scholarly journals Investigation of impact of DC component on breakdown characteristics for different electric fields under composite AC & DC voltage

High Voltage ◽  
2022 ◽  
Author(s):  
Mehmet Murat Ispirli ◽  
Özcan Kalenderli ◽  
Florian Seifert ◽  
Michael Rock ◽  
Bülent Oral
Keyword(s):  
Electric Fields ◽  
Dc Voltage ◽  
Dc Component

Study on Electric Field Characteristics of Converter Transformer on Valve Side Winding

2011 ◽  
Vol 130-134 ◽  
pp. 1413-1417
Author(s):  
You Hua Gao ◽  
Guo Wei Liu ◽  
Yan Bin Li ◽  
You Feng Gao
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
High Voltage ◽  
Electric Field Distribution ◽  
Influence Factors ◽  
Calculation Model ◽  
Dc Voltage ◽  
Voltage Polarity ◽  
Transient Electric Field

Numerical calculation model with compound insulation of transient electric field is given. The insulation is more prominent due to complication for voltage applied on valve side winding of the converter transformer. So the simplied structure for electric calculation on the valve side winding of the converter transformer is established. The electric field distribution characteristics on the valve side winding of the converter transformer is analyzed and electric fields in different resistivity and permittivity are calculated under AC high voltage, DC high voltage, AC superimposed DC voltage, polarity reversal voltage. The maximum electric field intensity is calculated and analyzed under kinds of high voltage. Some important influence factors for electric field distribution are also discussed in this paper.

scholarly journals External-Electric-Field-Enhanced Uniformity and Deposition Rate of a TiO2 Film Prepared by the Sparking Process

2018 ◽  
Vol 63 (6) ◽  
pp. 531 ◽  
Author(s):  
W. Thongpan ◽  
T. Kumpika ◽  
E. Kantarak ◽  
A. Panthawan ◽  
P. Pooseekheaw ◽  
...  
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Deposition Rate ◽  
Tio2 Films ◽  
Dc Voltage ◽  
External Electric Fields ◽  
Deposited Film ◽  
Field Area ◽  
Scanning Electron

We have used an external electric field to increase both the uniformity and deposition rate of TiO2 films. The experiment is carried out by sparking-off titanium wires with a high dc voltage of 1 kV (field Eint = 10 kV/cm) and a limited current of 3 mA. The external electric fields (Eext) of 3, 6, and 9 kV/cm were applied to the sparking system for 1–5 hours. The as-deposited film morphology was characterized by scanning electron microscopy. The results clearly show that the films are only deposited on the external electric field area. Furthermore, the deposition rate of the films increased from 40.7% to 77.8% in the presence of the external electric field of 9 kV/cm. The effects of an external electric field on both the deposition rate and uniformity of films are investigated and described.

scholarly journals Influence of the DC offset on the DFT-based frequency estimation for noised multifrequency signals in PV systems with a DSP processor

2018 ◽  
Vol 64 ◽  
pp. 06011
Author(s):  
Kania Dariusz ◽  
Borkowski Józef
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Frequency Estimation ◽  
Time Windows ◽  
Estimation Method ◽  
Digital Signal ◽  
Dc Voltage ◽  
Dc Offset ◽  
Pv Systems ◽  
Dc Component

Digital signal processing is present in many areas of industry and science. One of them is analyzing multifrequency signals, e.g. in photovoltaic systems. This paper focuses on the frequency estimation of pure signals and signals distorted by AWGN noise in the presence of a DC voltage offset. The used IpDFT estimation method is based on the FFT procedure, I class Rife-Vincent time windows and three points of the spectrum taken to calculations. Measurement time was limited only up to two cycles of a tested signal and the method is very accurate even below one cycle. Obtained results show that additional DC component negatively affect the accuracy. The paper can be very useful because it shows properties of the method in real measurement conditions for various values of parameters.

Tunneling Current in Thin Silicon Dioxide Films

1994 ◽  
Vol 342 ◽  
Author(s):  
Sufi Zafar ◽  
J. C. Poler ◽  
E. A. Irene ◽  
X. Xu ◽  
G. Haines ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Thermal Oxidation ◽  
Electric Fields ◽  
Tunneling Current ◽  
Chemical Vapor ◽  
Silicon Dioxide Films ◽  
Thin Silicon ◽  
Tunneling Currents ◽  
Dc Component ◽  
P Type

ABSTRACTTunneling currents through thin silicon dioxide films on p-type silicon are measured at electric fields greater than 5 MV/cm. At the onset of the Fowler-Nordheim tunneling, oscillations in the current are observed. These oscillations are used for characterizing oxide films grown by three different processes: rapid thermal chemical vapor deposition, rapid thermal oxidation and thermal oxidation. We have explored the correlation between the oscillatory tunneling currents and the breakdown fields, and find a low field dc component to correlate with the breakdown fields and obscure the oscillations.

Bubble Free High Efficiency Electroosmotic Pumps

2015 ◽  
Author(s):  
Mena E. Tawfik ◽  
Thomas E. Hansen ◽  
F. J. Diez
Keyword(s):  
Electric Fields ◽  
High Efficiency ◽  
Limiting Factor ◽  
Voltage Waveform ◽  
Gas Generation ◽  
Bubble Generation ◽  
Dc Voltage ◽  
Electroosmotic Pump ◽  
Pulsed Dc ◽  
Electroosmotic Pumps

In generating high electroosmotic flows for use in microfluidic pumps, a limiting factor is faradaic reactions which appear at high electric fields. These reactions lead to higher power consumption and bubble generation at the electrodes. We are proposing a novel technique that can limit and even prevent gas generation. This will extend the current range of operation of electroosmotic pumps. This is achieved by applying a unidirectional pulsed DC voltage waveform. The optimum pulse voltage waveform (OPW) tested is based on a theoretical model developed by the authors [1]. The power consumed and the efficiency of an electroosmotic pump under the pulsed DC voltage is measured experimentally and compared with the conventional bipolar rectangular voltage waveform (BRW). Results show an increase in the efficiency for the OPW when compared to the BRW. This increase in efficiency is obtained by preventing the reverse cycle in the BRW which flows against the pumping direction.

Ultra Fast Micropumping by Reaction Enhanced AC Electrothermal Effect

2009 ◽  
Author(s):  
Meng Lian ◽  
Jie Wu ◽  
Prachya Mruetusatorn
Keyword(s):  
Electric Fields ◽  
Electrode Array ◽  
Temperature Gradients ◽  
Dc Voltage ◽  
Ion Generation ◽  
Exciting Opportunity ◽  
Order Of Magnitude ◽  
Electric Potentials ◽  
Dc Bias ◽  
Conductivity Gradient

AC electrothermal effect generates temperature gradients in the fluids, consequently inducing free charges that move in electric fields, and produce microflows in microchannel. This paper reports dramatic improvements in flow rate over conventional ac electrokinetic micropumps by exploiting asymmetry in electric potentials over the electrodes. A micropump consisting of planar asymmetric electrode array was tested using AC signals with and without a DC bias. The pumping velocity is much faster with a DC voltage, in some cases by an order of magnitude, reaching 3.2 mm/sec linear velocities with only 9 Vrms. Our hypothesis attributes the increase of ACET force to the ion generation near electrode by reactions and the resulting high conductivity gradient. The discovery presents an exciting opportunity for microfluidics, and further improvement can be anticipated with some optimization.

Electric Trapping and Lysing of Cells in a Microchannel Constriction

2009 ◽  
Author(s):  
Christopher Church ◽  
Junjie Zhu ◽  
Guohui George Huang ◽  
Gaoyan Wang ◽  
Tzuen-Rong Jeremy Tzeng ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Concentration ◽  
Ac Electric Fields ◽  
Ac Electric Field ◽  
Electrical Lysis ◽  
Smooth Switching ◽  
Dc Component ◽  
High Electric Fields ◽  
Pressure Driven Flow

Cell lysis is a necessary step in the analysis of intracellular contents. It has been recently demonstrated in microfluidic devices using four methods: chemical lysis, mechanical lysis, thermal lysis, and electrical lysis [1]. The locally high electric fields needed for electrical lysis have been achieved using micro-electrodes and micro-constrictions for pulsed and continuous DC electric fields, respectively. However, since the two determining factors of electrical lysis are field strength and exposure time, opposing pressure-driven flow must often be used in pure DC lysis to reduce the velocity of the cells and to ensure the cells spend sufficient time in the high electric field region [1,2]. Using DC-biased AC fields can easily fulfill these requirements as only the DC component contributes to cell electrokinetic transport. Prior to lysis, cell concentration can be increased by trapping using dielectrophoresis (DEP), which may occur with either DC or DC-biased AC electric fields [3,4]. This operation is useful in cases where the cell supply is limited or when the cell concentration is too low in general. In this work, red blood cells are used to demonstrate the smooth switching between electrical lysing and trapping in a microchannel constriction. The transition between lysis and trapping is realized by tuning the DC component in a DC-biased AC electric field.

scholarly journals Effect of DC Electric Fields on Flame Spread Over Twin Electrical Wires

2019 ◽  
Author(s):  
Jeong Park ◽  
Sun Ho Park ◽  
Min Suk Cha ◽  
Suk Ho Chung
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Flame Spread ◽  
Wind Effect ◽  
Spread Rate ◽  
Dc Voltage ◽  
Positive Voltage ◽  
Transient Period ◽  
Dc Electric Field ◽  
Flame Behavior

Abstract The effect of DC electric field on the behaviors of spreading flame over polyethylene (PE)-insulated twin electrical wires was investigated by varying the wire gap (S) and voltage (VDC). The twin flame spreads with the same flame spread rate (FSR) independently when no electric field is applied. With an applied DC electric field, the twin flame interacts such that FSR, flame width, and the leaning direction of interacting twin flames vary appreciably. The spread rate for wire flame with negative voltage (SF–) was larger than that with positive voltage (SF+) during transient period and then the two became the same in a developed region (a quasi-steady spread). Such a flame behavior could be grouped into two: twin flame spread (regime I) and single flame spread (regime II) after the extinction of SF+. Each regime could be categorized into three sub-regimes depending on S and VDC. For small VDC, the flame leaned toward the burnt wire, reducing FSR. With further increasing VDC, FSR increased due to the ionic wind effect and then decreased via the mass loss of molten PE. These non-monotonic behavior of FSR with DC voltage can be attributed the behaviors of molten PE, exhibiting dripping, electrospray, and di-electrophoresis phenomena. For further increased voltage, the flames were extinguished by streamer generation and an electrical short occurred at excessive voltages.

scholarly journals Particle Imaging Velocimetry Measurement of Air Flow Between High Voltage Asymmetrical Electrodes

2020 ◽  
Vol 328 ◽  
pp. 05007
Author(s):  
Jiří Primas ◽  
Michal Malík ◽  
Petr Schovanec ◽  
Josef Novák ◽  
Pavel Pokorný ◽  
...  
Keyword(s):  
Electric Fields ◽  
Particle Image ◽  
Theoretical Description ◽  
Dc Voltage ◽  
Practical Applications ◽  
Image Velocimetry ◽  
Particle Imaging Velocimetry Measurement ◽  
Strong Electric Fields ◽  
The Many ◽  
Particle Imaging

This paper deals with the airflow generation phenomenon occurring on a system of strongly asymmetrical electrodes connected to high DC voltage. The main focus was to measure the airflow directly between the electrodes using Particle Image Velocimetry. The authors are well aware of the many difficulties presented by the task of measuring in the presence of strong electric fields and the paper also describes the means used to overcome these issues. The results of performed measurements are presented, their agreement with theoretical description of given phenomenon is discussed and several possible practical applications are proposed.

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