Creeping discharges propagating on natural ester oils/pressboard interface under AC and lightning impulse voltages

Reffas, Abderrahim; Moulai, H.; Béroual, Abderrahmane

doi:10.1109/tdei.2018.007217

Cited by 21 publications

(3 citation statements)

References 19 publications

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“…His work shows that discharges in vegetable oil have extensions whose values are 60% higher than those in MO. A number of results in this direction can be found in the literature 29 , 30 . Even at high voltage and temperature, the results obtained with COME and PKOME show increments that are much lower than those found in the literature at room temperature.…”

Section: Discussionmentioning

confidence: 98%

Combined effect of lightning impulse voltage and temperature stress on the propagation of creeping discharge of oil-impregnated paper

Jiosseu,

Foumi Nkwengwa,

Mengata Mengounou

et al. 2024

Sci Rep

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This article presents the results of an experiment designed to study the impact of temperature on the characteristic parameters of creeping discharges. The insulating interfaces consist of a thermally enhanced cellulose surface immersed in mineral oil, palm kernel oil methyl ester (PKOME) and castor oil methyl ester (COME). The study was carried out under a standard negative lightning impulse voltage (1.2/50 μs). The article also presents the complete algorithms for calculating the maximum extension of the discharges, the ionisation rate and the charge produced by them. The results of the study show that temperature favors the propagation of discharges and the ionisation rate. It was observed that liquids with a higher dielectric constant and high electrical conductivity were more exposed to the impact of temperature. The results show ionisation increments of 0.973%/°C, 1.093%/°C and 1.076%/°C in mineral oil (MO), COME and PKOME respectively. The maximum extension of the discharges shows a linear evolution with the applied voltage and temperature but a non-linear increment with the temperature. As for the charge produced, it shows a constant increment with temperature and voltage in each liquid. These values are (5.839%/°C, 1.977%/kV), (6.047%/°C, 2.082%/kV) and (6.177%/°C, 2.113%/kV) respectively in MO, COME and PKOME.

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Section: Discussionmentioning

confidence: 98%

Combined effect of lightning impulse voltage and temperature stress on the propagation of creeping discharge of oil-impregnated paper

Jiosseu,

Foumi Nkwengwa,

Mengata Mengounou

et al. 2024

Sci Rep

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“…is of increasing interest in the power industry. Natural and synthetic ester fluids are polar, as opposed to traditional mineral oils [6]. This reason allows the ester liquids to hold much higher water; this makes them hygroscopic.…”

Section: Introductionmentioning

confidence: 99%

Pre-Breakdown and Breakdown Behavior of Synthetic and Natural Ester Liquids under AC Stress

et al. 2021

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In the last decades, a large focus is being placed on the sustainability and safety of the power transformer spectrum. Ester liquids, which have interesting properties such as high fire point and biodegradability, are gaining needed attraction. Since in-service condition, thermal aging deteriorates the physicochemical and electrical properties of liquid dielectrics, it is important to study their long-term behavior. In this contribution, the pre-breakdown and breakdown behavior of ester fluids (synthetic and natural) under AC stress are investigated. Important characteristics, such as partial discharge pre-inception voltage, partial discharge inception voltage, breakdown voltage, average streamer velocity, and inception electric field, were assessed. The influence of the radius of curvature (of high voltage needle electrode) as well as the thermal degradation of typical ester liquids are also discussed. Mineral oil was also included in the tests loop as a benchmark for comparative purposes. It is found that the pre-inception voltage of ester liquids was, in most cases, higher than that of mineral oil. For a given radius of curvature, the streamer inception and breakdown voltages decreased with thermal aging. During the streamer initiation, the electric field at the electrode tip decreased with the increase in the radius of curvature. The velocity of the streamers seems to increase with the decrease in the radius of curvature. The period of vulnerability, the so-called “delay time”, seems to be independent of the aging or the radius of curvature for a given condition of the liquid.

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“…• As power transformers are often electrically and sometimes physically connected with gas-insulated substations (GIS) and generators, abnormal signals detected in the power transformer may be caused by other equipment, such as switch operation impulse intrude into power transformer [9], [14]. These facts mean that an isolated and specific monitoring system utilizing one symptom may provide a false alarm or missed alarm, in one hand.…”

Section: Introductionmentioning

confidence: 99%

A Novel Power Transformer Condition Monitoring System Based on Wide-Band Measurement of Core Earth Signals and Correlation Analysis With Multi-Source Data

Pang²,

Dong

et al. 2019

IEEE Access

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On-line condition monitoring and real-time fault detection are essential to protect power transformers from unscheduled outage of services. The core earth signals (CES) are valuable for fault detection and diagnosis of power transformers, as they are related to multiple transformer defects and faults, such as core multi-point earthing fault and core deep saturation. Moreover, the CES also contain valuable information of transient impulses intruded into power transformers such as very fast transient overvoltage (VFTO) impulses. This paper develops a novel power transformer condition monitoring system (NCMS), which makes full use of CES to detect and diagnose the external impulses and internal defects and faults. Firstly, the NCMS carries out the wide-band measurement of CES. Secondly, the NCMS obtains data from supervisory control and data acquisition system (SCADAS), dissolved gases analysis (DGA) system, and other monitoring systems, and correlates these data using grey relational analysis (GRA). Finally, the NCMS detects the impulses and diagnoses defects and faults based on the correlation relationships, then presents the monitoring results to the users. This novel system has been applied to the field and successfully diagnosed many defects and faults. It has high accuracy (< 3%) at the power and harmonic frequencies and possesses the capability to capture VFTO-pulses. INDEX TERMS Correlation analysis, core earth signal (CES), condition monitoring, industry applications, power transformer, wide-band measurement.

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Creeping discharges propagating on natural ester oils/pressboard interface under AC and lightning impulse voltages

Cited by 21 publications

References 19 publications

Combined effect of lightning impulse voltage and temperature stress on the propagation of creeping discharge of oil-impregnated paper

Combined effect of lightning impulse voltage and temperature stress on the propagation of creeping discharge of oil-impregnated paper

Pre-Breakdown and Breakdown Behavior of Synthetic and Natural Ester Liquids under AC Stress

A Novel Power Transformer Condition Monitoring System Based on Wide-Band Measurement of Core Earth Signals and Correlation Analysis With Multi-Source Data

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