshisha University, Kyotanabe Kyoto, 610-0394, Japan **Otowa Electric Co., ltd., Hyogo, 661-0976, Japan computed from the instantaneous values of injected current density and resultant electric field, the latter of which is obtained with the approximate mathematical expression of the nonlinear relation between conduction current density and electric field [7,8]. Since no numerical computation method for solving Maxwell's equations is used to find the transient current distribution in the MOV, the present computation is efficient in comparison with those of [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…The heat generated in the MOV was computed using the discretized heat transport equation [6]. If the method is directly used to compute the electromagnetic and thermal responses for long‐duration currents such as a 10/350‐μs impulse current or a 2‐ms rectangular impulse current, it will take significant computation times because of pico‐second time increments needed for electromagnetic computations [2,3] (while much longer time increments can be used for thermal computations).…”

Section: Introductionmentioning

confidence: 99%

“…[s], P d is the absorbed power per unit volume [W/m 3 ], ρ m is the mass density [kg/m 3 ], C m is the specific heat [J/(kg K)], κ is the thermal conductivity [W/(m K)], α = κ/ (ρ m C m ) is the thermal diffusivity [m 2 /s]. In(2), P d at the time step n + 1 is computed by multiplying the injected current density and resultant electric field at each cell computed with(1). Note that, the convective boundary condition is applied to the surface of the material[6].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Simplified Thermal Computation of a Metal Oxide Varistor Element under a Lightning Impulse Current Injection

Tanaka

Baba

Tsujimoto³

et al. 2021

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A simple thermal computation procedure of a metal oxide varistor (MOV) element, in which an impulse current is injected, is presented. The heat in the MOV, composed of many small cells, is computed with the discretized heat transport equation. At each time step, the injected impulse current is assumed to be distributed uniformly in the MOV. The power per cell is computed from the instantaneous values of injected conduction current density and resultant electric field, the latter of which is obtained with an approximate expression of the nonlinear relation between conduction current density and electric field. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Numerical Analysis of Electromagnetic Field, Heat and Thermal Stress of a Transmission Line Surge Arrester for Lightning Currents

Nishimura

Baba

Shinjo

2023

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The voltage across a 77‐kV‐class transmission line surge arrester (TLSA) and the heat in the TLSA have been computed using the finite‐difference time‐domain (FDTD) method for a lightning current having a magnitude of 50 kA, a risetime of 1 μs, and a half‐peak width of about 100 μs. The TLSA is represented with series‐connected‐nine ZnO elements, each of which has a length of 36 mm and a diameter of 32 mm. The ZnO element is represented with many 2 × 2 × 2 mm cubic cells, each of which has a nonlinear resistivity in each of the x‐, y‐, and z‐directions dependent on the electric field in each direction and the temperature in each cell. From the spatial and temporal distributions of FDTD‐computed heat in the TLSA, the spatial and temporal distributions of thermal stress in the TLSA have been computed using the finite‐element method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.