Thermal degrade analysis of solid insulating materials immersed in natural ester oil and mineral oil by DGA

2021 ◽  
Author(s):  
Shaik Rafi Kiran ◽  
T. Mariprasath ◽  
CH Hussaian Basha ◽  
M. Murali ◽  
M. Bhaskara Reddy
Keyword(s):  
Mineral Oil ◽  
Insulating Materials ◽  
Natural Ester

scholarly journals Investigation of Survival/Hazard Rate of Natural Ester Treated with Al2O3 Nanoparticle for Power Transformer Liquid Dielectric

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1510
Author(s):  
Raymon Antony Raj ◽  
Ravi Samikannu ◽  
Abid Yahya ◽  
Modisa Mosalaosi
Keyword(s):  
Survival Rate ◽  
Hazard Rate ◽  
Power Transformer ◽  
Mineral Oil ◽  
Interpolation Polynomial ◽  
Distribution Functions ◽  
Flash Fire ◽  
Predicted Values ◽  
Natural Ester ◽  
Electrical Apparatus

Increasing usage of petroleum-based insulating oils in electrical apparatus has led to increase in pollution and, at the same time, the oils adversely affect the life of electrical apparatus. This increases the demand of Mineral Oil (MO), which is on the verge of extinction and leads to conducting tests on natural esters. This work discusses dielectric endurance of Marula Oil (MRO), a natural ester modified using Conductive Nano Particle (CNP) to replace petroleum-based dielectric oils for power transformer applications. The Al2O3 is a CNP that has a melting point of 2072 °C and a low charge relaxation time that allows time to quench free electrons during electrical discharge. Al2O3 is blended with the MRO and Mineral Oil (MO) in different concentrations. The measured dielectric properties are transformed into mathematical equations using the Lagrange interpolation polynomial functions and compared with the predicted values either using Gaussian or Fourier distribution functions. Addition of Al2O3 indicates that 0.75 g/L in MRO has an 80% survival rate and 20% hazard rate compared to MO which has 50% survival rate and 50% hazard rate. Considering the measured or interpolated values and the predicted values, they are used to identify the MRO and MO’s optimum concentration produces better results. The test result confirms the enhancement of the breakdown voltage up to 64%, kinematic viscosity is lowered by up to 40% at 110 °C, and flash/fire points of MRO after Al2O3 treatment enhanced to 14% and 23%. Hence the endurance of Al2O3 in MRO proves to be effective against electrical, physical and thermal stress.

scholarly journals Alternative liquid dielectrics in power transformer insulation: a review

2021 ◽  
Vol 23 (3) ◽  
pp. 1761
Author(s):  
Bokang Agripa Tlhabologo ◽  
Ravi Samikannu ◽  
Modisa Mosalaosi
Keyword(s):  
Power Transformer ◽  
Chemical Properties ◽  
Fire Risk ◽  
Mineral Oil ◽  
Acid Number ◽  
Gas Analysis ◽  
International Standards ◽  
Liquid Dielectrics ◽  
Transformer Insulation ◽  
Natural Ester

Transformer liquid dielectrics evolved where mineral oil has been the dominant choice until emergence of synthetic esters and natural esters. Natural ester-based oils have been under extensive investigations to enhance their properties for replacing petroleum-based mineral oil, which is non-biodegradable and has poor dielectric properties. This paper focuses on exposition of natural ester oil application in mixed transformer liquid dielectrics. Physical, chemical, electrical, and ageing characteristics of these dielectrics and the dissolved gas analysis (DGA) were reviewed. Physical properties include viscosity, pour point, flash and fire point which are vital indicators of heat insulation and fire risk. Chemical properties considered are water content, acid number, DGA, corrosive sulphur, and sludge content to limit and detect degradation and corrosion due to oil ageing. Electrical properties including breakdown voltage were considered for consistent insulation during overload and fault conditions. These properties of evolving alternative dielectrics were reviewed based on ASTM International standards and International Electro technical Commission standards for acceptable transformer liquid dielectrics. This review paper was compiled to avail modern methodologies for both the industry and scholars, also providing the significance of using mixed dielectrics for power transformers as they are concluded to show superiority over non-mixed dielectrics.

scholarly journals Effect of electrical discharge on the properties of natural esters insulating fluids

2021 ◽  
Vol 23 (3) ◽  
pp. 1281
Author(s):  
Imran Sutan Chairul ◽  
Sharin Ab Ghani ◽  
Nur Hakimah Ab Aziz ◽  
Mohd Shahril Ahmad Khiar ◽  
Muhammad Syahrani Johal ◽  
...  
Keyword(s):  
Water Content ◽  
Breakdown Voltage ◽  
Electrical Discharge ◽  
Mineral Oil ◽  
Electrical Discharges ◽  
Inhomogeneous Electric Field ◽  
Sustainable Resources ◽  
Low Viscosity ◽  
Environmental Friendly ◽  
Natural Ester

<p>Vegetable oils have been an alternative to mineral oil for oil-immersed transformers due to concern on less flammable, environmental-friendly, biodegradable, and sustainable resources of petroleum-based insulating oil. This paper presents the effect of electrical discharges (200 up to 1000 discharges) under 50 Hz inhomogeneous electric field on the properties (acidity, water content, and breakdown voltage) of two varieties of vegetable based insulating oils; i) natural ester (NE) and ii) low viscosity insulating fluids derived from a natural ester (NE<sub>LV</sub>). Results show the water content, acidity and breakdown voltage of NE fluctuate due to applied discharges, while NE<sub>LV</sub> display insignificant changes. Hence, results indicate that the low viscosity insulating fluids derived from natural ester tend to maintain their properties compared to natural ester.</p>

scholarly journals Difference Analysis of Gas Molecules Diffusion Behavior in Natural Ester and Mineral Oil Based on Molecular Dynamic Simulation

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4463 ◽  
Author(s):  
Wenyu Ye ◽  
Jian Hao ◽  
Yufeng Chen ◽  
Mengzhao Zhu ◽  
Zhen Pan ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Interaction Energy ◽  
Free Volume ◽  
Mean Square Displacement ◽  
Mineral Oil ◽  
Relative Molecular Mass ◽  
Diffusion Behavior ◽  
Influence Of Temperature On ◽  
Gas Molecules ◽  
Natural Ester

Natural ester, as a new environmentally green insulating oil, has been widely used in transformer. In an oil-immersed transformer, the normal aging, thermal failure, and discharge failure could easily lead to the decomposition of the oil-paper insulation system and produce different kinds of gases. Studying gas dissolution in natural ester and mineral oil could provide assistance in applying criteria to make a diagnosis of different kinds of faults in the transformer. In this paper, the molecular dynamics method was used to investigate the diffusion behavior of seven fault characteristic gases (including H2, CO, CH4, C2H2, CO2, C2H4, C2H6) in natural ester and mineral oil. The simulation parameters of free volume, interaction energy, mean square displacement, and diffusion coefficient were compared between the natural ester and mineral oil. Meanwhile, the influence of temperature on the diffusion of gas molecules in two kinds of oils was also analyzed. Results showed that the free volume, the interaction energy, and the relative molecular mass of gas molecules were the factors influenced by the diffusion of gas molecules in natural ester and mineral oil. The order of the diffusion coefficients of gas molecules in natural ester was as follows: H2 > CH4 > CO > C2H2 > C2H4 > CO2 > C2H6 and that in mineral oil was as follows: H2 > CH4 > CO> C2H2 > C2 H4 > C2H6 > CO2. By comparing the diffusion behavior of gas molecules in natural ester and mineral oil, it was found that the smaller free volume and higher interaction energy of gas molecules in natural ester were the major reasons for the gas molecules to be more difficult to diffuse in natural ester. The rising temperature could enhance the free volume and reduce the interaction energy between gas molecules and oil. The diffusion coefficient of gas molecules increased exponentially with the follow of temperature. However, the temperature didn’t affect the ordering of diffusion coefficient, free volume, and interaction energy of gas molecules in natural ester and mineral oil.

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