High Voltage Test Research Articles

CORONATING VOLTAGE DIVIDER OF MEGAELECTRONVOLT ACCELERATING TUBE

This paper describes the methodology of high-voltage testing of the voltage divider of a positively charged ion accelerating tube for energies up to 1000 keV. The test results are presented, and a simple engineering method for calculating the corona voltage divider is proposed.

Measurement of pulse current during high voltage tests using Rogowski coil with non-inverting integrator

The work is devoted to the development and modelling of the system of pulse current measurement during high-voltage tests and experiments. The proposed measurement system is based on the application of Rogowski coil with non-inverting integrator. The results of numerical modelling of the developed current measurement system are compared with the results of application of a low-inductance shunt resistor, Rogowski coil with passive RC-integrator and Rogowski coil with inverting active integrator in similar measurement systems. Various standard pulse currents including steep edge pulse (1/20 µs), large amplitude current pulse (4/10 µs), lightning pulse current (8/20 µs), switching pulse current (30/80 µs), and 1-3 ms pulse currents are modelled for the comparative test. From the simulation results, it follows that the developed Rogowski coil with the proposed non-inverting integrator has sufficiently high accuracy in a wide frequency band overlapping the frequency band of standard pulse currents in high-voltage tests.

Extraction and characterization of Cucumis melon seeds (Muskmelon seed oil) biodiesel and studying its blends impact on performance, combustion, and emission characteristics in an internal combustion engine

This study examines the performance, combustion, and emissions characteristics of a single-cylinder internal combustion diesel engine when fueled with a blend of diesel and biodiesel derived from muskmelon seeds. The kinematic viscosity of the extracted muskmelon seed oil was 6.1 cSt at 40 °C, which is higher than the kinematic viscosity of petroleum diesel of 2.6 cSt. Muskmelon biodiesel was further analyzed using thin-layer chromatography (TLC) and high-voltage separator tests. A comparison of the fuel properties of muskmelon biodiesel with conventional diesel fuel revealed that muskmelon biodiesel could be used alone or in a diesel–biodiesel blend to fuel compression diesel engines. In this study, muskmelon seed biodiesel was blended with diesel fuel at proportions of 10 %, 20 %, and 50 % (BD10, BD20, and BD50, respectively). At a relatively low rotational speed of 1200 rpm, the brake thermal efficiency (BTE) of the engine operated with BD10 and BD20 blends were 36.1 % and 36.0 %, respectively, while the brake-specific fuel consumption (BSFC) of the two blends were 0.260 kg/kWh, and 0.262 kg/kWh, respectively. These values closely resemble those typically observed in diesel fuel engines. Indeed, the average BTE of the BD20 blend was only 3.24 % less than the average BTE of diesel fuel. Diesel fuel generates less NOx and SO2 emissions compared to biodiesel blends: BD100 emitted the most NOx pollution of all fuels tested. In addition, BD10 released significantly more SO2 emissions compared to the other fuels tested. However, the BD20 blend outperformed all other blends in terms of CO, NOx, and SO2 emissions at high engine speeds. The only exception was H2S emissions, which were higher than BD50 and BD100. BD20 also exhibited significantly reduced CO emissions compared to diesel fuel, while BD10 emitted significantly more CO emissions than the other biodiesel blends. Our findings revealed that BD20 exhibited the best engine performance and lower emissions among all fuels tested. In other words, BD20 is the ideal fuel blend for use in diesel engines and does not require any alterations to the engine. Muskmelon waste seeds represent a non-edible waste stream that can be exploited in the production of biodiesel fuel, allowing for the upcycling of a potentially problematic thermochemical conversion feedstock. This potentially valuable use for waste muskmelon seeds in the energy sector could address the wastefulness associated with this particular waste stream.

Mathematical Modeling of SOIC Package Dynamics in Dielectric Fluids during High-Voltage Insulation Testing

The efficient testing and validation of the high-voltage (HV) insulation of small-outline integrated circuit (SOIC) packages presents numerous challenges when trying to achieve faster and more accurate processes. The complex behavior these packages when submerged in diverse physical media with varying densities requires a detailed analysis to understand the factors influencing their behavior. We propose a systematic and scalable mathematical model based on trapezoidal motion patterns and a deterministic analysis of hydrodynamic forces to predict SOIC package misalignment during automated high-voltage testing in a dielectric fluid. Our model incorporates factors known to cause misalignment during the maneuvering of packages, such as surface tension forces, sloshing, cavity formation, surface waves, and bubbles during the insertion, extraction, and displacement of devices while optimizing test speed for minimum testing time. Our model was validated via a full-factorial statistical experiment for different SOIC package sizes on a pick-and-place (PNP) machine with preprogrammed software and a zero-insertion force socket immersed in different dielectric fluids under controlled thermal conditions. Results indicate the model achieves 99.64% reliability with a margin of error of less than 4.78%. Our research deepens the knowledge and understanding of the physical and hydrodynamic factors that impact the automated testing processes of high-voltage insulator SOIC packages of different sizes for different dielectric fluids. It enables improved testing times and higher reliability than traditional trial-and-error methods for high-voltage SOIC packages, leading to more efficient and accurate processes in the electronics industry.

Improvement of Methods and Devices for Multi-Parameter High-Voltage Testing of Dielectric Coatings

Currently, the high voltage testing method is widely used to detect pinholes and porosity defects in dielectric coatings. However, most modern coatings also have requirements for the minimum allowable coating thickness. Conducting tolerance tests on the thickness of dielectric coatings concurrently along with monitoring integrity within a single technological process appears promising. Additionally, mitigating the impact of various interfering parameters is crucial. This paper conducts a theoretical and experimental examination of spark formation processes in both gas and dielectrics. This analysis takes place during the identification of both through and non-through defects in dielectric coatings on conductive substrates. The principles of selecting the test voltage for the investigated dielectric coatings, considering the need to detect both through defects and inadmissible thinning, are theoretically and experimentally justified. It is suggested to utilize a probabilistic approach for evaluating the detectability of the mentioned defects. It is demonstrated that, when the dielectric strength of the coating is known, it is feasible to identify both through and non-through defects in coatings with a calculated probability under a specified test voltage. The conditions of occurrence of partial discharges in the process of testing are investigated, and measures to suppress their influence on the inspection results are proposed. The influence of the substrate surface roughness on the magnitude of the breakdown voltage during testing is considered.

Numerical simulation of a positive streamer discharge in a combined gap based on aircraft lightning zoning test

The research involves conducting high voltage tests to determine lightning attachment locations on an aircraft model and constructing a streamer discharge simulation model in a 20 cm combined gap. The investigation focuses on the air streamer discharge of a non-uniform electric field in the combined gap through experiments and numerical simulation. The results reveal that the discharge process in the electrode-aircraft model gap closely aligns with the final jump stage of natural lightning. Notably, the surface charge density on the aircraft model exhibits a negative correlation with the radius of curvature. Due to the enhanced electric field strength, the aircraft model tips with bigger curvatures have a greater likelihood of initiating streamer discharge. Once the streamer bridges the electrode-aircraft model gap, the accumulation of space charge results in the aircraft’s surface charge reaching an order of magnitude higher than the initial induced charge.

A High Vacuum, High Electric Field Pulsed Power Interface Based on a Ceramic Insulator

Improving the flashover voltage in a vacuum interface between a pulsed-power system and a vacuum region has been a goal for many years. The interface problem is difficult because of the electrical, mechanical, and vacuum issues that must be satisfied simultaneously. In this paper, according to the theories of vacuum flashover and the design rules for high electric field insulators, a ceramic insulated vacuum interface is presented. The electrostatic field along the ceramic surface was obtained by ANSYS simulations. By optimizing the field shaper and shielding rings, the electric fields were well distributed and the fields around the cathode and anode triple junctions were effectively controlled. The high voltage test was carried out on a ~40 GW, ~100-ns pulser, and results show that the vacuum interface can work stably with the hold-off voltage of 600 kV. The experimental results agree with the theoretical and simulated results. Finally, the influence of the surface treatment on the ceramic flashover characteristics was also discussed.

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

Historically, streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis, with limited attention paid to the sphere-plane gap at high altitude analysis. In this work, sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage (UHV) test base at an altitude of 2200 m. The experiments measured the physical parameters such as the discharge current, electric field intensity and instantaneous optical power. The duration of the dark period and the critical charge of streamer-to-leader transition were obtained at high altitude. Based on radial thermal expansion of the streamer stem, we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude, and calculated the stem temperature, stem radii and the duration of streamer-to-leader transition. Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m, the error rate of the modified model was 0.94%, while the classical model was 6.97%, demonstrating the effectiveness of the modified model. From the comparisons and analysis, several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

Selection of Methods and Standards for the High-Voltage Testing of Polymer Insulators

Selection of Methods and Standards for the High-Voltage Testing of Polymer Insulators

Efficient Zero-Sequence Impedance Measurement in Autotransformers Using Low-Voltage Excitation

In accordance with the IEEE standard, the zero-sequence impedance test of transformers necessitates an open or short circuit test on the high-voltage side winding. Power source excitation is applied to the high-voltage test winding using a high-capacity test power supply. To circumvent the need for a large-capacity, high-voltage test power supply in field tests, this paper proposes a method for measuring zero-sequence impedance in autotransformers based on low-voltage excitation and disconnection testing. By applying a three-phase power supply to the lowest voltage side of the autotransformer and creating a disconnection condition, an unbalanced test scenario is established. Subsequently, the composite sequence network equivalent circuit for one-phase and two-phase disconnections between the high-voltage side and the low-voltage side of the transformer is formulated. Calculation formulas for the zero-sequence impedance of the autotransformer under various conditions are derived. The accuracy of the zero-sequence impedance is verified using MATLAB/Simulink simulation software 2018b, evaluating double-winding and three-winding autotransformers in breaking tests under different connection modes. The error is found to be less than 3%. The results of this study affirm the high accuracy of the proposed method.

Multipoint adsorption constructs stable interface chemistry for high-nickel cathode material

LiNi0.83Co0.12Mn0.05O2 (NCM), a common commercial material, has been applied widely in electric mobility and large-scale energy storage fields with its high energy density and voltage platform. Nonetheless, the battery life of long-term operation is significantly harmed by the unstable crystal structure and cathode-electrolyte interface. Among these, capacity decay is closely associated with the dissolution of transition-metal ions. In the present work, a surface-modified strategy is proposed, that is, ethyl α-cyanoacrylate (ECA) is adsorbed to the transition metal site by polar functional group and then initiates its polymerization to obtain poly(ethyl α-cyanoacrylate) (PECA) coating. The functional coating can lessen the degradation of interface by-products and construct a thinner CEI film for lithium-ion fast conduction. Furthermore, the conformal and complete coating alleviates the structural degradation after the long-term cycle. The above benefits explain the improved performance of PECA modified material and perform well even at high-temperature and high-voltage tests, thus reflecting that the modification strategy provides practical guidance for improving the performance of lithium-ion power batteries.

Generator Stator Partial Discharge Pattern Recognition Based on PRPD-Grabcut and DSC-GoogLeNet Deep Learning

Partial discharge (PD) pattern recognition of typical defects from generator stator bars is the basis of generator condition monitoring and fault diagnosis. A PD pattern recognition method for generator stator bars based on a phase-resolved partial discharge graph cut (PRPD-Grabcut) and Depthwise Separable Convolution GoogLeNet (DSC-GoogLeNet) deep learning neural network is proposed in this paper. First, five typical defects are designed on stator bars in the laboratory. A long-term high voltage test is carried out, and 37500 PRPD original graphs are obtained. Second, a PRPD-Grabcut method based on image segmentation is proposed, which is designed to extract key components of the PRPD map. Finally, a DSC-GoogLeNet based PD pattern recognition method is proposed, which combines the GoogLeNet inception module and depth-wise separable convolution. Experimental results show that the PRPD-Grabcut contributes to certain improvements in the recognition accuracy and training efficiency of the neural network. The DSC-GoogLeNet shows superiority in recognition accuracy, cross-entropy loss, and training time compared to a variety of existing lightweight neural networks. In addition, compared with other networks, the DSC-GoogLeNet greatly improves the recognition accuracy of PD types with similar but different risk levels for stator insulation.

DEVELOPMENT OF A TESTER FOR DIAGNOSTICS OF CABLE LINES STATE WITH XLPE INSULATION

Link for citation: Konev A.A., Khakimyanov M.I. Development of a tester for diagnostics of cable lines state with XLPE insulation. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 9, рр. 216-223. In Rus. Relevance. The moral and physical deterioration of cable lines voltage of 6–10 kV in our country ranges from 40 to 80 %. At the same time, up to 63 % of all accidents in electrical equipment are due to cable line failures. Recently, cables with cross-linked polyethylene insulation have been actively used, for the diagnosis of which special approaches are required. Therefore, the issues of developing high-voltage test facilities for diagnosing the state of insulation of electrical equipment are quite relevant. The authors proposed an original design of a high-voltage test facility that allows generating both direct voltage and alternating voltages of industrial and ultra-low frequencies. A feature of the device is the use of a multifunctional integrated electromagnetic component in it, which combines the functions of both an inductor and a capacitor. The use of this component allows reducing the dimensions and weight of the test facility. The main aims of the research are to develop a design of a high-voltage test facility and to study its characteristics; build a mathematical model and get dependency graphs. Objects: cables with XLPE insulation, high voltage test facilities. Methods: theory of electrical circuits, mathematical modeling, program for mathematical and engineering calculations Mathcad, MATLAB Simulink. Results. The authors proposed the original design of a high-voltage test facility, which makes it possible to generate both direct voltage and alternating voltages of industrial and ultra-low frequencies. The simulation of the installation was carried out. A method for calculating high-voltage test facilities is proposed.

Improving the High-Temperature Energy Storage Performance of Epoxy Films: Moderately Reducing Unsaturation for Extremely High Efficiency.

The rapid development of renewable energy systems, electric vehicles, and pulsed equipment requires energy storage media to have a high energy storage density and efficiency in a wide temperature range. The state-of-the-art biaxially oriented polypropylene (BOPP) film is insufficient to meet the growing demand for energy storage devices due to its low energy storage density and working temperature, which make it a research hotspot for developing dielectric energy storage materials. In this manuscript, based on the epoxy materials that have been shown as a potential energy storage medium, we aim to reduce the influence of the benzene ring delocalization structure on the energy storage losses and enhance the efficiency by gradually replacing them with cyclohexane structures to adjust the segment unsaturation of epoxy materials. The results show that by partially reducing the unsaturation of the curing agent, the epoxy material achieves an excellent high-temperature energy storage density of 2.21 J/cm3 at 150 °C and 300 MV/m while maintaining an extremely high energy storage efficiency of 99.2%. Leakage current density and high-voltage dielectric spectroscopy tests confirm that a moderate reduction of the segment unsaturation of epoxy materials can greatly inhibit polarization loss at high temperatures, which may explain their high energy storage efficiency.

Development of radio frequency feedthrough prototype with high voltage and high vacuum for the HEPS strip-line kicker

Strip-line kicker is a significant equipment in the on-axis injection scheme, adopted by the High Energy Photon Source (HEPS). The Radio Frequency (RF) feedthrough with high voltage and high vacuum is needed to connect strip-line kicker and fast high voltage pulser. This feedthrough needs to meet specific requirements, including electrical power transmission, high voltage capability, ultrahigh vacuum sealing, broadband performance, radiation resistance, and the ability to sustaining bake-out. The performance of the feedthrough directly impacts the quality of the beam deflection achieved by strip-line kicker. In this paper, the design of feedthrough and the development of two prototypes are presented, then RF cold test, helium leaking test, vacuum baking, and the high voltage test conducted on two prototypes are introduced. For improving radiation resistance, the design incorporates PEEK (Polyetheretherketone) as the insulation material. The RF cold test results demonstrate that the maximum reflected power is less than 8%, and the insertion loss is within 0.8 dB at 3 GHz. After subjecting the feedthrough to 48 h of baking at 200 °C, the vacuum leakage is measured to be lower than 3 × 10−12 Pa m3/s. In the high voltage test, the feedthrough prototype performs well, withstanding a peak amplitude of ±20 kV, a pulse bottom width of 4 ns, and a repetition frequency of 50 Hz.

Modeling of electrocatalytic hydrogen evolution via high voltage alkaline electrolyzer with different nano-electrocatalysts

An energy system based on water for creating hydrogen energy might be less globally restricted than one that uses the available fossil fuels today. Therefore, creating an efficient catalyst and electrolyzer system is necessary to effectively convert renewable energy into chemical energy (hydrogen). In this study, a model based on kinetic reaction rate parameters is proposed for estimating energy efficiency and energy conversion for hydrogen generation in a high-voltage alkaline electrolyzer. Three complementary models, including the thermal, electrochemical, and thermodynamic, are conducted to forecast the thermal time constant, overall thermal resistance, operating temperature, electrolyzer voltage, energy consumption, and energy loss. To ensure that they can operate directly with renewable energy sources, the modeling was expanded to incorporate hydrogen production at a voltage level of 6 V. The model's various parameters were computed using non-linear regression presented in Engineering Equation Solver (EES) utilizing experimental data gathered in a high-voltage alkaline test rig. From their precursors and coated on Ti substrates, nanoparticles of Ag, TiO2, and Ag + TiO2 are created as electrocatalysts for the production of hydrogen. In comparison with the bare Ti electrode, the results revealed that energy efficiencies of the Ag, TiO2, and Ag + TiO2 electrodes have increased by 23%, 28%, and 28%, respectively. The largest improvement in hydrogen energy conversion achieved with TiO2 electrodes over Ti electrodes was 84%. Thermodynamic-thermal models that were integrated showed that the coated electrodes decreased the thermal energy loss (TΔS) and useable energy (ΔG) simultaneously during the electrolysis process. The electrochemical model demonstrated a strong fit to the data from those experiments, indicating that the coated nanomaterials are the most important factor in increasing the electrolyzer energy efficiency-based production of hydrogen. The models presented in this research offered a practical method for increasing hydrogen energy production and energy conversion using nanomaterial to build effective electrolyzer devices. The models described in this study are appropriate for the dynamic simulation of renewable energy-hydrogen systems. As a result, these models are easily connected to economic theories that account for both financial and operation expenses.

Investigation of structure, thermal and dielectric study of Dy0.05Ba0.7Sr0.25TiO3/polystyrene nanocomposites

In the present study, Dy0.05Ba0.7Sr0.25TiO3 (Dy-BST) nanoparticles were prepared using the conventional solid-state reaction technique. Different volume fractions of Dy-BST (0, 5, 10, 15 & 20) were immersed in the polystyrene (PS) matrix, forming PS/Dy-BST nanocomposites, then their crystal structure, morphology, topography, thermal properties, electrical properties, breakdown voltage, and energy storage were investigated. X-ray diffraction (XRD) validates the cubic phase of Dy-BST nanoparticles incorporated in PS/Dy-BST nanocomposites. The size of Dy-BST nanoparticles was in the range (8–18 nm) using HRTEM. Incorporating Dy-BST NPs into the polymer matrix improved the thermal stability and limited the thermal degradation of the nanocomposite. The loading of Dy-BST in PS has a positive effect on dielectric properties and breakdown strength. The permittivity (ε′) enhanced from 2 to 10 at a constant frequency of 105 Hz while a relatively high loss (tanδ) decreased from 0.0015 to 0.0011 with the increase of Dy-BST content in the PS matrix. Finally, dielectric strengths of PS/Dy-BST nanocomposites were evaluated using high voltage testing; then their corresponding energy densities were obtained. The energy density increased to 133% at a 10 vol.% loading of Dy-BST compared to pure polystyrene.

Device for the Automatic Detection of Fault Locations during High-Voltage Insulation Testing of Power Cable Lines of Electric Power Systems

Device for the Automatic Detection of Fault Locations during High-Voltage Insulation Testing of Power Cable Lines of Electric Power Systems

A Compact High-Stability Nanosecond Pulse Test System Using Corona-Stabilized Switch and Coaxial Resistance Divider

Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated. The influence of the action performance of the steepening gap on the characteristics of output nanosecond pulse was analyzed. The nanosecond pulse test system was established through the structural design of the nanosecond pulse-generating circuit, the development of a high-performance corona-stabilized switch, and the measurement of a fast-response resistance divider made of metal oxide thin-film resistors. The nanosecond pulse test system has the capability to output a double exponential nanosecond pulse voltages in the amplitude range of 10–60 kV with a rise time of 2.3 ± 0.5 ns and a half-peak time of 23 ± 5 ns. In addition, the output pulse voltage has a high consistency and stability in the full amplitude range. The maximum relative standard deviation of the peak value is 1.517%, and the relative standard uncertainty is less than 5‰.

Advanced Power Cycling Test Integrated With Voltage, Current, Temperature, and Humidity Stress

In this article, an advanced power cycling test with high voltage, large current, high temperature, and high humidity stress is proposed to get closer to the actual working conditions of power electronics in the accelerated aging test. The proposed test, integrated with High-Voltage High Humidity High Temperature Reverse Bias Test (HV-H3TRB) and standard DC Power Cycling Test (PCT), achieves precise measurement at the microsecond, millivolt, and microampere accuracy. A 6-kV/750-A prototype is built to verify the feasibility and effectiveness, and the noise mitigation method for measurement under high voltage is analyzed. The proposed test was carried out on the full-bridge power modules for electric vehicles, and the lifetime exhibits lower than the standard PCT. The root cause is the increment of thermal resistance at an early stage due to moisture invasion, which results in a failure mode change. Finally, the electrochemical corrosion signs induced by sulfur/carbon under voltage, temperature, and humidity stress are also revealed by optical inspection and Scanning Electron Microscope (SEM).