Propagation of electrical discharges in small electrode gap of natural and synthetic ester under negative lightning impulse

2014 ◽  
Author(s):  
P. Rozga
Keyword(s):  
Electrical Discharges ◽  
Electrode Gap ◽  
Synthetic Ester ◽  
Lightning Impulse ◽  
Small Electrode ◽  
Natural And Synthetic

scholarly journals Streamer propagation in a non-uniform electric field under lightning impulse in short gaps insulated with natural ester and mineral oil

2016 ◽  
Vol 64 (1) ◽  
pp. 171-179 ◽  
Author(s):  
P. Rozga
Keyword(s):  
Light Emission ◽  
Experimental Studies ◽  
Mineral Oil ◽  
Uniform Electric Field ◽  
Light Pulses ◽  
Streamer Propagation ◽  
Lightning Impulse ◽  
Small Electrode ◽  
Acceleration Voltage ◽  
Natural Ester

Abstract This article describes the comparative experimental studies on streamer propagation in natural ester and mineral oil under a high voltage lightning impulse. These studies were concentrated around the small electrode gaps and the point-plane electrode arrangement. The spatial shapes of the developing streamers, light emission and propagation velocity were analyzed and compared between the two different dielectric liquids. In both of them two streamer propagation modes were registered during the studies performed. Propagation of slow 2nd mode streamers took place below the so-called acceleration voltage while fast 3rd mode streamers developed at acceleration voltage and above. Comparing the streamer shapes corresponding to a given voltage polarity, no visible differences were observed between the liquids tested. Concerning the light emission, higher frequencies of light pulses were registered however in the case of natural ester. The significant differences between both liquids were noticed in the value of the acceleration voltage estimated. In the case of positive polarity streamers started to develop in natural ester as a 3rd mode at lower value of testing voltage than in the case of mineral oil. For negative polarity, within the applied testing voltages, 3rd mode streamers appeared only in natural ester. On this basis, the fundamental conclusion is that natural ester may have a lower ability of preventing the development of fast and energetic 3rd mode streamers, even at small electrode gaps.

scholarly journals Breakdown in short rod-plane air gaps under positive lightning impulse stress

2017 ◽  
Author(s):  
Hans Kristian Hygen Meyer ◽  
Frank Mauseth ◽  
Martine Husøy ◽  
Atle Pedersen
Keyword(s):  
Prediction Models ◽  
Dark Period ◽  
Complex Geometries ◽  
Streamer Discharge ◽  
Electrical Discharges ◽  
Air Gaps ◽  
Breakdown Mechanism ◽  
Light Filters ◽  
Lightning Impulse ◽  
A Current

<p>Prediction of withstand voltages in air-insulated systems are made on the basis of empirical models that are not sufficiently accurate for complex geometries. Better understanding of the spatiotemporal development of electrical discharges is necessary to improve the present models. Discharges in lightning impulse stressed 20–100mm rod-plane gaps are examined using a highspeed camera, photo-multiplier tubes (PMTs) and a highbandwidth current measurement system. The images and measurements of gaps larger than 20mm show a fast initial streamer discharge with a current rise time of some tens of ns, followed by a dark period of a few μs and a propagation of a slower leader-type channel leading to breakdown. The breakdown mechanisms in the shortest gaps are faster and geometry dependent, probably occuring by heating of initial streamer channels. Different light filters used with the PMTs indicate that all parts of the leader-type discharge development emit light over a spectrum from UV to IR. The initial discharges emit low amounts of warm light and IR compared to the leader-type channel. Finally, it is suggested that empirical breakdown voltage prediction models should be interpreted in light of the leader-type breakdown mechanism.</p>

Breakdown Characteristics of Natural and Synthetic Ester Liquids When Containing Varying Levels of Moisture

2019 ◽  
Author(s):  
C. Williamson ◽  
I. Timoshkin ◽  
S. MacGregor ◽  
M. P. Wilson ◽  
M. J. Given ◽  
...  
Keyword(s):  
Synthetic Ester ◽  
Natural And Synthetic

scholarly journals A Review on Synthetic Ester Liquids for Transformer Applications

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6429
Author(s):  
Pawel Rozga ◽  
Abderrahmane Beroual ◽  
Piotr Przybylek ◽  
Maciej Jaroszewski ◽  
Konrad Strzelecki
Keyword(s):  
Review Paper ◽  
Research Work ◽  
Gas Analysis ◽  
Point Of View ◽  
Research Progress ◽  
Dissolved Gas ◽  
Synthetic Ester ◽  
Static Electrification ◽  
Fundamental Point ◽  
Lightning Impulse

Synthetic esters have become more and more popular in last few decades, explaining the increasing number of units filled with this liquid year by year. They have been investigated under different aspects, both from the fundamental point of view and breakdown mechanisms, well as from the application point of view. However, their use in high voltage equipment is always a challenge and deeper knowledge of the various aspects that can be encountered in their exploitation is needed. The intent of this review paper is to present the recent research progress on synthetic ester liquid in relation to the selected issues, most important for ester development in the authors’ opinion. The described issues are the breakdown performance of synthetic esters, lightning impulse strength and pre-breakdown phenomena of synthetic esters, synthetic esters-based nanofluids, combined paper-synthetic ester based insulating systems, application of synthetic ester for retro-filling and drying of mineral oil-immersed transformers, DGA(dissolved gas analysis)-based diagnosis of synthetic esters filled transformers as well as static electrification of synthetic esters. The different sections are based both on the data available in the literature, but above all on the authors’ own experience from their research work on synthetic ester liquids for electrical application purposes.

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