Breakdown Voltage Measurements Research Articles

Molecular interactions of the antioxidant in the coolant oil for energy transformers: Dielectric and simulation studies

This research paper presents experimental and theoretical findings concerning the blending of mineral oil and vegetable oils, both with and without antioxidants. The study analyses a variety of parameters for different blends of mineral and vegetable oils, including breakdown voltage, ageing resistance, dielectric constant, viscosity, dissipation factor, surface tension, flash point, and fire point. The study was further extended to investigate the effects of varying the amount of antioxidants added to mineral oil blends with different vegetable oils. The best transformer insulating solution is found by extensive analyses that include measurements of breakdown voltage, flash point, fire point, and surface tension. This blends’ properties with antioxidant are either better than pure mineral oil or comparable to mineral oil. Density functional theory (DFT) analyses the molecular structure and dipole moment of an antioxidant. Molecular dynamics simulation method (MD) analysis of the average water residual time – periods of an antioxidant will show the stability of H-bond interactions. The primary objective of this experiment is to unveil a novel liquid-insulating material that not only excels in dielectric performance but also aligns with environmentally friendly practices.

Partial discharge characteristics from polymer insulator under various contaminant

The performance of polymer insulators can be significantly compromised by the presence of contaminants, resulting in damage, structural alterations, and accelerated aging. Hence, this research aimed to investigate the discharge behavior of polymer insulators when exposed to various types of contaminants. Three distinct contaminants, namely fly ash, salt, and algae, were prepared for the study. In order to assess the characteristics of these insulators, measurements of inception and surface breakdown voltages were conducted for each sample. Additionally, partial discharge measurements were performed at two different applied voltages to observe the patterns of partial discharge under different contaminants. To aid in distinguishing the characteristics of partial discharge, a statistical method based on graphical analysis was employed. Furthermore, visual inspection was carried out after the occurrence of partial discharge activity to provide an explanation for these phenomena. The findings of the study revealed that each contaminant produced a unique pattern, which was influenced by the specific elements present in the respective contaminant. It was observed that contaminants exhibit varying effects on partial discharge depending on their nature. Salt was found to induce faster stress propagation, fly ash inhibited stress propagation, and algae had a degrading effect on the surface of the polymer insulators.

Electrical breakdown voltage measurement in a contaminated transformers oil and thermal performance evaluation

Electrical breakdown voltage measurement in a contaminated transformers oil and thermal performance evaluation

Experimental and statistical investigation on the dielectric breakdown of magneto nanofluids for power applications

The insulating oil serves the dual purpose of providing insulation and cooling within transformers. This investigation aims to explore the impact of various nanoparticles on the dielectric breakdown voltage (BDV) of dielectric oils. The study examines the effect of the concentration of magnetic nanoparticles on the dielectric breakdown voltage of insulating oils. Nanoparticles such as iron (II, III) oxide (Fe3O4), cobalt (II, III) oxide (CO3O4), and ferrous phosphide (Fe3P) were utilized to create nanofluids with carrier mediums consisting of mineral oil and synthetic ester oil. BDV determination was conducted using a VDE and S–S electrode system according to IEC 60156 standards. Nanofluid were prepared using a two-step method, and their concentrations ranged from 0.01 g/L, 0.02 g/L, and 0.04 g/L in base oils. Twelve iterations were conducted for each prepared nanofluid, and breakdown voltage measurements were recorded. The results indicate a noteworthy enhancement in the breakdown voltage of nanofluids. The statistical analysis was performed on the dielectric property of nanofluid samples for better breakdown accuracy. The maximum enhancement at specific nanoparticle concentrations was shown by each nanofluid. The results show that under the S–S electrode configuration, the greatest overall enhancement was observed for Fe3P in mineral oil, with an enhancement of 70.05%, and Fe3O4 in synthetic ester oil, with an enhancement of 46.29%.

Demonstration of a simple and efficient design methodology for high‐voltage floating field limiting ring in SiC power devices

AbstractThis letter, proposes and experimentally demonstrates a simple and efficient estimating method for high‐voltage floating field ring (FFR). Four rings in FFR are used to determine the influence of rings’ distance (d) on the voltage drops of the highest voltage to the third ring (Vn+1) and the third to the second ring (Vn). Then, two voltage curves (curves for Vn+1 and Vn) based on d are drawn. For a target breakdown voltage, by iterating between the curves for Vn+1 and Vn, the number of FFRs and corresponding distances can be found. Based on this method, an 8.0 kV PN diode with 111 FFRs is designed and fabricated. The measured breakdown voltage is 7840 V, which reaches 98% of the designed value. This method provides a simple and efficient design for high‐voltage SiC devices, especially for ultra‐high voltage applications where the number of rings exceeds dozens.

Kilovolt-class β-Ga2O3 MOSFETs on 1-in. bulk substrates

We report on the demonstration of β-Ga2O3 MOSFETs fabricated on 1-in. bulk substrates using metalorganic vapor phase epitaxy (MOVPE) with disilane (Si2H6) as the silicon precursor. Sheet charge uniformity of the as-grown films was measured via Hall and ranged from 5.9–6.7 × 1012 cm−2 with a uniform Hall mobility of 125–129 cm2/V s across the sample. MOSFET devices with a source-drain length of 5.1 μm were measured across the wafer and had a minimum on-resistance (RON) of 47.87 Ω mm with a maximum on-current (ION) of 165 mA/mm. For these same devices, the on-current (ION) and pinch-off voltage (VP) uniformity across the wafer were 137 ± 12 mA/mm and −27.3 ± 7.3 V, respectively. Devices showed low reverse leakage current until catastrophic breakdown occurred, with measured breakdown voltages (VBR) of up to 2.15 kV. This work provides valuable insights into understanding the growth, fabrication, and characterization processes for β-Ga2O3 FETs on full wafer-scale substrates. It also projects the promise of developing lateral β-Ga2O3 FETs with high current-carrying capabilities and breakdown voltages, especially on substrates of 1 in. or larger.

Design, characterization and installation of the NEXT-100 cathode and electroluminescence regions

NEXT-100 is currently being constructed at the Laboratorio Subterráneo de Canfranc in the Spanish Pyrenees and will search for neutrinoless double beta decay using a high-pressure gaseous time projection chamber (TPC) with 100 kg of xenon. Charge amplification is carried out via electroluminescence (EL) which is the process of accelerating electrons in a high electric field region causing secondary scintillation of the medium proportional to the initial charge. The NEXT-100 EL and cathode regions are made from tensioned hexagonal meshes of 1 m diameter. This paper describes the design, characterization, and installation of these parts for NEXT-100. Simulations of the electric field are performed to model the drift and amplification of ionization electrons produced in the detector under various EL region alignments and rotations. Measurements of the electrostatic breakdown voltage in air characterize performance under high voltage conditions and identify breakdown points. The electrostatic deflection of the mesh is quantified and fit to a first-principles mechanical model. Measurements were performed with both a standalone test EL region and with the NEXT-100 EL region before its installation in the detector. Finally, we describe the parts as installed in NEXT-100, following their deployment in Summer 2023.

Unintended gas breakdowns in narrow gaps of advanced plasma sources for semiconductor fabrication industry

Occurrence of unintended gas breakdown in the narrow gaps of plasma processing chambers is one of the critical challenges in developing advanced plasma sources. We present a combined experimental and theoretical study of unintended discharges in the narrow gaps of plasma processing chambers and report significant drop of the gas breakdown voltage in the presence of a background plasma facing the gap. Experimentally measured breakdown voltages decrease in subsequent breakdown events due to wall erosion caused by the discharge. Therefore, preventing and mitigating the first discharge is of paramount importance. An analysis of kinetic simulation results indicates that the charged particle influx from the background plasma in the processing chamber into the gap is responsible for the onset of early breakdown: higher charged particle density within the gap modifies the electric field profile, allowing unintended breakdowns to occur at a significantly reduced threshold voltage.

Breakdown characteristics of nitrogen at different pressures in alternating non-uniform electric fields

Abstract AC breakdown characteristics of nitrogen at different pressures in electric fields with different degrees of non-uniformity provided by a sphere-plane electrode system have been investigated. It is found that the measured breakdown voltages obey Paschen’s law at the values of the field factor (the ration of the maximum field strength between electrodes to the average field strength) below ∼2. Deviations start to appear and increase gradually if the field factor increases above this threshold. Respectively, the dependence of the breakdown voltage U b on the product of pressure p and gap distance d changes from been linear U b ∼ p ×d to a more complex relationship of type U b ∼ p ×ln(d). It is found that the maximum field strength corresponding to the breakdown increases with increasing gas pressure and decreasing electrode radius but it is independent on the gap distance. The breakdown voltages predicted by the streamer criterion agree well with the experimental data. The results obtained for nitrogen were compared with the breakdown characteristics of air and it was found that at the values of the field factor below 9, the breakdown strength of nitrogen was higher than that of ambient air.

Molecular Orbital Properties and Insulation Characteristics of Flaxseed Oil

This study aims to analyze the molecular orbital parameters of flaxseed oil (linum usitatissimum) and to measure the AC breakdown voltages at different electrode gaps with various rate of rises. AC breakdown voltages of flaxseed oil are measured at 1.0 and 2.5 mm electrode settings with 0.5 kV/s, 2.0 kV/s and 3.0 kV/s rate of rises, adhering to IEC and IEEE standards. UV-VIS (Ultraviolet–Visible) and FT-IR (Fourier Transform-Infrared) measurement tests carried out after breakdown voltage measurements reveals that the molecular structure of the oil remains stable against electrical discharges. The compounds of flaxseed oil are analyzed using GC-MS and it is determined that the oil mainly consists of seven triglycerides in accordance with the literature. In order to better understand the electrical behavior of these triglycerides, molecular orbital properties such as ionization potential, electron affinity and electron energy gap are analyzed employing Density Functional Theory (DFT) using B3LYP/6-311 + G(d,p) and B3PW91/6-311 + G(d,p) basis sets. The advantages of flaxseed oil such as AC dielectric strength, stability against breakdown mechanism, homogeneous molecular electrical characteristics of its compounds and antioxidant content make this oil as one of the potential natural ester alternatives to mineral oils in the power system industry.

Pulsed photoemission induced plasma breakdown

This article characterises the effects of cathode photoemission leading to electrical discharges in an argon gas. We perform breakdown experiments under pulsed laser illumination of a flat cathode and observe Townsend to glow discharge transitions. The breakdown process is recorded by high-speed imaging, and time-dependent voltage and current across the electrode gap are measured for different reduced electric fields and laser intensities. We employ a 0D transient discharge model to interpret the experimental measurements. The fitted values of transferred photoelectron charge are compared with calculations from a quantum model of photoemission. The breakdown voltage is found to be lower with photoemission than without. When the applied voltage is insufficient for ion-induced secondary electron emission to sustain the plasma, laser driven photoemission can still create a breakdown where a sheath (i.e. a region near the electrode surfaces consisting of positive ions and neutrals) is formed. This photoemission induced plasma persists and decays on a much longer time scale ( s) than the laser pulse length ( ps). The effects of different applied voltages and laser energies on the breakdown voltage and current waveforms are investigated. The discharge model can accurately predict the measured breakdown voltage curves, despite the existence of discrepancy in quantitatively describing the transient discharge current and voltage waveforms.

Ignition detection with the breakdown voltage measurement during nanosecond repetitively pulsed discharges

Nanosecond Repetitively Pulsed Discharge (NRPD) is a promising ignition concept for introducing diesel-like process parameters for hard-to-ignite renewable fuels in Spark Ignition (SI) engines. Knowing whether an ignition event initiated by a series of nanosecond electrical discharges was successful or not gives the possibility of using this information for closed-loop ignition control. This paper presents a methodology for detecting successful ignition under NRPD ignition.After a nanosecond discharge, the heat loss from the particles (plasma-gas) between the electrodes and the surrounding gas is different if a robust flame kernel is established. If a flame kernel is present, the heat losses are lower, resulting in a lower local density of the gas between the electrodes. The breakdown voltage value of a nanosecond pulse is proportional to the local density. A control pulse is applied after the main ignition sequence to detect successful ignition. Lower breakdown voltages of the control pulse are present if a robust early flame kernel is present. The control pulse is applied before the pressure rises due to the presence of fast combustion, allowing ignition to be detected during the inflammation phase, thus allowing the possibility to place additional ignition events, if necessary.This technique was experimentally analyzed in a Constant Volume ignition Cell (CVC) and in a Rapid Compression Expansion Machine (RCEM). In the CVC at the ignitability limit, lower breakdown voltages of the control pulse are mostly measured when no pressure rise is measured. In the RCEM, the heat release rate is analyzed with a two-zone thermodynamic model, and the early flame kernel formation is monitored with Schlieren imaging. Some overlap exists in the control pulses' breakdown voltages for the ignition and quenching experiments; nevertheless, the Schlieren videos outline that the overlapping cases have a similar flame kernel formation, and the difference arises thereafter.

Prebreakdown and Breakdown Phenomena in HFO Gas Under Impulse Voltage—Part I: Divergent Field

Pre-breakdown and breakdown phenomena in HFO1234ze(E) gas are studied with a wide range of electrode geometries, characterized by a field enhancement factor η ranging from 1.7 (quasi uniform field) to 90 (very divergent field). As in SF6, breakdown in HFO results from the inception and propagation of leaders. Depending on the field geometry, the measured breakdown voltage represents either the voltage required for leader complete propagation (in divergent field, η > 10), or for inception (in quasi-uniform field, η < 10). This paper mostly concerns results obtained with divergent fields. Leader propagation in HFO is barely influenced by pressure, and the minimum voltage required for propagation to breakdown is slightly lower compared to SF6, explaining that lower breakdown voltages are recorded with HFO in divergent field. In such conditions, breakdown voltage is mainly determined by the gap distance. HFO degradation, evidenced by the formation of black soot after breakdown, has no influence on leader propagation, and hence on breakdown properties in divergent fields.

Highly Efficient Floating Field Rings for SiC Power Electronic Devices - A Systematic Experimental Study

A systematic experimental study is conducted on floating field rings (FFR) incorporated into 4H-SiC junction barrier Schottky (JBS) diodes across four voltage ratings 650, 1200, 1700 and 3300V, in pursuit of highly efficient FFR designs. 30 designs of FFR in 3 categories are studied for each voltage rating, and the measured breakdown voltage (Vbr) of JBS divided by ring system width (W) is taken as the figure of merit (FOM) of each design. The influence of ring spacing, ring width and number of rings on Vbr is studied in detail. It is found that the initial ring spacing (S1) is critical in determining the highest Vbr achievable by a certain design, and its optimum value increases as voltage rating increases. TCAD simulation verifies the importance of S1. For designs with a small ring system width, subsequent ring spacing can also become important. Ring width does not have a definitive effect, and Vbr saturates beyond a certain ring number. The design with the highest Vbr may not render the highest FOM. Even style designs with appropriate ring spacings can be advantageous likely due to less susceptibility to variation of field oxide charge, and more tolerance to fabrication error, as well as ease of design.

Convective heat transfer behavior and AC dielectric breakdown voltage of electric power transformer oil with magnetic colloidal nano-fluid: An experimental study

This research reports on an experimental investigation into the alternating insulation breakdown voltage (AC) and convective heat transfer behavior of nano-oil for application in electrical transformers. The base fluid of the examined nano-oil is nitro libra type transformer oil, one of the common mineral oils used in transformers. It contains iron oxide magnetic colloidal nanoparticles. Upon fabrication of the experimental apparatus in the lab, an experimental study on convection heat transfer is performed under laminar flow conditions and with a continuous heat flux applied to the wall. BA100 breakdown voltage measurement instrument based on the IEC 60156 standard is also used for alternating breakdown voltage testing. The current findings from the experimental investigation of convective heat transfer are compared with and verified by the experimental results available in the literature. The experimental results demonstrate that the convective heat transfer coefficient of the iron oxide magnetic nanoparticle-prepared nano-oil is on average 4.51% higher than that of base oil. These particles have an average size of 23 nm and a volume concentration of 0.1%. Additionally, compared to base oil, nano-oil with a volume concentration of 0.1% has a 23.8% higher dielectric breakdown voltage.

Optimized emitter-base interface cleaning for advanced Heterojunction Bipolar Transistors

Heterojunction Bipolar Transistors needed for high-frequency applications require precise dopant control. In-situ doped epitaxies used during device fabrication rely on surface preparation to obtain an optimized doping profile. Defects due to imperfect cleaning relates to high emitter resistance and low-frequency noise.Base epitaxy is followed by the fabrication of thin L-shaped oxide spacers and in-situ arsenic-doped emitter epitaxy by Low Pressure Chemical Vapor Deposition. A cleaning step between spacers formation and emitter epitaxy is mandatory to remove residual contamination. Hydrofluoric acid (HF) wet cleaning, in-situ remote plasma cleaning (SiconiTM) and thermal treatments have been tested. A minimum etching budget is sought for limiting spacer consumption while adequately cleaning the interface.Time Of Flight-Secondary Ion Mass Spectroscopy (TOF-SIMS) and High-Resolution Transmission Electron Microscopy (HR-TEM) are used to characterize the interface and measure levels of arsenic, oxygen, fluorine and carbon. Emitter resistance and base-emitter breakdown voltage measurements are used to show the impact on electrical figures of merit. Siconi targeting 10 Å of thermal oxide removal followed by a thermal treatment (800 °C, 60 s) in the deposition chamber results the best process among the tested ones.

Investigation of Discharge Propagation in Localized High-Temperature SF6 Gas With Breakdown Voltage Measurement

In high-voltage gas circuit breakers (HVCBs), high-pressure gas is blown between the electrodes to cool the arc. The temperature distribution between the electrodes at the current zero point has a large gas temperature difference. This study aims to experimentally clarify the effect of the cold gas region on the breakdown voltage of gases with large temperature differences. In an experiment, a hot gas generator using arc heat was used to create a gas space with a large temperature difference between electrodes, and the breakdown voltage was evaluated. The breakdown voltage in the gas space with a cold gas region was twice that of the case, where the space between the electrodes was filled with hot gas. It was found that the discharge initiated in the hot gas region was suppressed in the cold gas region and that the breakdown voltage in a gas space with the hot and cold region was influenced by the existence of the cold gas.

Measurements of breakdown voltage and critical current density in a water electrolysis varying area and shape of working electrode

This work investigated the influence of the working electrode on the partial contact glow discharge electrolysis (CGDE) using disk and rectangle shaped cathodes in a water electrolysis. The breakdown voltage and the critical current density (CCD), which are due to the initial formation of partial hydrogen film were measured together with in situ observation of hydrogen bubble behaviors. As the cathode area increased, the breakdown voltage increased regardless of shape of the cathode as the active area increased. By contrast, the CCD decreased at different rates depending on the cathode shape. The formation of the hydrogen bubble layer adjacent to the cathode surface elucidates this result. In case of the disk, the thickness of the bubble layer remarkably increased with increased cathode area, resulting in the CCD decrease since the partial hydrogen film was readily formed, while a trivial change of the bubble layer was observed in case of the rectangle. Thus, a milder decreasing trend of CCD was measured in case of rectangle cases than that of disk cases. The wetted perimeter per area (P/A) was introduced as a more generalized parameter affecting the CCD.

Preliminary Study on Spark Emission Characteristics for Measuring the Minimum Ignition Energy of a Hydrogen-Oxygen Combustible Mixture

The ignition energy of a hydrogen-oxygen combustible mixture is determined by the breakdown voltage and capacitor capacity measured using the spark ignition circuit. To measure the breakdown voltage, it is important to understand the attributes of the spark emission that occurs during ignition. Through this experiment, it was confirmed that the spark emission of a hydrogen-oxygen combustible mixture was divided into three stages: yield, arc, and glow. The breakdown voltage according to the hydrogen volume percentage of the hydrogen-oxygen combustible mixture was measured. Additionally, the ignition energy was measured by comparing the ignition energy calculation formula using the measured breakdown voltage and capacitor capacity with a formula suitable for the experimental conditions. Under these experimental conditions, the measurement of the minimum ignition energy required to ignite the combustible mixture is limited. The minimum ignition energy should be measured through the breakdown voltage at the minimum separation distance and a capacitor capacity of less than 1 pF.

Influence of discharge polarity on streamer breakdown criterion of ambient air in a non-uniform electric field

Streamer breakdown of atmospheric air with non-uniform dc electric field in a needle-to-plate electrode configuration is studied using a semi-analytic model and experimental measurements. A high voltage (either positive or negative) is applied to a hollow needle with outer diameter and inner diameter separated from a planar ground electrode by a gap distance of 0.1–1.4 cm. Breakdown voltages are recorded for both positive and negative discharge polarities. Empirical relations between the critical avalanche size for streamer breakdown and the gap distance are proposed. Using these empirical relations, a semi-analytic model based on Meek’s criterion for streamer breakdown is developed to accurately predict the measured breakdown voltages. It is found that for (or d 0.5 cm at one atmosphere) streamer breakdown of ambient air occurs at a lower applied voltage for a positively biased needle compared to that with a negatively biased needle, referred as the polarity effect. For breakdown is attained at a lower applied voltage with a negatively biased needle compared to that with a positively biased needle, and breakdown mode transits from the polarity effect to the so called inverted polarity effect.