Wet conductor surfaces and the onset of corona discharges

Li, Q.; Rowland, S. M.

doi:10.1109/ceidp.2015.7352076

Cited by 6 publications

(5 citation statements)

References 19 publications

(22 reference statements)

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“…This counterintuitive result arises because of the phase lag between applied voltage and the resulting vibration. Without consideration of the phase relationship, the maximum field enhancement resulting from a conically extended droplet might otherwise be expected to have a field 1.3 times higher than its natural shape [7].…”

Section: Discussionmentioning

confidence: 99%

“…The distribution is plotted in Figure 2b [7]. It is observed that:  the average droplet size is larger for a more hydrophilic surface (1µl at 104°, 5 µl at 75°, and 7 µl at 63°)  the standard deviations for surfaces with different hydrophobicity are: 0.92 µl, 3.21 µl and 2.84 µl for contact angles of 104°, 75° and 63° respectively.…”

Section: Droplet Formation On Conductor Surfacesmentioning

confidence: 94%

“…These were subjected to the same wetting condition (a continuous fine mist spray) until fully wetted. A photograph of a single short length of conductor treated in this way is shown in Figure 2a [7].…”

Section: Droplet Formation On Conductor Surfacesmentioning

confidence: 99%

“…Subsequent experiments . Measured droplet size distribution, with associated box and whisker plot and fitted normal distributions [7].…”

Section: Literature Reviewmentioning

confidence: 99%

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The Impact of Water Droplet Vibration on Corona Inception on Conductors Under 50 Hz AC Fields

Rowland

Dupere

et al. 2018

IEEE Trans. Power Delivery

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Abstract--The relationship between the size of water droplets on the surface of AC high voltage conductors, their vibration and corona onset is investigated. Measurements have been carried out on individual droplets in high voltage experiments, including high speed photography, and discharge inception measurements. These have been correlated with acoustic emission from larger arrays of droplets on overhead transmission line conductors. A numerical model based on the finite element method has also been developed to simulate the vibration of the droplet enabling evaluation of the electric field and the characteristics of the droplet vibration. It is shown that the size of water droplet is critical in its mechanical response to the field and that corona does not necessarily occur when the droplet is deformed into its most conical state as is the case under DC fields. For larger droplets the phase shift between field and droplet vibration results in the maximum field occurring when the droplet is in a 'flattened' profile rather than when it is 'pointed'. The phase relationship between the droplet vibration and the electric field thus controls the onset of corona. It is argued that conductors which facilitate the development of small, uniform, stable droplets on their surface are the cause of abnormally high levels of low-frequency audible noise sometimes observed by transmission utilities. Moreover the narrow resonant response of the droplet may lead to a difference in acoustic emissions experienced between power utilities with 50 Hz and 60 Hz system frequencies.

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Section: Discussionmentioning

confidence: 99%

Section: Droplet Formation On Conductor Surfacesmentioning

confidence: 94%

Section: Droplet Formation On Conductor Surfacesmentioning

confidence: 99%

“…Subsequent experiments . Measured droplet size distribution, with associated box and whisker plot and fitted normal distributions [7].…”

Section: Literature Reviewmentioning

confidence: 99%

See 2 more Smart Citations

The Impact of Water Droplet Vibration on Corona Inception on Conductors Under 50 Hz AC Fields

Rowland

Dupere

et al. 2018

IEEE Trans. Power Delivery

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“…The deformation and vibration modes of the water droplet depend on a number of factors. The factors include the magnitude of the applied field, the surface tension, droplet size (volume) and the water density of the water droplet [13,20,21]. Additionally, the actual insulator surface has a non-uniform electric field distribution.…”

Section: Creepage Phenomenon On the Insulator Surfacementioning

confidence: 99%

The Dynamic Behaviour of Multi-Phase Flow on a Polymeric Surface with Various Hydrophobicity and Electric Field Strength

Liu

et al. 2022

Polymers

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The dynamic behaviour of rain droplets on the insulator surface is a key measure to its reliability and performance. This is due to the fact that the presence and motion of rain droplets cause intensive discharge activities, such as corona and low current arcing, which accelerate the ageing process and flashovers. This article aims to investigate and characterize the movement of a rain droplet placed on an inclined insulator surface subject to an intensive electric field. The rain droplets’ movement on hydrophobic surfaces in the absence of an electric field is investigated. A high speed camera is used to capture the footage and finite element method (FEM) is used to simulate the multi-physics phenomenon on two polymeric surfaces, namely, silicon rubber (SiR) and PTFE (polytetrafluoroethylene). A ‘creepage’ motion was observed. The inception of motion and the movement speed are analysed in correlation with various surface conditions. Models are established to estimate the moisture and potential discharge characteristics on the inclined polymeric surfaces. They are further utilized to analyse the actual insulators subject to wet conditions.

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Dynamic characteristics of corona discharge generated under rainfall condition on AC charged conductors

Xu¹,

Zhang²,

Wang³

et al. 2017

J. Phys. D: Appl. Phys.

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By synchronous measurement of corona current and the water droplet deformation process on a conductor surface, different types of corona discharge are visualized when AC voltage is applied on a line-ground electrode system. The corona characteristics are closely related to the applied voltage and water supply rate. With the increase of AC voltage, the positive Taylor cone discharge firstly appears and then disappears, replaced by the dripping and crashing discharge. Furthermore, the number of pulses in each pulse train increases with the increase of applied voltage. The mechanism of the transfer from the positive Taylor cone discharge to the dripping and crashing discharge is found to be related to the oscillation process of the water droplet. The water supply rate also has a great influence on the characteristics of corona currents. The number of positive pulse trains increases linearly when the water supply rate gets larger, leading to a higher audible noise and radio interference level from the AC corona, which is quite different from that of the DC corona. The difference between the AC and DC coronas under rainfall conditions is analyzed finally.

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Wet conductor surfaces and the onset of corona discharges

Cited by 6 publications

References 19 publications

The Impact of Water Droplet Vibration on Corona Inception on Conductors Under 50 Hz AC Fields

The Impact of Water Droplet Vibration on Corona Inception on Conductors Under 50 Hz AC Fields

The Dynamic Behaviour of Multi-Phase Flow on a Polymeric Surface with Various Hydrophobicity and Electric Field Strength

Dynamic characteristics of corona discharge generated under rainfall condition on AC charged conductors

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