scholarly journals The Effect of Electronic Scavenger Additives on the AC Dielectric Strength of Transformer Mineral Oil

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2607 ◽  
Author(s):  
Usama Khaled ◽  
Abderrahmane Beroual
Keyword(s):  
Carbon Tetrachloride ◽  
Weibull Distribution ◽  
Normal Distribution ◽  
Breakdown Voltage ◽  
Methyl Iodide ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Optimum Concentration ◽  
Maximum Value ◽  
Two Phases

This paper is devoted to the influence of two types of electronic scavenger additives/compounds, namely, carbon tetrachloride (CCl4) and methyl iodide, which is also called iodomethane (CH3I), on the dielectric strength of transformer mineral oil. The tests are achieved in a sphere-sphere electrodes arrangement under AC voltage according to the IEC 60156 standard. The investigated additive concentrations range from 0 to 600 ppm. The verification of the conformity of the experimental results with normal and Weibull probabilistic distributions as well as the estimation of the breakdown voltage with risk probabilities of 1%, 10%, and 50% are also performed. It is shown that there is an optimum concentration of each type of electronic scavenger compound at which the dielectric strength of the mineral oil is significantly improved (i.e., it reaches a maximum value). This improvement is of 98% with 500 ppm of CH3I and 93% with 200 ppm of CCl4. It is also shown that the breakdown voltage values of all of the investigated samples with and without additives conform to a Weibull distribution but not to a normal distribution. The obtained results are discussed with regard to the possible mechanisms that may be responsible, particularly the two phases of inception and propagation of the streamers.

scholarly journals AC Dielectric Strength of Mineral Oil-Based Fe3O4 and Al2O3 Nanofluids

2018 ◽  
Author(s):  
Usama Khaled ◽  
Abderrahmane Beroual
Keyword(s):  
Breakdown Voltage ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Sem Images ◽  
X Ray ◽  
Nanostructured Particles ◽  
Eds Analysis ◽  
Experimental Findings ◽  
Scanning Electron

This paper deals with experimental study of the influence of conductive (Fe3O4) and insulating (Al2O3) nanostructured particles at various concentrations on the dielectric strength of transformer mineral oil. The method of preparation and characterization of these nanofluids (NFs) through the measurements of zeta potential, the real and imaginary parts of dielectric constant as well as the concentration and size of nanoparticles using Scanning Electron Microscope (SEM) images of nanoparticles powders and Dispersive x-ray Spectroscopy (EDS) analysis are presented. Experimental findings reveal that these two types of nanoparticles materials significantly improve AC breakdown voltage and the magnitude of this improvement depends on the concentration, size and nature (material) of nanoparticles. For a given type of nanoparticles, the effect is more marked with the smallest nanoparticles. The conductive nanoparticles offer higher enhancement of dielectric strength compared with insulating nanoparticles based nanofluids. With Fe3O4, the breakdown voltage (BDV) can exceed twice that of mineral oil and it increases by more than 76% with Al2O3. The physicochemical mechanisms implicated in this improvement are discussed.

scholarly journals Statistical Analysis of AC Dielectric Strength for Palm Oil under the Influence of Moisture

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Muhammad Safwan Shukri ◽  
Norhafiz Azis ◽  
Jasronita Jasni ◽  
Robiah Yunus ◽  
Zaini Yaakub
Keyword(s):  
Statistical Analysis ◽  
Moisture Content ◽  
Weibull Distribution ◽  
Breakdown Voltage ◽  
Palm Oil ◽  
Statistical Study ◽  
Dielectric Strength ◽  
Statistical Analyses ◽  
Time Intervals ◽  
Moisture Contents

This paper presents a statistical study on the AC Breakdown Voltage (BDV) of Refined, Bleached and Deodorized Palm Oil (RBDPO) olein under the influence of moisture. Different moisture contents of the RBPDPO were prepared by drying the RBDPO in the oven at different time intervals. The AC BDV test of RBDPO was performed whereby the distance between 2 electrodes was set to 1 mm. The statistical analyses of AC BDV data for RBDPO were carried out based on normal, lognormal and Weibull distributions. It was shown that as the moisture content increased, the AC BDV of RDBPO decreased exponentially. Statistical analyses revealed that the AC BDV data with different moisture contents had platykurtic distributions. Moisture could influence the skewness of the distribution whereby the tail shifted from right to left as the content increased. At different moisture contents of RBDPO, most of the AC BDV data of RBDPO could be represented by Weibull distribution.

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.

Polyimide Passivation Effect on High Voltage 4H-SiC PiN Diode Breakdown Voltage

2009 ◽  
Vol 615-617 ◽  
pp. 695-698 ◽  
Author(s):  
Sombel Diaham ◽  
Marie Laure Locatelli ◽  
Thierry Lebey ◽  
Christophe Raynaud ◽  
Mihai Lazar ◽  
...  
Keyword(s):  
Thick Film ◽  
Breakdown Voltage ◽  
High Voltage ◽  
Electrical Characterization ◽  
Dielectric Strength ◽  
Pin Diode ◽  
Film Properties ◽  
Pin Diodes ◽  
Maximum Value

A polyimide (PI) has been used for the passivation of maximum 7.8 kV 4H-SiC P+N–N+ (PiN) diodes with a 60 µm-thick base epilayer and a junction termination extension (JTE) periphery protection. The dielectric strength of PI films is studied versus area and temperature. The reverse electrical characterization of the PI–passivated PiN diodes is presented for different natures of the environmental atmosphere. The results are compared to those obtained from same devices passivated with a deposited SiO2 thick film. The highest experimental breakdown voltages are obtained for PI–passivated PiN diodes immersed in PFPE oil, with a 5-6 kV typical value, and a 7.3 kV maximum value. Experimental observations are discussed in correlation with the insulating film properties.

scholarly journals AC Dielectric Strength of Mineral Oil-Based Fe3O4 and Al2O3 Nanofluids

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3505 ◽  
Author(s):  
Usama Khaled ◽  
Abderrahmane Beroual
Keyword(s):  
Breakdown Voltage ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Al2o3 Nanoparticles ◽  
Nanoparticle Concentration ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Microscope Images ◽  
Experimental Findings

This paper deals with an experimental study of the influence of conductive (Fe3O4) and insulating (Al2O3) nanoparticles at various concentrations on the dielectric strength of transformer mineral oil. The method of preparation and characterization of these nanofluids (NFs) through the measurements of zeta potential, the real and imaginary parts of dielectric permittivity as well as the concentration and size of nanoparticles using scanning electron microscope images of nanoparticles powders and energy dispersive x-ray spectroscopy analysis are presented. Experimental findings reveal that these two types of nanoparticles materials significantly improve AC breakdown voltage and the magnitude of this enhancement depends on the nanoparticle concentration, and the size and nature (material) of nanoparticles. For a given type of nanoparticle, the effect is more marked with the smallest nanoparticles. The conductive nanoparticles offer higher enhancement of dielectric strength compared with insulating nanoparticle based nanofluids. With Fe3O4, the breakdown voltage (BDV) can exceed twice that of mineral oil and it increases by more than 76% with Al2O3. The physicochemical mechanisms implicated in this improvement are discussed.

scholarly journals Virgin coconut oil dielectrical properties as electrical insulation material

2019 ◽  
Vol 8 (3) ◽  
pp. 1154-1161
Author(s):  
Siti Syafiqah Mat Sauki ◽  
Nor Asiah Muhamad ◽  
Zawani Amirah Rasid
Keyword(s):  
Breakdown Voltage ◽  
Kinematic Viscosity ◽  
Coconut Oil ◽  
Renewable Resource ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Heating Process ◽  
Insulation Material ◽  
Virgin Coconut Oil ◽  
Tropical Country

Mineral oil played an important role as insulating liquid such as to reduce failure, ageing effect, increase the life span and heat transfer agent. Mineral oil had a good dielectric strength and cooling performance but it had serious negative environmental impact like non-biodegradable, non-renewable resource and difficult to dispose when it deteriorates completely. Hence, virgin coconut oil (VCO) was chosen as alternative to replace mineral oil since it biodegrades completely without toxic and easy to get in the tropical country. Three dielectric tests were conducted to investigate the dielectric properties of VCO. Those were breakdown voltage, water content and kinematic viscosity. A study about the effect of the moisture level of VCO on the breakdown voltage and kinematic viscosity was also presented. VCO and mineral oil also undergone heating process to reduce moisture in sample. The study showed that VCO has good potential breakdown voltage with the ability to absorb a lot of moisture keeping the KRAFT paper dry. However, VCO had very high kinematic viscosity compared to mineral oil. Further, the rate of breakdown voltage decreases with increasing of moisture of VCO was lower than mineral oil.

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.

Effect of Water on Electrical Properties of Refined, Bleached, and Deodorized Palm Oil (RBDPO) as Electrical Insulating Material

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Nazera Ismail ◽  
Yanuar Z. Arief ◽  
Zuraimy Adzis ◽  
Shakira A. Azli ◽  
Abdul Azim A. Jamil ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Breakdown Voltage ◽  
Palm Oil ◽  
Pour Point ◽  
Electrical Breakdown ◽  
Dissipation Factor ◽  
Mineral Oil ◽  
Flash Point ◽  
Effect Of Water ◽  
Insulating Liquid

This paper describes the properties of refined, bleached, deodorized palm oil (RBDPO) as having the potential to be used as insulating liquid. There are several important properties such as electrical breakdown, dielectric dissipation factor, specific gravity, flash point, viscosity and pour point of RBDPO that was measured and compared to commercial mineral oil which is largely in current use as insulating liquid in power transformers. Experimental results of the electrical properties revealed that the average breakdown voltage of the RBDPO sample, without the addition of water at room temperature, is 13.368 kV. The result also revealed that due to effect of water, the breakdown voltage is lower than that of commercial mineral oil (Hyrax). However, the flash point and the pour point of RBDPO is very high compared to mineral oil thus giving it advantageous possibility to be used safely as insulating liquid. The results showed that RBDPO is greatly influenced by water, causing the breakdown voltage to decrease and the dissipation factor to increase; this is attributable to the high amounts of dissolved water.

scholarly journals Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5084
Author(s):  
Mardhiah Hayati Abdul Hamid ◽  
Mohd Taufiq Ishak ◽  
Nur Sabrina Suhaimi ◽  
Jaafar Adnan ◽  
Nazrul Fariq Makmor ◽  
...  
Keyword(s):  
Weibull Distribution ◽  
Electric Fields ◽  
Breakdown Voltage ◽  
Rice Bran ◽  
Rice Bran Oil ◽  
Transformer Oil ◽  
Uniform Field ◽  
Testing Methods ◽  
Lightning Impulse ◽  
The Difference

Transformer oil does not only serve as an insulating liquid, but also in removing heat from the windings and cores. Mineral oil (MO) has been widely used in transformers for more than 150 years. Recently, researchers have attempted to search for alternative insulating oils due to the possibility that MO will run out in the future together with the concern on fire safety and environmental pollution. Among the potential oils is rice bran oil (RBO). This work presents the studies of the lightning impulse (LI) of RBO behavior under various electric fields, gap distances and testing methods. The electrical performances of LI tests show that RBO and Palm Oil (PO) have lower LI breakdown voltage than MO under both uniform and non-uniform electric fields. However, the difference in LI breakdown voltages between RBO, PO and MO are slightly small which is less than 20%. In addition, there is no significant effect in the various testing methods under both uniform field and non-uniform field where the percentages of difference are less than 12% and 8% respectively. The data of LI breakdown voltage were statistically analysed to predict the withstand voltage and 50% breakdown voltage of oil samples by using Weibull distribution. The Weibull distribution of MO, PO and RBO has well fit with the fitting line. Finally, the relationship between LI voltages under a non-uniform field with various parameters of PO and RBO was obtained and proposed. From this work, it can be concluded that RBO shows promising results to be considered as an alternative to MO in transformer applications.

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