Fire safety and electrical properties of mixtures of synthetic ester/mineral oil and synthetic ester/natural ester

2018 ◽  
Vol 25 (5) ◽  
pp. 1846-1852 ◽  
Author(s):  
Grzegorz Dombek ◽  
Jaroslaw Gielniak
Keyword(s):  
Electrical Properties ◽  
Fire Safety ◽  
Mineral Oil ◽  
Synthetic Ester ◽  
Natural Ester

scholarly journals Dielectric properties of natural ester, synthetic ester midel 7131 and mineral oil diala D

2014 ◽  
Vol 21 (2) ◽  
pp. 644-652 ◽  
Author(s):  
Yi Jing ◽  
Igor Timoshkin ◽  
Mark Wilson ◽  
Martin Given ◽  
Scott Macgregor ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Mineral Oil ◽  
Synthetic Ester ◽  
Natural Ester

scholarly journals Effect of Moisture on the Thermal Conductivity of Cellulose and Aramid Paper Impregnated with Various Dielectric Liquids

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4433 ◽  
Author(s):  
Grzegorz Dombek ◽  
Zbigniew Nadolny ◽  
Piotr Przybylek ◽  
Radoslaw Lopatkiewicz ◽  
Agnieszka Marcinkowska ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Linear Equation ◽  
Heat Transport ◽  
Mineral Oil ◽  
Experimental Database ◽  
Synthetic Ester ◽  
Dielectric Liquids ◽  
Paper Insulation ◽  
The Impact ◽  
Natural Ester

This paper presents the effect of the impact of moisture in paper insulation used as insulation of transformer windings on its thermal conductivity. Various types of paper (cellulose and aramid) and impregnated (mineral oil, synthetic ester, and natural ester) were tested. The impact of paper and impregnated types on the changes in thermal conductivity of paper insulation caused by an increase in moisture were analyzed. A linear equation, describing the changes in thermal conductivity due to moisture, for various types of paper and impregnated, was developed. The results of measuring the thermal conductivity of paper insulation depending on the temperature are presented. The aim of the study is to develop an experimental database to better understand the heat transport inside transformers to assess aging and optimize their performance.

Fillers in Electrical Papers for Power Transformers

2014 ◽  
Vol 875-877 ◽  
pp. 335-340 ◽  
Author(s):  
Primo Alberto Calva ◽  
Aarón Israel Díaz ◽  
Hugo Martínez Gutierrez
Keyword(s):  
Electrical Properties ◽  
Theoretical Analysis ◽  
Structural Parameters ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Dielectric Behavior ◽  
Power Transformers ◽  
Mechanical Resistance ◽  
Kraft Paper ◽  
Natural Ester

The electric papers have a wide variety of uses like in transformers, cables and power capacitors. Each application involves different requirements related to its mechanical and electric properties. The kraft is the dielectric paper most used due its high mechanical resistance and a dielectric strength of around 5 kV/mm that is increased up to 30 kV/mm when is impregnated with mineral oil and typically has a density of 0.7, nevertheless continuous improvements in the design, for example, of power transformers raise the need to improve its electrical properties particularly those related to its relative permittivity. In this article, structural parameters such as distribution and pore size of kraft paper and theoretical analysis for possible addition of nanofillers to improve their dielectric behavior are reported. A possible and better criterion for designing transformers can be the employment of kraft paper nano-inserted with 5 % of TiO2 or BaTiO3 stew in mineral oil and immersed in natural ester liquid.

scholarly journals Application of Molecular Sieves for Drying Transformers Insulated with Mineral Oil, Natural Ester, or Synthetic Ester

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1719
Author(s):  
Mateusz Cybulski ◽  
Piotr Przybylek
Keyword(s):  
Molecular Sieves ◽  
Water Sorption ◽  
Sorption Isotherms ◽  
Mineral Oil ◽  
Drying Process ◽  
Insulation System ◽  
Synthetic Ester ◽  
Transformer Insulation ◽  
Natural Ester ◽  
Water Sorption Isotherms

A high level of moisture in the insulation system of power transformers is often the cause of their failure. This can be prevented by drying a transformer in its place of installation. In the article the application of molecular sieves (MS) in the drying process of the transformer insulation system was analyzed. The water sorption isotherms of 3A MS in mineral oil, natural ester, and synthetic ester at 35 °C were determined, which was not described in the literature before. An evaluation of the influence of temperature on the drying dynamics of electro-insulating liquids using MS was also carried out. The drying dynamics were tested at three temperatures, i.e., 35 °C, 50 °C, and 65 °C, which allowed to analyze the effect of temperature on a short-term or continuous drying process. The tests showed that 3A MS’s ability to adsorb water varied depending on the type of electro-insulating liquid. The determined water sorption isotherms, described by means of Langmuir adsorption model, make it possible to calculate the amount of MS needed for drying transformers with different liquid insulation. The research and analyses show the MS’s great potential for the drying of transformer insulation systems.

scholarly journals Influence of Molecule Structure on Lightning Impulse Breakdown of Ester Liquids

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1061
Author(s):  
Huaqiang Li ◽  
Linfeng Xia ◽  
Shengwei Cai ◽  
Zhiqiang Huang ◽  
Jiaqi Li ◽  
...  
Keyword(s):  
Electric Fields ◽  
Breakdown Voltage ◽  
Experimental Research ◽  
Environmentally Friendly ◽  
Mineral Oil ◽  
Positive Polarity ◽  
Mineral Oils ◽  
Synthetic Ester ◽  
Lightning Impulse ◽  
Natural Ester

Ester liquids are environmentally friendly insulating oils, and they can be used as an alternative to mineral oil in transformers, even though in most countries spills of ester oils must be treated like spills of mineral oil. Furthermore, the breakdown characteristics of ester liquids are worse than those of mineral oils in heterogeneous electric fields. In this paper, we present a comprehensive experimental research on both positive and negative lightning impulse breakdown properties in point-plane geometries with gaps varying from 1 mm to 50 mm. The breakdown voltages and streamer velocities of five kinds of ester liquids, including natural ester, synthetic ester, and three kinds of single component esters have been measured. The results show that the double bonds have no effect on the breakdown voltage of ester liquids. The average streamer velocities of mono-esters are faster than that of other esters under positive polarity, and the breakdown voltages of all esters are close.

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