Calculation Of Breakdown Voltage Research Articles

A simulation study of vertical Ga2O3 Schottky barrier diodes using field plate termination

The precision design of beta-phase gallium oxide (β-Ga2O3) power devices requires appropriate physical properties, including a breakdown electric field intensity. To clarify the breakdown electric field in β-Ga2O3, we fabricated vertical Schottky barrier diodes (SBDs) with a field plate (FP) on a β-Ga2O3 (001) epitaxial layer and simulated their breakdown situations under reverse bias. The calculated breakdown voltages of the SBD with a single FP were consistent with the experimental values when assuming an electric field criterion of 5 MV cm−1 in β-Ga2O3. By designing a SBD with a double FP according to the electric field criterion above, a breakdown voltage over 2 kV and specific on-resistance of 6.9 mΩ cm2 were realized simultaneously. This results in an electric field criterion that is useful for the design parameter of β-Ga2O3 devices to balance a high breakdown voltage and low on-resistance.

Numerical Calculation of Direct Current Breakdown Voltage for Complex Short Air Gaps under Varying Altitudes

With the increasing construction of ultra-high voltage direct current transmission in high-altitude environments, it becomes crucial to explore the impact of altitude on the short-gap discharge characteristics. To this end, this study proposes a finite element simulation and calculation method for the direct current (DC) breakdown voltage of actual complex short-gap structure under varying altitudes based on the Townsend criterion and the streamer criterion. The method is verified by combining the discharge experiments in Beijing, Qinghai, and Tibet. The results demonstrate that this method can effectively calculate the DC breakdown voltage of gaps between damping capacitors with a relative error range of -3.64% to 0.2%. The research results provide new insights for insulation evaluation of short-gap structures under varying altitudes.

Breakdown characteristics and voltage calculations of large-size sphere-plane long air gaps

Breakdown characteristics and voltage calculations of large-size sphere-plane long air gaps

Research and Analysis of Insulating Gas in Unified Test Conditions.

In order to study the insulation mechanism of SF6 substitute gas, it is suggested to calculate the dielectric strength of insulating gas from the molecular structure. The dielectric strength of a typical gas is modeled by a power frequency breakdown test under a uniform electric field. The molecular parameters of insulating gases are calculated by the density functional theory method, and the effect of molecular structure parameters on the breakdown voltage of power frequency is studied. Based on the molecular structure parameters, which are closely related to the breakdown voltage of power frequency, a model of pressure and distance variation of AC breakdown voltage of insulating gas is established. The breakdown voltages of insulating gases (CF3SO2F) are also derived from the proposed model. The calculated breakdown voltage of power frequency of two gases is compared with the experimental value. The average error is just 2.6%. This model provides a basis for the future search for potential alternative insulating gases.

The 3D graph approach for breakdown voltage calculation in BaTiO3 ceramics

After pioneering attempts for the introduction of graph theory in the field of ceramics and microstructures, where 1D and 2D graphs were used, in this paper we applied 3D graphs for the breakdown voltage calculation in BaTiO3 sample with some predefined constraints. We have described the relations between grains in the sample and established a mathematical approach for the calculation of breakdown voltage using experimental results. As a result, we introduced mapping between the property of sample and grain structure, then between the grain structure and mathematical graph, using various crystal structures. The main idea was to apply 3D graph theory for the distribution of electronic parameters between the neighboring grains. With this study, we successfully confirmed the possibilities for applications of graphs as a tool for the determination of properties even at the intergranular level.

Design of a Real-Time Breakdown Voltage and On-Chip Temperature Monitoring System for Single Photon Avalanche Diodes

The design and implementation of a real-time breakdown voltage and on-chip temperature monitoring system for single photon avalanche diodes (SPADs) is described in this work. In the system, an on-chip shaded (active area of the detector covered by a metal layer) SPAD is used to provide a dark count rate for the breakdown voltage and temperature calculation. A bias circuit was designed to provide a bias voltage scanning for the shaded SPAD. A microcontroller records the pulses from the anode of the shaded SPAD and calculates its real-time dark count rate. An algorithm was developed for the microcontroller to calculate the SPAD’s breakdown voltage and the on-chip temperature in real time. Experimental results show that the system is capable of measuring the SPAD’s breakdown voltage with a mismatch of less than 1.2%. Results also show that the system can provide real-time on-chip temperature monitoring for the range of −10 to 50 °C with errors of less than 1.7 °C. The system proposed can be used for the real-time SPAD’s breakdown voltage and temperature estimation for dual-SPADs or SPAD arrays chip where identical detectors are fabricated on the same chip and one or more dummy SPADs are shaded. With the breakdown voltage and the on-chip temperature monitoring, intelligent control logic can be developed to optimize the performance of the SPAD-based photon counting system by adjusting the parameters such as excess bias voltage and dead-time. This is particularly useful for SPAD photon counting systems used in complex working environments such as the applications in 3D LIDAR imaging for geodesy, geology, geomorphology, forestry, atmospheric physics and autonomous vehicles.

Calculation of Breakdown Voltage of Gas Gaps With Weakly Nonuniform Field: Sphere and Donut Gaps

Breakdown voltage (BDV) is calculated for two electrode structures, namely, sphere and donut gaps, operating in air at atmospheric pressure. The calculation is based on the streamer BD criterion. COMSOL software package is used for field analysis and calculation of critical number of electrons by assessing integrals of the efficient ionization coefficient along field lines. Thus, also lengths of critical avalanches that can propagate from both electrodes were obtained. First, simulations were performed for sphere gaps at conditions standardized by IEEE to derive critical number of electrons for highly reliable experimental data. It was shown that these numbers deviate greatly from the widely accepted 108 number, and that clear tendencies for the deviations exist depending on the gap to sphere diameter ratio. This assisted us in the second part of this work, which is a description of a spark gap (SG) formed by two donuts. Such gaps are compact and can serve as closing switches, and as a crude HV measurement means. Experimental results and comparison to calculated BDVs are reported. These two examples illustrate a simple and effective method of BDV calculation in arbitrary geometries with weakly nonuniform field for well-characterized gases at moderate pressures; it can be used with industry-standard software in HV practice.

Impulse breakdown of liquid water - influence of pulse duration and gap distance

In this study, the impulse breakdown of conductive water (350 μS/cm) was carried out under 25~1500 μs pulses and with a gap distance of 0.5~100 mm. The influence of pulse duration, gap distance and voltage polarity on the breakdown characteristics are shown. Martin's equation and streamer linear propagation (SLP) model for breakdown voltage calculation are compared, and their application conditions are indicated. The results show the pulse duration and the gap distance on the breakdown characteristics are opposite; however, their influence on voltage polarity are similar. Martin's equation is only appropriate for short impulse breakdown (nanosecond) while the SLP model is shown to be suitable for long impulse breakdown (microsecond or longer).

РАЗРАБОТКА И ИСПОЛЬЗОВАНИЕ МЕТОДА РАСЧЕТА НАПРЯЖЕНИЯ ТЕПЛОВОГО ПРОБОЯ В ВЫСОКОЧАСТОТНЫХ СТРУКТУРАХ

The paper deals with the description of a new technique of calculations of the heat release processes at the high and ultra-high frequencies associated with the losses in composite materials (CM) what may cause the destruction of radio components. The study of thermal breakdown is necessary to determine the mechanism and nature of change of dielectric properties. Thermal breakdown influences destructively the composite material radio components or even causes their failure. The heating phenomena are rather complex and the calculation of its origination mechanism, as well as the stages of the origination and development of thermal effect and composite material aging, are scientifically and practically attractive. The goal of the study is the development of a technique for calculation of heat removal and thermal breakdown voltage in the high-frequency structures both for a structure cooled from the one side and for a structure cooled from two sides. The author got the formulas for calculation of the thermal breakdown voltage of the small-size insulators both in the cases when the electric field is uniform and in the cases when it is non-uniform. It is experimentally proved that when increasing the temperature of the environment, the value of thermal overload decreases for the composite dielectric materials. When increasing the frequency, the temperature differential increases; at the high frequencies, large temperature differentials occur in the structures made of composite dielectric materials that cause the destruction. The calculation technique proposed by the author ensures the calculation accuracy sufficiently high for the practical purpose. The study of the breakdown of the discoid components made of a composite containing titanium dioxide shows that in the interval of frequencies f from 0.5 to 1.5 MHz, the temperature and frequency dependencies of thermal breakdown voltage are compliant with the calculations according to the proposed technique.

Systematic investigation of the effect of N2 admixture ratio on barrier discharge in helium

The influence of the N2 admixture ratio on a He–N2 uniform atmospheric pressure glow discharge (APGD) generated using an asymmetric 20 µs, 10 kHz bipolar applied voltage pulse is systematically investigated, using electrical and optical emission spectroscopic measurements as diagnostic tools. We focused our investigation on understanding the discharge characteristics of the plasma ignited after an off-voltage period of 80 µs duration. The measured breakdown voltages for various N2 admixture ratios of up to 3% are compared with a theoretically calculated breakdown voltage, taking into account the secondary electron emission coefficient of the dielectric surface. The results indicate that the value of the secondary emission coefficient should increase from 0.1 to 0.5 to realize the experimentally obtained breakdown voltage variation within a 3% N2 admixture ratio. Using experimentally obtained values of the breakdown voltage, discharge current densities for different N2 admixture ratios, and 66 reactions among electrons, helium and N2, the variations of the N2 (A), N2 (C) and (B) state densities with N2 admixture ratio are calculated. The N2 admixture ratio dependence of the calculated N2 (C) and (B) state densities are similar to the N2 admixture ratio dependences of the emission intensities of the 337 nm band of the N2 second positive system (SPS) and the 391.4 nm band of the first negative system, respectively. Experimental observation and numerical investigation indicates that below a 1% N2 admixture ratio, the He (23S) metastable state has a strong influence on the discharge characteristics, and above a 2% N2 admixture ratio, the N2 (A) metastable state influences the discharge behavior. The N2 (A) metastable state density is estimated experimentally using the emission intensity ratio of the 337 nm band of N2 SPS and the 247 nm band of a NO-γ system. The experimentally estimated and theoretically calculated value of N2 (A) metastable state density is of the same order of 1013 cm−3. The estimated N2 (A) metastable state density shows a rapid increase above a 2% N2 admixture ratio, which supports the idea that the secondary emission coefficient increases due to an increase in N2 (A) flux.

Impact ionization coefficients of 4H-SiC in a wide temperature range

The temperature dependence of impact ionization coefficients of electrons and holes along 4H-SiC 〈0001〉 was determined in a wide temperature range from 156 K to 561 K. Photomultiplication measurements were conducted using several types of 4H-SiC photodiodes (PDs) with different structures under high vacuum conditions. The hole ionization coefficient showed a negative temperature dependence, which can be attributed to enhanced phonon scattering at elevated temperatures. Temperature dependence of the electron ionization coefficient was small, and this result may be ascribed to the simultaneous effects of enhanced phonon scattering and shrinkage of minigaps in the conduction band. Accuracy of the obtained results was verified by comparing the calculated breakdown voltage with the experimental breakdown voltage of various diodes.

Sensitivity of modeled microscale gas breakdown voltage due to parametric variation

Device miniaturization increases the importance of understanding and predicting gas breakdown and electrical discharge thresholds. At gap sizes on the order of ten microns at atmospheric pressure, field emission drives breakdown rather than Townsend avalanche. While numerical and analytical models can demonstrate this transition, a quantitative understanding of the relative importance of each parameter remains unclear. Starting from a universal model for gas breakdown across the field emission and Townsend avalanche regimes [A. M. Loveless and A. L. Garner, Phys. Plasmas 24, 113522 (2017)], this paper applies the concept of error propagation from ionizing radiation measurements to determine the relative impact of each factor on the predicted breakdown voltage. For limits of both large and small products of the dimensionless ionization coefficient, α¯, and gap distance, d¯, the electrode work function has the largest relative effect on the predicted breakdown voltages with a deviation of 50% in the work function resulting in an uncertainty in the calculated breakdown voltage of ∼84% for both α¯d¯≫1 and α¯d¯≪1. This quantifies the significance of nonuniformities in material surfaces and changes in the surface structure during multiple electric field applications and help predict the breakdown voltage for small gaps, motivating better electrode characterization both initially and during repeated operation.

Sensitivity Analysis of Breakdown Voltage Calculations for Liquid Nitrogen

Liquid nitrogen is applicable as coolant and insulation for high-temperature superconductors and offers a more economical alternative to liquid helium. For failure prevention, knowledge of the electrical withstand capability is required, which can be acquired through experiments. These experiments showed that there are a lot of influence factors on the breakdown voltage. Experiments conducted at this institute, covering some of these influences, have been already presented in several other works. These experiments, combined with the available scientific literature, led to the evolution of practically oriented formulas to calculate the breakdown voltage in liquid nitrogen with and without gas bubbles. In this paper, the evolution of the aforementioned formulas is presented in addition to an explanation of their respective background. Furthermore, possible influences on the breakdown voltage found in the formulas are emphasized. Then, the degree of effect that these influences have on the calculated breakdown voltages is calculated and presented. Finally, a ranking of these parameters is given, as assistance to check experimental conditions and to evaluate theoretical results.

Calculations of breakdown voltage of rod-plane air gaps in the presence of water streams

A breakdown model of rod-plane air gaps in the presence of water streams has been established. Water streams which do not fully cross air-gaps are considered. This model involves the breakup length and surface conductivity of a water stream, the stream’s diameter, the number of the water droplets in the remaining air gap and the distance between two adjacent water droplets. The breakdown voltage is considered in two parts: one being the voltage drop along the water stream surface, and the other the voltage drop across the remaining air gap. To study the two components of voltage drop, the equivalent surface conductivity of a water stream and the voltage-current characteristics between two water droplets were investigated. Additionally, theoretical and experimental results are compared and it has been found that under the conditions considered, the breakdown voltages are predictable to within 13%. Evidence regarding the impact of radial dispersion of droplets and their distortion on the breakdown process is considered.

Experimental study on breakdown voltage between parallel plates in high-pressure helium

To obtain the base data for insulation design of the electrical equipment used in the high temperature gas cooled reactor nuclear power plant, an experimental apparatus for testing helium insulation property under high pressure is designed. The apparatus is composed of a pressure vessel, a heating system, an electrical penetration assembly, a vacuum pump, a pressure gauge, a safety pressure valve, a release valve, and a helium bottle. The highest pressure that the vessel can hold is 10 MPa, and in this experiment the safety pressure valve is set to be 8 MPa. The temperature inside the vessel can be heated to 200 ℃ by a heating system. The resolution of the pressure gauge is 1 kPa, and the highest pressure that the gauge can measure is 9.999 MPa. The purity of the helium used in this experiment is 99.999%. The breakdown voltage of helium gas between two parallel plane electrodes is measured by the apparatus under the conditions of 15-20 ℃ and 0.1-7 MPa. The electrodes are made of copper, and their diameters are both 100 mm. The distances between the parallel electrodes are 0.25 mm, 0.35 mm and 0.5 mm respectively. The error of the distance is less than 0.01 mm. The DC voltage between the electrodes is supplied by GPI-735A, a withstand voltage and insulation tester produced by GW Instek corporation. The voltage increases slowly from 0 to 6000 V (highest), until the current more than 0.1 mA is detected. The highest voltage recorded is the breakdown voltage. With other researchers’ experimental data under low pressure, the Paschen equation for helium gas is obtained. It is found that the calculated breakdown voltage for this equation is larger than the experimental result in this paper under high pressure. And the deviation becomes larger as the product of the pressure and the distance increases. Firstly, it is because the ionization coefficient γ in the equation is influenced by the gas pressure. Secondly, because of larger areas of electrodes, worse surface roughness and less electrode distance, under the same product of the pressure and the distance, the breakdown voltages in this paper are less than the ones in other researches, which are the base of the calculated values. The Paschen equation is modified to accord with the values under high pressure. Under high pressure, the Paschen curve is almost a straight line. A linear equation is presented for calculating the breakdown voltages of helium gas under 0.1-7 MPa. And an equation is presented to calculate the slope of the line. The slope is influenced by the collision cross section, the ionization energy and the temperature of the helium. The experimental data also show that the breakdown voltage of helium is far lower than that of air under the same condition. As the pressure increases, the breakdown voltage of helium increases. The value of helium under 3 MPa is equal to the one of air under atmosphere, and the value of helium under 7 MPa is about twice as high as that of helium under 3 MPa. So, it is possible to replace some experiments or tests under high pressure helium by the same operations under atmospheric air.

The Influence of Inert Gas Addition on Electric Breakdown Utilizing Dielectric Barrier Discharge in Ozone Generation in Air

This article investigates the effect of inert gas addition He, Ar, Kr, and Xe on gas breakdown voltage within a dielectric barrier discharge reactor with air feed gas. The density-normalized effective ionization coefficients are calculated for inert gas/air mixtures; the critical reduced field is then obtained where the electron ionization exactly balances the attachment. Adding inert gases would lead to the decreasing critical reduced field strength due to the enhancement of effective ionization coefficient. In addition, inert gas additions have shown to reduce the breakdown voltage. Moreover the calculated breakdown voltage values and the experimental data are plotted for the sake of comparison and results show that calculated results are in agreement with the experimental values. Parametric studies offer substantial insight in plasma physics, as well as in ozone generation applications.

Effect of Coating of Earthed Enclosure and Multi-Contaminating Particles on Breakdown Voltage inside Gas Insulated Bus Duct

Metallic particle contamination is one of the areas of insulation design that are considered critical. This paper demonstrates the control of metallic particles in gas insulated bus duct (GIBD) by using dielectric coating on the inside surface of the outer enclosure of a coaxial electrode system. Several models of GIBD with single and multi-contaminating particles will be studied. In this paper, the Finite Elements Method (FEM) is used to evaluate the electric field distribution on and around single and multi-contaminating wire particles which in contact with dielectric coating of earthed enclosure inside GIBD. The effect of changing the length and the radius of middle particle for multi-contaminating particles on the electric field values are studied. Breakdown Voltage calculations for gas mixtures with single and multi-contaminating wire particles are studied. The effects of gas pressure on the breakdown voltage for various fractional concentrations of SF 6 -gas mixtures with and without particle contamination and also with and without coating of earthed enclosure are studied. The optimum gas mixture which gives higher dielectric strength with lower cost is also determined. The effect of coating thickness of earthed enclosure on the breakdown voltage for various fractional concentrations of SF 6 -gas mixtures is also studied. Finally, the effect of length and hemi-spherical radius of multi-contaminating particles on the breakdown voltage with various SF 6 -gas mixtures and varying gas pressure one time and another time with fixed pressure are studied. DOI: http://dx.doi.org/10.11591/ijece.v4i4.5693

Temperature Dependence of Impact Ionization Coefficients in 4H-SiC

Impact ionization coefficients of 4H-SiC were measured at room temperature and at elevated temperatures up to 200°C. Photomultiplication measurement was done in two complementary photodiodes to measure the multiplication factors of holes (Mp) and electrons (Mn), and ionization coefficients were extracted. Calculated breakdown voltage using the obtained ionization coefficients showed good agreement with the measured values in this study, and also in other reported PiN diodes and MOSFETs. In high-temperature measurement, breakdown voltage exhibited a positive temperature coefficient and multiplication factors showed a negative temperature coefficient. Therefore, extracted ionization coefficient has decreased which can be explained by the increase of phonon scattering. The calculated temperature dependence of breakdown voltage agreed well with the measured values not only for the diodes in this study, but also in PiN diode in other literature.

Research on spark discharge of floating roof tank shunt

In order to quantitatively analyze the spark discharge risk of floating roof tank shunts, the breakdown voltage of shunt has been calculated by Townsend theory, the shunt spark discharge experiment is carried out by using 1.2/50 μs impulse voltage wave, and the relationship between breakdown voltage of shunt spark discharge and air gap is analyzed. It has been indicated by theoretical analysis and experimental study that the small gap is more easily cause spark discharge than the big gap when the contact between shunt and tank shell is poor. When air gap distance is equal to 0.1 cm, average breakdown voltage is 5280 V. When the air gap distance is less than 0.3 cm, experiment data agree well with Townsend theory. Therefore, in the condition of small gap, Townsend theory can be used to calculated breakdown voltage of shunt. Finally, based on the above conclusions, improvements for avoiding the spark discharge risk of shunt of floating roof tanks have been proposed.

Particle Intiated Breakdown Inside Gas Insulated Switchgear for Various Gases Mixtures

SF6 gas insulated switchgear plays an important role in electric power networks all over the world due to its merits as compared to traditional air insulated switchgear.The mixtures composed of a strongly electronegative gases with high dielectric strength such as SF6 and two ordinary gases such as N2 and Air or CO2 and Air with a various fractional concentrations are used in this paper to reduce the gas price and liquefaction temperature. From this point of view, various types of gas mixtures are used inside gas insulated switchgear (GIS) to give a higher dielectric strength. In this paper, the Finite Elements Method (FEM) is used to evaluate the potential and electric field distributions on and around contaminating filamentary wire particle at two positions, first is resting on the earthed plate and second is hovering inside the gap. The effects of particle dimensions such as (length, radius) and gap spacing on the electric field values are also studied. The breakdown voltage calculations under uniform field in case of clean gap and non-uniform field in case of gap with particle contamination are studied. The effects of gas pressure, SF6 gas concentration in mixture, gap spacing and particle dimensions on the breakdown voltage calculations are also studied.