scholarly journals Influence of ageing on oil degradation and gassing tendency under high-energy electrical discharge faults for mineral oil and synthetic ester

High Voltage ◽  
2020 ◽  
Vol 5 (6) ◽  
pp. 731-738 ◽  
Author(s):  
L. Loiselle ◽  
U. Mohan Rao ◽  
I. Fofana
Keyword(s):  
Electrical Discharge ◽  
High Energy ◽  
Mineral Oil ◽  
Oil Degradation ◽  
Synthetic Ester

Electrophysical properties of mixtures of mineral oil and synthetic ester dielectric liquid

2021 ◽  
Vol 14 (2) ◽  
pp. 132-141
Author(s):  
M. N. Lyutikova ◽  
S. M. Korobeynikov ◽  
A. A. Konovalov
Keyword(s):  
Dielectric Loss ◽  
Breakdown Voltage ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Kinematic Viscosity ◽  
Mineral Oil ◽  
Flash Point ◽  
Power Transformers ◽  
Synthetic Ester ◽  
Insulating Properties

Power transformers are key equipment in power generation, transmission, and distribution systems. The reliability of power transformers is based on the performance of the insulation system, which includes solid cellulose insulation and a liquid dielectric. Modern power engineering requires liquid insulation to have excellent insulating properties, high fire resistance, and biodegradability. Mineral oil that has been in use for over 100 years does not meet certain requirements. Therefore, various methods of enhancing the insulating properties of the oil are currently being considered, including mixing it with other liquid dielectrics, which have excellent properties. Synthetic and natural esters are considered as alternative fluids.This article discusses the possibility of enhancing the insulating characteristics of mineral oil with a high content of aromatic hydrocarbons (for example, T-750 oil) by mixing it with synthetic ester Midel 7131. Assessment is given of insulating parameters of the resulting mixtures with an ester fraction in mineral oil from 0% to fifty%. The main characteristics of the mixtures are described, such as density, kinematic viscosity, flash point, dielectric loss tangent, relative dielectric permittivity, breakdown voltage, and moisture content. It is shown that with an increase in the proportion of ester, some parameters of the obtained insulating liquid improve (flash point, dielectric constant, breakdown voltage), while values of other parameters (density, kinematic viscosity, dielectric loss tangent) with an ester content of more than 10% in the mixture do not meet the requirements for mineral oils.

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>

Numerical and Experimental Study on Micro-Electrical Discharge Micromachining Characteristics on Molybdenum

2005 ◽  
Author(s):  
Phil Allen ◽  
Xiaolin Chen ◽  
Dave Kim
Keyword(s):  
Numerical Model ◽  
Electrical Discharge ◽  
High Energy ◽  
Spark Discharge ◽  
Discharge Process ◽  
Micro Edm ◽  
Micron Size ◽  
Mechanical And Physical Properties ◽  
Machining Characteristics ◽  
Edm Process

Electrical discharge micromachining (micro-EDM) is an ideal process for obtaining burr-free machined micron-size apertures. Molybdenum is one of the most attractive high energy and power aperture materials due to its mechanical and physical properties, mainly its high melting temperature and relatively high thermal conductivity. In this paper, fundamental machining characteristics for micro-EDM of molybdenum were investigated both numerically and experimentally. A thermo-numerical model was created to simulate a single spark discharge process. Experimental crater size is investigated using scanning electron microscopy and optical evaluation methods. The effects of important EDM parameters such as the pulse duration on crater shape, temperature distribution, tool wear percentage, and eroded volume were studied. Correlations between numerical and experimental data are also discussed. The model effectively estimates the size of single spark craters in molybdenum. The results show that the developed thermo-numerical model can be an effective tool in predicting the size of a crater formed by a single spark discharge in the micro-EDM process.

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.

Lubrication in Push-Through Bending on Bending of Aluminum Extrusion Section

2013 ◽  
Vol 459 ◽  
pp. 432-439
Author(s):  
Hidemitsu Hamano ◽  
Hisaki Watari
Keyword(s):  
Contact Area ◽  
Good Alternative ◽  
Mineral Oil ◽  
Aluminum Extrusion ◽  
Alcohol Content ◽  
Synthetic Ester ◽  
Bending Process ◽  
Lubrication Oil ◽  
Bending Mechanism

The push-through bending process can be regarded as a bending mechanism with two fixed diepoints and two movable diepoints, resulting in a total of four points. It can also be regarded as acontinuous four-points bending. As compared to other bending processes, there is severe friction at the contact area betweenthematerial and die in push-through bending. In this paper, we clarify different aspects of lubrication and research excellent lubrication oil in push-through bending. Based on theresultsobtained, it was found that adhesion occursdepending on the lubricant used and the occurring force. It was also confirmed, that olefin is effective as a remedy for oiliness, in case of using a mineral oil-based lubricant. In addition, it was confirmed that excellent lubrication oil could be obtained by increasing the alcohol content and adjusting the content of synthetic ester. This is a good alternative to the more expensive olefin.

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