High Voltage Impulse Generator Research Articles

An Experimental Study of Electromagnetic Field Propagation Due to Lightning Upward Leaders and Its Probability on Different Small-Scale Structures

In this paper, upward leader initiation and the probability of lightning flashes on different air terminal were analyzed in detail. With the growing global warming, lightning flash density has increased abruptly, especially in tropical countries. Upward leaders are the critical elements to be considered for defining comprehensive protective measures against lightning during thunderstorms. This article presents the lightning flashover phenomenon on scaled buildings with installed lightning rods. Moreover, the electric field and initialization of upward leaders from Lightning Air Terminals (LATs) were analyzed in detail using Ansys Maxwell as a simulation tool. For the experimental work, a high-voltage impulse generator was used. The air gap between the lightning rods and the top electrode was kept constant in all scaled structures. The purpose of using an identical air gap was to study the upward leader and its electric field for all structures. The effects of the upward leaders on the electric field plots are explained in detail and allowed the determination of the electric field’s intensity around each air terminal for the provided air gap between the tip of the rod and the top electrode. A low-cost lightning protection system was taken into account, as the economic crisis is worsening with time. A Franklin rod was used as the primary protection device for the initiation of the upward streamer. The experimental results were obtained in Malaysian weather conditions based on standard values of temperature and pressure. The study presented in this article shows that based on the experimental work, field plots were obtained for both the air insulation scenario and the condition when the upward leader was incepted. The simulation results showed a firm agreement with the measured values. Similarly, by upward leader inception, the strikes could be predicted accurately on every installed air terminal.

Nanosecond-scale impulse generator for biomedical applications of atmospheric-pressure plasma technology.

This study proposes an improved high-voltage fast impulse generator based on an inductive energy storage system with a 4kV static induction thyristor. Nanosecond-scale impulses with pulse widths below 100ns and a peak voltage of up to 15kV can be generated by modifying the high-voltage transformer in the circuit and tuning the circuit capacitor. The resulting device is highly stable and can perform continuously if the discharge parameters are chosen within the recommended range. A plasma jet was operated using the generator at low temperature (below 37 °C). Together with its high stability and potential for continuous operation, the proposed generator offers promise for use in biomedical and agricultural applications. Furthermore, the nanosecond-scale high-voltage impulses produced by the generator enable it to achieve an electron density in the plasma one order of magnitude higher than the commercially available radio frequency plasma jet analog. We also show how to reduce the total cost of the generator.

Usage of high voltage impulse generator to research the process of electropulse destruction of locust larvae in the soil

In accordance with announced technology, a laboratory research complex is needed for researching the influence of electropulse effects on locust larvae (capsules) and identification of the processing modes and construction design required to cause their irreversible (fatal) damage. In this regard, a schematic diagram of a laboratory research complex for electropulse processing has been developed and its structure has been determined. A separate question concerned a source of high voltage and a shaper of high-voltage impulses. A special design of a high-voltage impulse generator has been developed. This design can produce impact impulses of various durations - the impulse duration depends on the capacitive storage; with maximum amplitude of 16 kV and current per impulse of up to 400 A. The generator uses a capacitive storage discharge through a thyratron controlled by a microcontroller to the load. The proposed high-voltage impulse generator is necessary for researching the effect of electropulse high-voltage technology on the irreversible damage of locust larvae located in the soil layer, and for the experimental identification of the operating modes of the electrical part of the designed electrotechnological system, which allows for destruction of locust capsules directly in the field. The designed high-voltage generator was tested in operational mode when working with a load, which was the soil volume placed between the electrodes in the working chamber. The shape of the operational impulse and its parameters comply with predefined characteristics for electropulse cultivation of soil massif with locust larvae (capsules). After the tests, minor structural adjustments were made, and the generator itself was prepared for experimental studies in the laboratory.

Substantiation of criteria and methods for estimating efficiency of the electric impulse process of plant material

One of the most effective ways to prepare for extracting or removing intracellular fluid from plant material is its electric impulse treatment at initial processing stage before squeezing juice, dehydrating raw materials, drying materials, etc. As the parameters and modes that determine this process can be identified only experimentally, a device including a high-voltage impulse generator was designed. Plant tissue damage degree was assessed by changing resistance and phase shift. Intensive juice extraction was observed when high-voltage impulses in the amount of up to 100 units were supplied to plant material. With continued processing and increase in the number of impact impulses, the intensity of juice yield decreased, and the expended energy was spent on heating the plant material. The evaluation method based on quantitative analysis of pulse shape of flowing measuring current is proposed. The designed digital control device allows confirming the dependence of measured electrophysical parameters on changes occurring in plant material caused by electric impulse processing. The designed algorithm can be used as the basis of automatic control system operation for electroimpulse processing of plant materials before pressing.

Reconfiguration of 3 MV Marx Generator into a Modern High Efficiency System

High voltage impulse generators are intended to last for long periods of time. Upon reaching the end of their technical lifetime, decisions concerning decommissioning, replacement, refurbishment or upgrading are needed. A new generator is a considerable investment. Significant reductions in material and labor costs can be made by repurposing still functional elements of the existing generator and redesigning the circuit for higher efficiency requiring fewer components. This paper describes the process of refurbishing the Mississippi State University (MSU) High Voltage Laboratory 3 MV, 56 kJ impulse generator originally built in 1962 into a modern digital impulse generator system.

Cold pressing of ferroelectric-ferromagnetic layered composites for nonlinear forming lines of high-voltage impulse generators

Cold pressing of ferroelectric-ferromagnetic layered composites for nonlinear forming lines of high-voltage impulse generators

Design and Fabrication of a High Voltage Lightning Impulse Generator

This paper reports 10 kV to 100 kV high voltage impulse generator. Generation of variable outputs impulse generator can be designed by combination of flyback transformer and Marx generator which can produce different high voltages. It is a portable device for field. The experimental final results have been taken by using spark gap measurements and voltage divider technique. This high voltage lightning impulse generator produces standard T1/T2 waveshape impulses. The testing of protection devices such as SPD (surge protection device) is extremely important to find out whether these devices can operate in standard conditions or not. That’s why the high voltage lightning impulse generator is developed for such testing. Similarly, our research work consists of modeling and practical design of a 100 kV impulse generator.

고전압 임펄스에 의한 스케일 제어

본 연구에서는 산업용수의 처리 및 운용 과정에서 중요한 문제점으로 지목되고 있는 탄산칼슘에 의한 스케일 형성을 제어하기 위해 고전압 임펄스 (High Voltage Impulse, HVI) 기술의 활용 가능성을 평가하고자 하였다. 전원부, 고전압발생부, 축전기, 스위치 및 임펄스발생기로 구성된 HVI를 제작하여 17kV의 고전압 펄스를 생성시켰다. 반응조에 <TEX>$Ca^{2+}$</TEX>을 포함하고 있는 인공 시료를 투입한 후 HVI를 인가하였다. HVI 접촉시간 5분 후에는 <TEX>$Ca^{2+}$</TEX> 초기값의 3.0% 가량만 감소하였으나, 접촉시간 60분 후에는 약 13.7% 가량 감소하였다. HVI 인가로 인해 용액의 온도와 pH는 증가하였고 전기전도도는 탄산칼슘 석출로 인해 감소하는 것을 확인하였다. 칼슘 이온의 감소가 충분하지는 않았지만 전계의 세기 및 접촉시간에 따른 제거율에 간한 구체적인 정보가 얻어진다면, HVI 기술을 적용하여 <TEX>$Ca^{2+}$</TEX> 이온을 탄산칼슘으로 미리 석출시켜 제거하는 연수화 (softening) 공정이나 탈염 기술로 활용할 수 있는 가능성을 확인하였다. The aim of this study was to evaluate the feasibility of application of the high voltage impulse (HVI) technique to the control of scale formation by calcium carbonate, which is pointed out as an important issue in industrial water treatment. The HVI system consisted of the power supply, high voltage generator, capacitors, switch and impulse generator was designed and made in laboratory scale, which can make 17kV impulse. HVI was introduced to the reactor that was filled with synthetic water containing <TEX>$Ca^{2+}$</TEX>ion. The concentration of calcium ion decreased only 3.0% after 5 minutes of contact time. However, it decreased up to 13.7% after 60 minutes of HVI contact time. Temperature and pH increased but conductivity decreased due to precipitation of the calcium carbonate. Although the decrease in concentration of calcium ion was not sufficient, it was verified that the HVI technique could be applicable for the softening and desalting processes.

Lightning protection of wind turbine blades

The causes of lightning damages of wind turbine blades were clarified through lightning observation and experiments using a high-voltage impulse generator. Upward leaders and large energy of winter lightning, which is frequent along the coast of the sea of Japan, play an important role upon lightning damages of wind turbine blades. Lightning discharges may penetrate into the cavity of a blade without lightning receptors, resulting in serious damages, such as an destruction and falling of a blade. Although lightning receptors are totally useful for lightning protection of wind turbine blades, they are not perfect.

A rapid 2-MV impulse generator

A high-voltage nanosecond impulse generator was developed and tested in order to create electromagnetic impulses (EMIs) in a given area. Tests revealed the characteristics of the generator’s output impulse: the rise (at a level 0.1–0.9) is about 3.2 ns, the length is 27 ns at half-deflation, and the magnitude is 2 MV. The generator is used to test large-size equipment for tolerance to industrial EMIs.

Natural laminar-turbulent transition delay by dielectric barrier discharge

The use dielectric barrier discharge for the delay of laminar turbulent transition excited by natural flow disturbances in a quiet wind-tunnel was investigated experimentally. Optimal electrodes location and the operational regime of high-voltage impulse generator provided maximal downstream shift of transition location were found. It was demonstrated that the 10% increase of the laminar part of boundary layer can be obtained using barrier discharge with the cross-flow electrodes. This gives up to 20% friction drag reduction.

Portable High Voltage Impulse Generator

This paper presents a portable high voltage impulse generator which was designed and built with insulation up to 20 kV. This design was based on previous work in which simulation software for standard waves was developed. Commercial components and low-cost components were used in this work; however, these particular elements are not generally used for high voltage applications. The impulse generators used in industry and laboratories are usually expensive; they are built to with stand extra high voltage and they are big, making them impossible to transport. The proposed generator is portable, thereby allowing tests to be made on devices that cannot be moved from their location. The results obtained with the proposed impulse generator were satisfactory in terms of time and wave forms compared to other commercial impulse generators and the standard impulse wave simulator.

Cascoded HBT pair: A new method of generating subnanosecond high‐voltage impulses

AbstractIn this letter, a fully integrated subnanosecond high‐voltage impulse generator using 2‐μm GaAs HBT process is presented. The core circuit consists of a cascoded HBT pair with an inductor and it works on two principles: a faster transition can be obtained from a digital logic input into the HBT and a differentiation of the very fast transition current using the inductor to generate a large voltage at the output. Measurement results show the generated impulses have a tunable peak voltage between 0.5 and 3.2 V with a full‐width‐half‐maximum (FWHM) of 100 ps. The impulse generator is biased from a 3.3 V battery supply and consumes 15 mW at 1 MHz pulse repetition rate (PRF). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1683–1685, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25295

토양의 이온화영역에서 소규모 접지전극의 과도접지임피던스 특성 분석

This paper presents measurement results of transient impedance for small-sized ground electrodes in a discharge region of soil. For a realistic analysis of ionization characteristics near the ground electrode, three types of ground rod installed outdoors and high voltage impulse generator were used for injecting test current. From the analysis of response voltage and current flowing ground electrode to earth, it is verified that the ionization near the ground electrode contributes to reduction of ground impedance and limits the ground potential rise effectively in high resistivity soil. As a threshold electric field density for ionization is small in low resistivity soil, the shape of ground electrode rarely contributes to the transient impedance. And, from the experiment result with shape of ground electrode, the rod with needles is more effective to reduce the transient impedance than the plate electrode in the voltage range including with ionization regions of soil.

Low energy single stage high voltage impulse generator

High voltage (HV) impulse generators are employed widely for testing of HV apparatus, as such tests are codified in a range of standards. As a result, insulation properties under impulse waveforms are of interest in the design of HV apparatus. This creates a need for very low energy laboratory impulse generators which can be used to test laboratory scale samples, often in conjunction with sensitive electronic instrumentation to measure sample dielectric properties. Since the sample is often the only isolation between the impulse generator and the electronics, failure of the sample will result in exposure of the electronics to the energy stored in the generator. This paper provides design details for a very low energy (/spl sim/1 nF storage), single-stage impulse generator which provides clean double exponential waveforms.

Radiated interference from a high voltage impulse generator

High voltage switching operations radiate large electromagnetic fields. These cause interference to sensitive electronic equipment. For example, the environment of most concern are those of high voltage substations and high voltage research laboratories. This paper evaluates electric and magnetic field measurements obtained during the breakdown of an SF/sub 6/ gas gap when a 4/400 /spl mu/s pulse was applied from a high-voltage impulse generator. Building upon previous work concerning initial results in terms of the E-dot and H-dot measurements, this paper also includes the evaluation of the E and H field magnitudes to determine the extent of equipment interference within the vicinity of switching/pulse operations. In addition, these laboratory results were extrapolated to allow comparisons to be made with results from previous studies investigating switching operations within a substation environment. The implications regarding EMC immunity standards and the level of interference is discussed.

Reduced-order modelling of a high-voltage oscillatory impulse generator

The design of high-voltage equipment encompasses the study of oscillatory surges caused by transients such as those produced by switching. By obtaining a model, the response of which reconstructs that observed in the actual system, simulation studies and critical tests can be carried out on the model rather than on the equipment itself. In this paper, methods for the construction of simplified models are described and it is shown how the use of a complex model does not necessarily result in superior response pattern reconstruction.

A Digital Timing Unit for Impulse Generator Control

This paper describes the design and construction of an impulse generator control unit which uses the counting of predetermined numbers of 10 MHz pulses to fix precise time delays for the control of a high voltage impulse generator and its associated recording equipment. Facilities for point on wave firing control are also provided. Particular attention is paid to problems arising from the high noise levels likely to occur in the high voltage laboratory environment.

The time isolation high-voltage impulse generator

Lewis' high-voltage impulse generator is analyzed in greater detail, demonstrating that voltage between adjacent nodes can be equalized by proper selection of parasitic impedances. This permits improved TEM mode propagation to a matched load, with more faithful source waveform preservation.

Cable-fault location by impulse-current method

The paper presents a new approach to cable-fault location based on the use of high-voltage impulse generators. It is shown that, when an impulse generator is connected onto a faulty cable, the waveform of the generator output current can be used to determine the position of a fault. Several advantages are gained by the use of a linear coupler to provide the signal to the instrumentation, and it is shown that the signal also indicates whether or not an acoustic signal is being produced at the fault. The nonlinear characteristics of faults, which introduce errors and complications into most existing methods of fault location, are fully exploited with the new technique. Digital transient recorders are shown to have many advantages over the currently used methods of recording impulse waveforms. The information stored in the memory of a transient recorder can be easily transmitted to another location for interpretation by an experienced engineer. The more complex waveforms obtained on multibranched networks would be interpreted with the aid of a computer. It is suggested, that both the hardware and software being developed for cable-fault location purposes will also find application in the growing field of diagnostic testing.