Application of statistical methods simplified to the testing of dielectric strength of insulating liquids

2000 ◽  
Author(s):  
C. De Souza Marchi
Keyword(s):  
Statistical Methods ◽  
Dielectric Strength ◽  
Insulating Liquids

Moisture effects on AC dielectric strength and partial discharge inception voltage in natural monoesters

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Emeric Tchamdjio Nkouetcha ◽  
Ghislain Mengata Mengounou ◽  
Adolphe Moukengue Imano
Keyword(s):  
Water Contamination ◽  
Partial Discharge ◽  
Palm Kernel ◽  
Dielectric Strength ◽  
Glycerol Solution ◽  
Humid Environment ◽  
Insulating Liquids ◽  
Moisture Effects ◽  
Dielectric Performance ◽  
Inception Voltage

Abstract It is essential to analyse the dielectric performance in a humid environment of insulating liquids of plant origin, considered as alternatives to mineral oil (MO) which is not environmentally friendly. This paper focuses on the effects of different moisture levels on the dielectric strength and partial discharge initiation voltage of two natural monoesters, based on castor oil (CO) and palm kernel oil (PKO), and MO. The different samples were moistened with a glycerol solution, then sealed and stored for 12 days to allow further diffusion of moisture into the samples. Dielectric strength was statistically evaluated from IEC 60156. Partial discharge inception voltage (PDIV) experiment was performed in conformity with a modified IEC 61294 purpose at ambient temperature. Based on the experimental observations, the moisture has different behavior on dielectric strength and PDIV of insulating oils. Monoesters have a better withstand to water contamination than MOs in power transformers.

Investigation on the Dielectric Properties of Palm Oil with Silicon Carbide Doping for Transformer Application

2021 ◽  
Vol 317 ◽  
pp. 377-382
Author(s):  
Muhamad Faiz Md Din ◽  
Nurul Sofea Mazlan ◽  
ABDUL RASHID BIN ABDUL RAHMAN ◽  
Mohd Taufiq Jusoh ◽  
Nur Sabrina Suhaimi ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Breakdown Voltage ◽  
Palm Oil ◽  
Dielectric Strength ◽  
Dissipation Factor ◽  
Electrode Gap ◽  
Insulating Liquids ◽  
Transformer Oils ◽  
Tan Δ ◽  
Dielectric Dissipation Factor

The dielectric strength of insulating liquids of transformer acts an important parameter in the operation of transformer. Thus, great interest and many studies have been extensively done to improve the dielectric strength. One of study is the introduction of nanoparticle in the transformer oils. Study of the nanoparticles for the last few years had been found that, it can be dispersed in the transformers oils to be nanofluids and directly enhance the transformer performance. In this study, an investigation has been carried out to focus on the effect of silicon carbide (SiC) nanoparticle to AC (alternating current) breakdown voltage of the Refined, Bleached, and Deodorized Palm Oil (RBDPO). AC breakdown test have been conduct according to the standard of the IEC 60156. Besides that, a number of parameters will be evaluated such as dielectric dissipation factor (tan δ), relative permittivity (ε), and resistivity (ρ). Based on the results of the experiment, the electrode gap at 2.5 mm having the highest AC breakdown voltage compared to the other electrode gap which are 1.0 mm, 1.5 mm and 2.0 mm. Furthermore, doping with different concentrations of the silicon carbide (SiC) in Refined, Bleached, and Deodorized Palm Oil (RBDPO) found decreasing of AC breakdown voltage from 52.09 kV (without SiC) to 45.3 kV for 0.001 g/L, 43.2 kV for 0.003 g/L and 40.1 kV for 0.005 g/L respectively.

scholarly journals Lightning Impulse Withstand of Natural Ester Liquid

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1964 ◽  
Author(s):  
Stephanie Haegele ◽  
Farzaneh Vahidi ◽  
Stefan Tenbohlen ◽  
Kevin Rapp ◽  
Alan Sbravati
Keyword(s):  
Breakdown Voltage ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Homogeneous Field ◽  
Inhomogeneous Field ◽  
Insulating Liquids ◽  
Lightning Impulse ◽  
Insulating Liquid ◽  
Natural Ester ◽  
Inhomogeneity Factor

Due to the low biodegradability of mineral oil, intense research is conducted to define alternative liquids with comparable dielectric properties. Natural ester liquids are an alternative in focus; they are used increasingly as insulating liquid in distribution and power transformers. The main advantages of natural ester liquids compared to mineral oil are their good biodegradability and mainly high flash and fire points providing better fire safety. The dielectric strength of natural ester liquids is comparable to conventional mineral oil for homogeneous field arrangements. However, many studies showed a reduced dielectric strength for highly inhomogeneous field arrangements. This study investigates at which degree of inhomogeneity differences in breakdown voltage between the two insulating liquids occur. Investigations use lightning impulses with different electrode arrangements representing different field inhomogeneity factors and different gap distances. To ensure comparisons with existing transformer geometries, investigations are application-oriented using a transformer conductor model, which is compared to other studies. Results show significant differences in breakdown voltage from an inhomogeneity factor of 0.1 (highly inhomogeneous field) depending on the gap distance. Larger electrode gaps provide a larger inhomogeneity at which differences in breakdown voltages occur.

scholarly journals Dealing with the Size Effect in Insulating Liquids. A Volume Effect, an Area Effect or even a Particle Effect?

2020 ◽  
Vol 10 (5) ◽  
pp. 6231-6236
Author(s):  
M. Danikas ◽  
R. Sarathi ◽  
G. E. Vardakis ◽  
S. Morsalin
Keyword(s):  
Size Effect ◽  
Dielectric Strength ◽  
Short Review ◽  
Volume Effect ◽  
Liquid Volume ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Insulating Liquids ◽  
Insulating Liquid ◽  
Gap Spacing

Insulating liquids play an important role as insulating media in various high voltage applications and infrastructure installations. The dielectric strength of an insulating liquid depends on the experimental conditions (in case of laboratory testing) and/or the service conditions (in case of apparatuses in service). One of the main factors affecting the dielectric strength of insulating liquids is the so-called size effect, i.e. the effect of the size of the electrodes, of the size of the liquid volume under stress and of the gap spacing between the electrodes. All the aforementioned parameters are investigated in the context of the present short review.

scholarly journals Bubbles in Insulating Liquids: A Short Review

2019 ◽  
Vol 9 (6) ◽  
pp. 4870-4875
Author(s):  
M. Danikas
Keyword(s):  
Electric Field ◽  
Dielectric Strength ◽  
Short Review ◽  
Dielectric Liquids ◽  
Insulating Liquids

This paper deals with the influence of bubbles in insulating liquids and their role in liquid breakdown. Bubbles play a deleterious role in the dielectric strength of insulating liquids. Depending on their shape and localized electric field, bubbles may significantly lower the dielectric strength of insulating liquids. The present paper offers a short review – albeit incomplete – on the role of bubbles and tries to elucidate their relation to the total breakdown of dielectric liquids. It also proposes some further fields of research.

Statistics and parallaxes

1978 ◽  
Vol 48 ◽  
pp. 7-29
Author(s):  
T. E. Lutz
Keyword(s):  
Experimental Design ◽  
Statistical Methods ◽  
Review Paper ◽  
Systematic Errors ◽  
Past Experience ◽  
Random Errors ◽  
Trigonometric Parallaxes ◽  
Systematic And Random Errors

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.

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