Ion current measurements in SF&lt;inf&gt;6&lt;/inf&gt; and vacuum under high voltage DC application

Teppati, Valeria; Simka, Philipp

doi:10.1109/icepe-st.2017.8188908

Cited by 3 publications

(5 citation statements)

References 16 publications

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“…From the macroscopic perspective, the operating field strength is far below the conditions required to cause charge multiplication by impact ionization or field emission at the interfaces. However, the ion current measurements conducted in the technical fields using rough metal electrodes [16][17][18] or model spacers downscaled from gas-insulated equipment [3,11] indicated charge-generation processes that cannot be explained by ion-pair generation from natural ionization of gas. Because of lack of spatially resolved information and the revealed field-dependent characteristic, the currents are mainly attributed to the charge generation from the interfaces and modeled using homogeneous current sources [6].…”

Section: Discussionmentioning

confidence: 99%

Microscopic charge provision at interfaces of gas-insulated (HVDC/HVAC) systems

Tschentscher

Franck

2018

IEEE Trans. Dielect. Electr. Insul.

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Charge generation at the interfaces of gas-insulated switchgear or gas-insulated lines is mostly studied from a macroscopic point of view. Integral current measurements are a common method to determine the average inception field strengths and intensities of micro discharges. However, because of the lack of spatial resolution and measurement sensitivity, these experiments do not provide deeper insights on the microscopic processes. By applying surface potential measurement techniques, studying the charge generation of single interface protrusions and drawing conclusions relative to their spatial distribution have become possible. This paper presents a spatially resolved analysis of charge-generation processes at rough aluminum electrodes and insulating interfaces. The results reveal a highly inhomogeneous charge generation at the interfaces even for electric fields below 6 kV/mm. Analyzing the charge generation from a macroscopic perspective has been demonstrated to possibly underestimate the local charge generation by up to three orders of magnitude. Using sulfur hexafluoride (SF6) as the insulation gas at 0.45 MPa and Al2O3-filled epoxy resin insulators, the inception field strength for charge generation at the insulating interface is measured to be 3 kV/mm. For a technical insulation system that includes both a rough aluminum electrode and an insulating interface, significant discharge intensities are observed at a 5-kV/mm electric field. From these results, micro discharges are expected to be highly relevant for dimensioning of gas-insulated devices.

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Section: Discussionmentioning

confidence: 99%

Microscopic charge provision at interfaces of gas-insulated (HVDC/HVAC) systems

Tschentscher

Franck

2018

IEEE Trans. Dielect. Electr. Insul.

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“…The work presented in this contribution addresses this question using a purely empirical approach. Challenging the explanatory approaches of enhanced ion currents measured by other researchers for the increased humidity [4, 11, 12, 26], we distinguished the low‐field conduction phenomena from the microdischarge activities at the interfaces – for more details on the different conduction/charging regimes of HVDC spacers see [27] – to provide process‐related answers to the questions that remained.…”

Section: Discussionmentioning

confidence: 99%

“…In recent years, numerous publications have discussed the influence of humidity on the ion currents through gaseous insulation mainly using coaxial field arrangements in the dimensions of gas‐insulated HV busbars [4, 11, 12, 26]. To obtain an overview of the underlying processes, the researchers discussed the currents as a function of the gas pressure, relative humidity, and electrode roughness.…”

Section: Discussionmentioning

confidence: 99%

“…Supporting the assumption that H 2 O influences the formation of ion species in gas‐insulated devices, recent studies revealed a strong influence of humidity on the conduction current through SF 6 ‐insulation. The ion currents were measured at relative humidity greater than 10% RH at 20°C, which corresponds to ∼500 ppm v at 0.45 MPa [4, 11, 12]. However, the applicability of these findings to practical conditions, where gas‐insulated high‐voltage (HV) devices are exposed to under operation, is still questionable.…”

Section: Introductionmentioning

confidence: 99%

“…The specifications of GIS manufactures are usually lower than those prescribed by IEC, e.g. <13% RH at 0.45 MPa SF 6 [12].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of humidity on conduction processes in gas‐insulated devices

2020

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Humidity has been considered as one of the main influencing factors that determine the conduction processes and electric strength of gas-insulated systems. Whereas in the past, various studies focused on the change in the partial discharge inception voltages, breakdown strength of homogeneous and inhomogeneous field arrangements, and insulator flashover voltage, recent studies have investigated the changes in ion currents measured through different gas gaps. In the framework of this contribution, a highly precise humidity control circuit has been developed to analyse the significance of humidity in the range from −25 to −5°C frost-point, which is fully applicable to operating gas-insulated devices. Using sulphur hexafluoride (SF 6 ) as the insulation gas at 0.45 MPa, Al 2 O 3 -filled epoxy resin insulators, and technically rough electrodes, the humidity was found to significantly influence the intensity of microdischarges at interfaces. Charge generation from microdischarges at the interfaces substantially increased with increasing humidity. For an electric field of 5 kV/mm that were applicable to the dimensioning of gas-insulated devices, humidity strongly influences the charge provision from technically rough interfaces and potentially contributes to the surface-charge accumulation at insulator surfaces. On the other hand, for low-field conduction phenomena, no increase in the ion currents from natural ionisation or electrophoretic conduction was observed. For the investigated range of parameters, humidity is expected to be highly relevant for the design of gas-insulated devices.

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Simulation on Solid-Gas Interface Charge Accumulation Characteristics Under Repetitive Impulse Voltage

et al. 2022

2022 IEEE International Conference on High Voltage Engineering and Applications (ICHVE)

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Ion current measurements in SF<inf>6</inf> and vacuum under high voltage DC application

Cited by 3 publications

References 16 publications

Microscopic charge provision at interfaces of gas-insulated (HVDC/HVAC) systems

Microscopic charge provision at interfaces of gas-insulated (HVDC/HVAC) systems

Influence of humidity on conduction processes in gas‐insulated devices

Simulation on Solid-Gas Interface Charge Accumulation Characteristics Under Repetitive Impulse Voltage

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