Measurement and Validation of Spark Length for Air Discharges of Electrostatic Generator

Taka, Yoshinori; Kawamata, Ken; Fujiwara, Osamu

doi:10.1541/ieejfms.135.259

Cited by 13 publications

(9 citation statements)

References 12 publications

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“…Next, to verify the measured waveforms in Figure 3, we compare them with theoretical values of electrostatic field before discharge. 13 These empirical formulas are: With V c = 0.6 kV, Equations (7) and (8) give 25 and 41 m, respectively; here we adopt = 30 m. Thus, predischarge electrostatic field produced by charged spheres can be calculated by Equation (1); distance dependence of this theoretical value is shown by red line in Figure 7. 13 These empirical formulas are: With V c = 0.6 kV, Equations (7) and (8) give 25 and 41 m, respectively; here we adopt = 30 m. Thus, predischarge electrostatic field produced by charged spheres can be calculated by Equation (1); distance dependence of this theoretical value is shown by red line in Figure 7.…”

Section: Electric Dipole and Electrostatic Fieldmentioning

confidence: 99%

Verification of Measurement Waveforms of Transient Electric Field caused by Micro-gap Spark using Optical Electric Field Probe

et al. 2018

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With the widespread use of wearable terminals, machine to machine (M2M) and internet of things (IoT) equipment, electrostatic discharge (ESD: Electrostatic Discharge) due to electrification of humans and objects can cause electromagnetic interference (EMI) inside these devices, which is called intra-EMC (Electromagnetic compatibility). This type of the EMI issue would be often derived from a steep transient electric near field generated by less than 1 kV spark discharges between micro-gaps. To clarify the characteristics of such electric near field, therefore, an optical electric field probe, which does not disturb any electromagnetic fields to be measured, has been used to measure the transient electric field caused by a micro-gap spark when charged metal spheres collide, while it is not fully understood whether or not the probe output precisely responds to the transient electric field in the vicinity of the discharge point. In this study, the measured waveforms of the above-mentioned electric field are verified by comparison with the electrostatic field theoretically derived from image charges and the transient electric field calculated from an image dipole charge model combining a spark resistance law. The result reveals that at a distance near the discharge point the optical field probe does not properly work due to the presence of the electrostatic field, whereas the transient electric field at a distance away from more than twice the diameter of metal spheres from the discharge point can be correctly measured because of sufficient attenuation of the electrostatic field component. K E Y W O R D Selectrostatic discharge, micro-gap discharge, optical electric field probe, transient electric field, verification Electron Comm Jpn. 2019;102:3-11.

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Section: Electric Dipole and Electrostatic Fieldmentioning

confidence: 99%

Verification of Measurement Waveforms of Transient Electric Field caused by Micro-gap Spark using Optical Electric Field Probe

et al. 2018

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“…In contrast, B type shows slower buildup and much lower peak as compared to contact discharge As regards air discharge, current is known to vary with approach speed, temperature, and humidity, even at same test voltage; for example, it was reported that buildup of discharge current becomes sharper and current peak increases, with higher approach speed or lower relative humidity [7,9]. On the other hand, it was shown experimentally that spark length tends to shorten with higher approach speed of electrodes in case of air discharge or discharge involving movement of charged electrodes [10,11]. In our measurements, discharges are conducted at same temperature and relative humidity, and at nearly same ESD approach speed.…”

Section: Measured Results and Discussionmentioning

confidence: 99%

“…In the diagram, and denote spark length (mean value ± standard deviation) averaged across 21 measured waveforms of air discharge in generators of A type and B type, respectively. Besides, • and vertical bars show values (mean value ± standard deviation) of spark length measured when a metal plate of 50 mm in diameter approached ESD generator at constant speed of 100 mm/s [10]. The solid line shows results calculated by empirical Paschen's law [10].…”

Section: Estimation Of Spark Length and Calibrationmentioning

confidence: 99%

“…Besides, • and vertical bars show values (mean value ± standard deviation) of spark length measured when a metal plate of 50 mm in diameter approached ESD generator at constant speed of 100 mm/s [10]. The solid line shows results calculated by empirical Paschen's law [10]. The figures in the diagram show peak variation coefficient in percentage terms (relative standard deviation: standard deviation/mean value).…”

Section: Estimation Of Spark Length and Calibrationmentioning

confidence: 99%

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Waveform Comparison and Difference Factors in Discharge Currents for Air Discharges from Different ESD Generators

Taka

Ishida²,

Fujiwara

2017

Electrical Engineering Japan

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SUMMARY Electrostatic discharge (ESD) generators must be calibrated for contact discharges with the current waveform specified in International Electro‐technical Commission (IEC)61000‐4‐2; however, there are no requirements in current waveforms due to their bad reproducibility for air discharges in the IEC standard. Nevertheless, the air discharge immunity testing is under obligation in the present standard. This implies that different ESD generators are likely to provide significantly different test results for air discharge testing. In this study, two types of different ESD generators were used to measure discharge currents both for contact and air discharges with respect to charge voltages from 2 kV to 8 kV under the same conditions of experimental environment. As a result, we confirmed that the measured waveforms were almost identical for contact discharges regardless of charge voltages, while we found that they are quite different for air discharges with the same approaching speed when the charge voltages are increased. The latter result is because the generator has different impedance characteristics deriving from its structure, and because the spark lengths from the generators with the same charge voltage are different. A formula for calculating the discharge current from an ESD generator through an ideal switch in lieu of a spark, which was previously derived by us, was also employed to obtain the current waveform peculiar to the generator, in order to reveal that the formula provides the different upper limit of air discharge current peaks according to the generator.

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“…Expression for breakdown voltage in Paschen's law is semi‐empirical, being dependent on electrode material and surface conditions; therefore, estimation accuracy must be taken into account. Besides, interelectrode distance is reported to depend on approach speed even at same voltage, which must be taken into account at a high speed.…”

Section: Discussionmentioning

confidence: 99%

Electrostatic energy dependence of intensity ratio between nitrogen spectral lines of monovalent ion and neutral atom in electrostatic spark discharge in air

Miura

2018

Electrical Engineering Japan

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For the development of a practical method to estimate the energy of electrostatic air discharge without electrical measurements, the dependence of spectral characteristics of light emission from the spark discharge on electrostatic energy was investigated. It was found that the relative light intensity emitted from a monovalent positive ion of nitrogen (N II) to a nitrogen atom (N I) increased with the electrostatic energy from 0.02 mJ to 20 mJ. In the same electrostatic energy, the intensity ratio, that is the intensity of N II divided by that of N I, increased with the decrease of applied voltage. This implied that the ratio becomes large when increasing the electrostatic energy divided by the breakdown gap length. Separating the measurements into similar voltage groups, the relation between the ratio and the electrostatic energy became clear.

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Measurement and Validation of Spark Length for Air Discharges of Electrostatic Generator

Cited by 13 publications

References 12 publications

Verification of Measurement Waveforms of Transient Electric Field caused by Micro-gap Spark using Optical Electric Field Probe

Verification of Measurement Waveforms of Transient Electric Field caused by Micro-gap Spark using Optical Electric Field Probe

Waveform Comparison and Difference Factors in Discharge Currents for Air Discharges from Different ESD Generators

Electrostatic energy dependence of intensity ratio between nitrogen spectral lines of monovalent ion and neutral atom in electrostatic spark discharge in air

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