scholarly journals The Impact of TiO2 Nanoparticle Concentration Levels on Impulse Breakdown Performance of Mineral Oil-Based Nanofluids

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 627 ◽  
Author(s):  
Ziyi Wang ◽  
You Zhou ◽  
Wu Lu ◽  
Neng Peng ◽  
Weijie Chen
Keyword(s):  
Tio2 Nanoparticles ◽  
Electric Fields ◽  
Breakdown Voltage ◽  
Concentration Level ◽  
Breakdown Strength ◽  
Mineral Oil ◽  
Interfacial Region ◽  
Bulk Oil ◽  
Lightning Impulse ◽  
The Impact

The insulation of mineral oil-based nanofluids was found to vary with different concentration level of nanoparticles. However, the mechanisms behind this research finding are not well studied. In this paper, mineral oil-based nanofluids were prepared by suspending TiO2 nanoparticles with weight percentages ranging from 0.0057% to 0.0681%. The breakdown voltage and chop time of nanofluids were observed under standard lightning impulse waveform. The experimental results show that the presence of TiO2 nanoparticles increases the breakdown voltage of mineral oil under positive polarity. The enhancement of breakdown strength tends to saturate when the concentration of nanoparticle exceeds 0.0227 wt%. Electronic traps formed at the interfacial region of nanoparticles, which could capture fast electrons in bulk oil and reduce the net density of space charge in front of prebreakdown streamers, are responsible for the breakdown strength enhancement. When the particle concentration level is higher, the overlap of Gouy–Chapman diffusion layers results in the saturation of trap density in nanofluids. Consequently, the breakdown strength of nanofluids is saturated. Under negative polarity, the electrons are likely to be scattered by the nanoparticles on the way towards the anode, resulting in enhanced electric fields near the streamer tip and the decrement of breakdown voltage.

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.

scholarly journals Improvement of DC Breakdown Strength of the Epoxy/POSS Nanocomposite by Tailoring Interfacial Electron Trap Characteristics

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1298
Author(s):  
Farooq Aslam ◽  
Zhen Li ◽  
Guanghao Qu ◽  
Yang Feng ◽  
Shijun Li ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Breakdown Voltage ◽  
Breakdown Strength ◽  
Deep Level ◽  
Simulation Method ◽  
Neat Epoxy ◽  
Interfacial Region ◽  
Chemical Calculation ◽  
Oligomeric Silsesquioxane ◽  
Underlying Risk

To date, breakdown voltage is an underlying risk to the epoxy-based electrical high voltage (HV) equipment. To improve the breakdown strength of epoxy resin and to explore the formation of charge traps, in this study, two types of polyhedral oligomeric silsesquioxane (POSS) fillers are doped into epoxy resin. The breakdown voltage test is performed to investigate the breakdown strength of neat epoxy and epoxy/POSS composites. Electron traps that play an important role in breakdown strength are characterized by thermally stimulated depolarized current (TSDC) measurement. A quantum chemical calculation tool identifies the source of traps. It is found that adding octa-glycidyl POSS (OG-POSS) to epoxy enhances the breakdown strength than that of neat epoxy and epoxycyclohexyl POSS (ECH-POSS) incorporated epoxy. Moreover, side groups of OG-POSS possess higher electron affinity (EA) and large electronegativity that introduces deep-level traps into epoxy resin and restrain the electron transport. In this work, the origin of traps has been investigated by the simulation method. It is revealed that the functional properties of POSS side group can tailor an extensive network of deep traps in the interfacial region with epoxy and enhance the breakdown strength of the epoxy/POSS nanocomposite.

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.

scholarly journals Behavior of Biodegradable Oil under Impulse Voltages

2015 ◽  
Vol 785 ◽  
pp. 320-324 ◽  
Author(s):  
Nurul Izzatul Akma Katim ◽  
Mohd Taufiq Ishak ◽  
A.M. Ishak ◽  
M.Z.A.A. Kadir
Keyword(s):  
Breakdown Voltage ◽  
Palm Oil ◽  
Coconut Oil ◽  
Mineral Oil ◽  
Electrical Performance ◽  
Uniform Field ◽  
Testing Methods ◽  
Environmental Compatibility ◽  
Impulse Voltage ◽  
Lightning Impulse

The properties of Palm Oil (PO) and Coconut Oil (CO) offer the potential for transformers with non-toxicity, high fire and flash points and better environmental compatibility while compared with those filled with Mineral Oil (MO). This potential has led to intensive studies of electrical performance of biodegradable oil especially in evaluating the electrical performance under lightning impulse voltage in recent years. This paper presents the investigation on the impulse breakdown voltage of PO and CO in such a uniform field. The PO used in this study is Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein type. Two testing methods, rising-voltage and up-and-down are considered for both oils with different gap distances (2.0 mm and 3.8 mm). Testing methods including rising-voltage method and up-and-down method have no notable influence on the breakdown voltages of RBDPOs and CO compared to MO.

scholarly journals A Promising Nano-Insulating-Oil for Industrial Application: Electrical Properties and Modification Mechanism

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 788 ◽  
Author(s):  
Jiaqi Chen ◽  
Potao Sun ◽  
Wenxia Sima ◽  
Qianqiu Shao ◽  
Lian Ye ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Industrial Application ◽  
Breakdown Strength ◽  
Absorption Capacity ◽  
Photon Absorption ◽  
Electrical Performance ◽  
Test Results ◽  
Strong Electron ◽  
Insulating Oil ◽  
Lightning Impulse

Despite being discovered more than 20 years ago, nanofluids still cannot be used in the power industry. The fundamental reason is that nano-insulating oil has poor stability, and its electrical performance decreases under negative impulse voltage. We found that C60 nanoparticles can maintain long-term stability in insulating oil without surface modification. C60 has strong electronegativity and photon absorption ability, which can comprehensively improve the electrical performance of insulating oil. This finding has great significance for the industrial application of nano-insulating oil. In this study, six concentrations of nano-C60 modified insulating oil (CMIO) were prepared, and their breakdown strength and dielectric properties were tested. The thermally stimulated current (TSC) curves of fresh oil (FO) and CMIO were experimentally determined. The test results indicate that C60 nanoparticles can simultaneously improve the positive and negative lightning impulse and power frequency breakdown voltage of insulating oil, while hardly increasing dielectric loss. At 150 mg/L, the positive and negative lightning impulse breakdown voltages of CMIO increased by 7.51% and 8.33%, respectively, compared with those of FO. The AC average breakdown voltage reached its peak (18.0% higher compared with FO) at a CMIO concentration of 200 mg/L. Based on the test results and the special properties of C60, we believe that changes in the trap parameters, the strong electron capture ability of C60, and the absorption capacity of C60 for photons enhanced the breakdown performance of insulating oil by C60 nanoparticles.

Breakdown Strength Characteristic of RBDPO and Mineral Oil Mixture as an Alternative Insulating Liquid for Transformer

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Yusnida M. ◽  
Kiasatina Azmi ◽  
Mohd Azmier Ahmad ◽  
Zulkifli Ahmad ◽  
Mohamad Kamarol
Keyword(s):  
Breakdown Voltage ◽  
Strength Characteristic ◽  
Palm Oil ◽  
Kinematic Viscosity ◽  
Breakdown Strength ◽  
Environmental Concern ◽  
Mineral Oil ◽  
Electrical Insulation ◽  
Insulating Oil ◽  
Insulating Liquid

Mineral oil (MO) works as an important electrical insulation and coolant in transformer which is non-biodegradable and nearly running out. Therefore, for sustainable and environmental concern, an alternative biodegradable insulating oil that potential to replace the mineral oil is introduced. In view of that, the breakdown strength characteristic of Refined Bleached Deodorized Palm Oil (RBDPO) and MO mixtures were investigated by varying the mixing percentage of RBDPO from 0% to 100% at 40oC. The results showed that the breakdown strength of the oil mixture abruptly decline to the minimum breakdown voltage of 50 kV at  20% of  RBDPO mixture and gradually increased when  the ratio of the RBDPO is added. The highest breakdown strength is achieved 87kv at 80% of RBDPO content. The result of kinematic viscosity is also presented.

Investigation on Voltage Breakdown of Natural Ester Oils Based-On Zno Nanofluids

2015 ◽  
Vol 1119 ◽  
pp. 175-178 ◽  
Author(s):  
Wittawat Saenkhumwong ◽  
Amnart Suksri
Keyword(s):  
Power System ◽  
Breakdown Voltage ◽  
Palm Oil ◽  
Breakdown Strength ◽  
Mineral Oil ◽  
Transformer Oil ◽  
Slow Process ◽  
Zno Nanofluids ◽  
Voltage Breakdown ◽  
Natural Ester

Transformer is one of the major component, which is the most important device in power system. Their lifetime depends upon liquid insulation that help transfer the heat out of its winding inside of transformer. Transformer oil uses mineral oil that is the most commonly used has very slow process on decomposition and non-biodegrade. This paper presents the investigation on breakdown voltage of two types of natural ester oils, including palm oil and soy bean based-on ZnO nanofluids. Nanofluids that use nanoparticles modified by use of surfactant that are suspended by process of sonication. Different fraction of nanoparticles were investigated from 0.1% - 0.5% by weight. The breakdown voltage were measured according to ASTM D877. The voltage breakdown strength increased significantly when nanoparticles were added in oils. The obtained results will enable transformer industry to develop liquid insulation dielectric for use in transformer in the future.

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.

Self-Clearing of Metalized Electrodes and its Impact on Electroactive Polymer (EAP) Based Actuators

2016 ◽  
Author(s):  
Saad Ahmed ◽  
Zoubeida Ounaies
Keyword(s):  
Electric Fields ◽  
Intelligent Systems ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Control Sample ◽  
Dielectric Medium ◽  
Practical Implementation ◽  
Current Path ◽  
Electromechanical Performance ◽  
The Impact

EAP based actuator technologies are extensively studied to design smart/intelligent systems ranging from deployable space structures, morphing wings, to medical devices and artificial muscles. Despite the extensive research on electroactive polymers (EAP), practical implementation of this technology is slow because of low induced forces and defect-driven premature electrical breakdown. Multilayered or stacked configuration can address the low induced force issue. However, construction procedure of multilayered sample is susceptible to more defects, which can further aggravate defect-driven premature breakdown of EAP actuators. Reducing the number of defects using self-clearing concept can improve the EAP actuators’ ability to withstand high electric fields. Self-clearing refers to the partial local breakdown of dielectric medium due to the presence of impurities, which in turn results in the evaporation of some of the metalized electrodes. After this evaporation, the impurity is cleared and any current path would be safely cut off, which means the actuator continues to perform, albeit with a reduced actuation area due to electrode evaporation. In this paper we study the impact of self-clearing metalized silver electrodes on the electrical and electromechanical behavior of EAPs, more specifically P(VDF-TrFE-CTFE) terpolymer. First, we use Weibull statistics to systematically estimate the self-clearing/preconditioning field needed to clear the defects. Then electrical breakdown experiments are conducted with and without preconditioning the samples to investigate their effects on the breakdown strength of the EAP. Finally, we implement this self-clearing/preconditioning field on single and multilayered P (VDF-TrFE-CTFE) unimorph actuators and investigate the resulting electromechanical performance. Due to preconditioning of the actuators using self-clearing concept, the actuators endure higher electric fields compared to a control sample. Loss of capacitance occurs during self-clearing, which in turn affects the electromechanical performance of the actuator. For that reason, we also report on the blocked force of preconditioned and controlled actuators to evaluate and compare their electromechanical performance.

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