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

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 167
Author(s):  
Beki Sékongo ◽  
Stephan Brettschneider ◽  
U. Mohan Rao ◽  
Issouf Fofana ◽  
Marouane Jabbari ◽  
...  
Keyword(s):  
Electric Field ◽  
Thermal Aging ◽  
Power Transformer ◽  
Partial Discharge ◽  
Service Condition ◽  
Mineral Oil ◽  
Radius Of Curvature ◽  
Long Term Behavior ◽  
Inception Voltage

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.

scholarly journals Effect of Test Method and Needle Plane Configuration on Partial Discharge Inception Voltage Measurement of Mineral Oil based on Weibull Analysis

2013 ◽  
Vol 11 ◽  
pp. 411-418 ◽  
Author(s):  
T.F. Sipahutar ◽  
A.A. Kemma ◽  
N. Pattanadech ◽  
F. Pratomosiwi ◽  
Suwarno ◽  
...  
Keyword(s):  
Partial Discharge ◽  
Mineral Oil ◽  
Test Method ◽  
Weibull Analysis ◽  
Voltage Measurement ◽  
Inception Voltage

scholarly journals Development of Partial Discharge Signal in Ester Oil Impregnated Paper

2020 ◽  
Vol 9 (4) ◽  
pp. 2516-2522
Keyword(s):  
Experimental Investigation ◽  
Power Transformer ◽  
Partial Discharge ◽  
Statistical Parameter ◽  
Dielectric Materials ◽  
Mineral Oil ◽  
Air Gap ◽  
Electrode Configuration ◽  
Discharge Activity

Power transformer is the most exorbitant and controversially the most essential equipment. Insulation abortion in transformer can cause stretched term interruption to supply and loss of revenue and the important maintenance procedure. The power transformer consists of organic insulation like Mineral oil, pressboard and paper. In impecunious of bio- degradability and availability, ester oil is replaced by Mineral oil. The partial discharge is a tool for evaluate the insulation atrophy of dielectric materials. In this paper the results of a laboratory based experimental investigation of partial discharge activity in oil – impregnated paper. To guesstimate the statistical parameter for different electrode configuration like different configuration under open air gap condition.

scholarly journals Analysis of Partial Discharge Due to Movement of Spherical Particle in Power Transformer Using Computational Fluid Dynamics

2018 ◽  
Vol 7 (3.3) ◽  
pp. 73
Author(s):  
N Vasantha Gowri ◽  
M Ramalinga Raju ◽  
B P.Singh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Spherical Particle ◽  
Power Transformer ◽  
Partial Discharge ◽  
Movement Pattern ◽  
Mineral Oil ◽  
Power Sector ◽  
Copper Particles ◽  
Conducting Particle

Power transformer is costly and very important equipment in power sector. Failure of power transformer causes colossal damage to the power system. One of the important reasons for transformer failure is event of Partial Discharge (PD) in the transformer. Numbers of non-conducting and conducting particle are available in the transformer. Conducting particles available in the transformer or mineral oil entering into winding space, strike the energized winding of the transformer cause PD to occur. Movement pattern of particle administrates the probability of particle striking the winding. Analysis of movement of particles proximate to HV winding helps in understanding the occurrence of PD. This paper deals with tracking of aluminum and copper particles of various sizes available inside the transformer. 

scholarly journals Development Processes of Surface Trucking and Partial Discharge of Pressboards Immersed in Mineral Oil: Effect of Tip Curvatures

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 554 ◽  
Author(s):  
Bo Gao ◽  
Rui Yu ◽  
Guangcai Hu ◽  
Cheng Liu ◽  
Xin Zhuang ◽  
...  
Keyword(s):  
High Speed ◽  
Weak Link ◽  
Partial Discharge ◽  
Mineral Oil ◽  
Tangential Component ◽  
Surface Tracking ◽  
Damage Degree ◽  
Development Processes ◽  
Paper Insulation

The pressboard surface is the electric weak link of the oil-paper insulation in transformers, and long-term partial discharge (PD) erosion is the dominant cause of degradation in pressboard. To explore the development processes of surface tracking under the effect of tip curvature, the typical needle-plate model was selected to initiate an electric field with a high tangential component on pressboard surface under needle tip curvature of 4~42 μm. With the help of a high-speed camera and a PD detecting system, the development processes of surface tracking and PD were recorded under a sustained AC voltage. A profound difference between surface tracking under different curvatures was discussed. Pressboard surfaces after tests were observed under a scanning electron microscope (SEM), and the damage degree of cellulose fibers was dependent on the tip curvature.

scholarly journals Using the Method of Harmonic Distortion Analysis in Partial Discharge Assessment in Mineral Oil in a Non-Uniform Electric Field

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4830
Author(s):  
Alper Aydogan ◽  
Fatih Atalar ◽  
Aysel Ersoy Yilmaz ◽  
Pawel Rozga
Keyword(s):  
Electric Field ◽  
Leakage Current ◽  
High Voltage ◽  
Partial Discharge ◽  
Harmonic Distortion ◽  
Mineral Oil ◽  
Significant Rise ◽  
Partial Discharges ◽  
Uniform Electric Field ◽  
Different Diameters

In high-voltage equipment, it is vital to detect any failure in advance. To do this, a determination of the partial discharges occurring at different voltage types as well as at different electrode configurations is essential for observing the oil condition. In this study, an experimental setup consisting of a needle–semi-sphere electrode configuration immersed in mineral oil is prepared for laboratory experiment. In such a way, a non-uniform electric field is created and the leakage currents are monitored from the grounded electrode. A total of six different electrode configurations are analyzed during the tests by the use of hemispheres of different diameters as grounded electrodes and copper and steel pointed (medical) needle high-voltage electrodes. In the experiments, the partial discharges occurring at four different voltage levels between 5.4 and 10.8 kV are measured and recorded. The effect of the different electrode configurations and voltage levels on the harmonic distortion are noted and discussed. It is experimentally confirmed that it is possible to measure the leakage current caused by the partial discharges of the corona type in oil at the different metal points, creating high-voltage electrodes and different electric field distributions based on the proposed non-invasive measurement technique. The studies showed that there is a significant rise of even harmonic components in the leakage current during the increase in the partial discharge intensity with the 5th harmonic as dominant.

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