Investigating the Effects of Creepage Discharges on the Breakdown Voltage of Natural Ester Oil Impregnated Pressboard in Power Transformers

2020 ◽  
Author(s):  
Bakhekile Ndlovu ◽  
Cuthbert Nyamupngedengu
Keyword(s):  
Breakdown Voltage ◽  
Power Transformers ◽  
Natural Ester

scholarly journals Effect of repeated electrical breakdowns on mineral and natural ester insulating oils

2021 ◽  
Vol 10 (6) ◽  
pp. 2989-2996
Author(s):  
Sharin Ab Ghani ◽  
Mohd Shahril Ahmad Khiar ◽  
Imran Sutan Chairul ◽  
Muhammad Imran Zamir
Keyword(s):  
Breakdown Voltage ◽  
Electrical Discharge ◽  
Electrical Breakdown ◽  
Standard Test ◽  
Test Method ◽  
Power Transformers ◽  
Insulating Oil ◽  
Different Types ◽  
Increasing Demand ◽  
Natural Ester

Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests are conducted to analyze the ability of oil to resist decomposition due to such high electrical stresses. With the increasing demand for alternative insulating oils for oil-immersed transformers, it is worthy to compare the performance of different types of insulating oils (conventional mineral-based insulating oil and natural ester-based insulating oil) under repeated electrical breakdown. In this paper, the AC breakdown voltage of different mineral-based and natural ester-based insulating oils is reported. Durability tests were conducted based on the AC breakdown voltage behavior of insulating oils after 50 electrical breakdown shots. The AC breakdown voltage of each insulating oil sample was assessed according to the ASTM D1816 standard test method. Based on the results, it can be concluded that the dissimilarity in chemical composition of the insulating oils has a significant effect on the AC breakdown voltage behavior of these oils under repeated electrical breakdowns.

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>

scholarly journals Effect of TiO2 and ZnO Nanoparticles on the Performance of Dielectric Nanofluids Based on Vegetable Esters During Their Aging

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 692
Author(s):  
Inmaculada Fernández ◽  
Rafael Valiente ◽  
Félix Ortiz ◽  
Carlos J. Renedo ◽  
Alfredo Ortiz
Keyword(s):  
Breakdown Voltage ◽  
Vegetable Oil ◽  
Thermal Aging ◽  
Heat Dissipation ◽  
Dissipation Factor ◽  
Dielectric Behavior ◽  
Degree Of Polymerization ◽  
Point Of View ◽  
Transformer Oils ◽  
Natural Ester

Over the last few decades the insulating performance of transformer oils has been broadly studied under the point of view of nanotechnology, which tries to improve the insulating and heat dissipation performance of transformer oils by suspending nanoparticles. Many authors have analyzed the thermal and dielectric behavior of vegetable oil based-nanofluids, however, very few works have studied the evolution of these liquids during thermal aging and their stability. In this paper has been evaluated the performance of aged vegetable oil based-nanofluids, which have been subjected to accelerated thermal aging at 150 °C. Nanoparticles of TiO2 and ZnO have been dispersed in a commercial natural ester. Breakdown voltage, resistivity, dissipation factor and acidity of nanofluid samples have been measured according to standard methods, as well as stability. Moreover, it has been analyzed the degradation of Kraft paper through the degree of polymerization (DP). The results have showed that although nanoparticles improve breakdown voltage, they increase the ageing of insulation liquids and dielectric paper.

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