scholarly journals The Influence of Nanoparticles’ Conductivity and Charging on Dielectric Properties of Ester Oil Based Nanofluid

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6540
Author(s):  
Konstantinos N. Koutras ◽  
Ioannis A. Naxakis ◽  
Eleftheria C. Pyrgioti ◽  
Vasilios P. Charalampakos ◽  
Ioannis F. Gonos ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Partial Discharge ◽  
Al2o3 Nanoparticles ◽  
Sic Nanoparticles ◽  
Base Oil ◽  
Dielectric Performance ◽  
Lightning Impulse ◽  
The Stability ◽  
Inception Voltage ◽  
Natural Ester

This study addresses the effect of nanoparticles’ conductivity and surface charge on the dielectric performance of insulating nanofluids. Dispersions of alumina and silicon carbide nanoparticles of similar size (~50 nm) and concentration (0.004% w/w) were prepared in natural ester oil. The stability of the dispersions was explored by dynamic light scattering. AC, positive and negative lightning impulse breakdown voltage, as well as partial discharge inception voltage of the nanofluid samples were measured and compared with the respective properties of the base oil. The obtained results indicate that the addition of SiC nanoparticles can lead to an increase in AC breakdown voltage and also enhance the resistance of the liquid to the appearance of partial discharge. On the other hand, the induction of positive charge from the Al2O3 nanoparticles could be the main factor leading to an improved positive Lightning Impulse Breakdown Voltage and worse performance at negative polarity.

Moisture effects on AC dielectric strength and partial discharge inception voltage in natural monoesters

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Emeric Tchamdjio Nkouetcha ◽  
Ghislain Mengata Mengounou ◽  
Adolphe Moukengue Imano
Keyword(s):  
Water Contamination ◽  
Partial Discharge ◽  
Palm Kernel ◽  
Dielectric Strength ◽  
Glycerol Solution ◽  
Humid Environment ◽  
Insulating Liquids ◽  
Moisture Effects ◽  
Dielectric Performance ◽  
Inception Voltage

Abstract It is essential to analyse the dielectric performance in a humid environment of insulating liquids of plant origin, considered as alternatives to mineral oil (MO) which is not environmentally friendly. This paper focuses on the effects of different moisture levels on the dielectric strength and partial discharge initiation voltage of two natural monoesters, based on castor oil (CO) and palm kernel oil (PKO), and MO. The different samples were moistened with a glycerol solution, then sealed and stored for 12 days to allow further diffusion of moisture into the samples. Dielectric strength was statistically evaluated from IEC 60156. Partial discharge inception voltage (PDIV) experiment was performed in conformity with a modified IEC 61294 purpose at ambient temperature. Based on the experimental observations, the moisture has different behavior on dielectric strength and PDIV of insulating oils. Monoesters have a better withstand to water contamination than MOs in power transformers.

scholarly journals Study on Partial Discharge Characteristics of C6F12O Mixed Gas

2021 ◽  
Author(s):  
Xiajin Rao ◽  
Dajian Li ◽  
Xiaofei Xia ◽  
Yi Su ◽  
Yufeng Lu ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Low Voltage ◽  
Partial Discharge ◽  
Buffer Gas ◽  
Mixing Ratio ◽  
Mixed Gas ◽  
Discharge Characteristics ◽  
Power Frequency ◽  
The Difference ◽  
Inception Voltage

Abstract The greenhouse effect of SF6 increasingly limits its application in various gas insulated equipment. C6F12O combines the advantages of insulation resistance, safety and environmental protection. When mixed with buffer gas, C6F12O is considered to have potential application prospects in medium and low voltage equipment. In this paper, about the partial discharge characteristics of the mixed gas, an experimental study was carried out. The partial discharge initiation voltage and discharge extinction voltage of mixed gas under power frequency voltage are measured and compared with the breakdown voltage. The results show that with the increase of mixing ratio, the partial discharge initiation voltage and extinction voltage of mixed gas gradually increase, and the effect of gas pressure on high mixing ratio is obvious. The difference between the partial discharge inception voltage and the breakdown voltage is larger than that of pure N2. The research in this paper can provide an important reference for the application, operation and protection of C6F12O mixed gas in medium and low voltage equipment.

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.

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