Mechanism behind Increasing Electrostatic Charging Tendency in Aged Mineral-Oil-Immersed Pressboards

Comparative study of the electrostatic charging tendency between synthetic ester and mineral oil

IEEE Transactions on Dielectrics and Electrical Insulation ◽

10.1109/tdei.2013.6633689 ◽

2013 ◽

Vol 20 (5) ◽

pp. 1598-1606 ◽

Cited By ~ 14

Author(s):

M. Talhi ◽

I. Fofana ◽

S. Flazi

Keyword(s):

Comparative Study ◽

Mineral Oil ◽

Synthetic Ester ◽

Electrostatic Charging

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Electrostatic Charging Tendency Analysis Concerning Retrofilling Power Transformers with Envirotemp FR3 Natural Ester

Energies ◽

10.3390/en13174420 ◽

2020 ◽

Vol 13 (17) ◽

pp. 4420 ◽

Cited By ~ 1

Author(s):

Maciej Zdanowski

Keyword(s):

Mineral Oil ◽

Volume Density ◽

Point Of View ◽

Pipe Material ◽

Mineral Oils ◽

Insulating Liquids ◽

Electrostatic Charging ◽

Tendency Analysis ◽

Insulating Liquid ◽

Natural Ester

Natural and synthetic esters are liquids characterized by insulating properties, high flash point, and biodegradability. For this reason, they are more and more often used as an alternative to conventional mineral oils. Esters are used to fill new or operating transformers previously filled with mineral oil (retrofilling). It is technically unfeasible to completely remove mineral oil from a transformer. Its small residues create with esters a mixture with features significantly different from those of the base liquids. This article presents electrostatic charging tendency (ECT) tests for mixtures of fresh and aged Trafo EN mineral oil with Envirotemp FR3 natural ester from the retrofilling point of view. Under unfavorable conditions, the flow electrification phenomenon can damage the solid insulation in transformers with forced oil circulation. The ECT of the insulating liquids has been specified using the volume density of the qw charge. This parameter has been determined using the Abedian–Sonin model on the basis of the electrification current measured in the flow system, as well as selected physicochemical properties of the liquids. It was shown that ECT is strongly dependent on the type of insulating liquid and pipe material, as well as the composition of the mixtures. The most important finding from the research is that a small amount (up to 10%) of fresh and aged mineral oil is effective in reducing the ECT of Envirotemp FR3 natural ester.

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Comparison of electrostatic charging tendency of Jarylec and mineral oil

Electrical Engineering ◽

10.1007/s00202-021-01400-8 ◽

2021 ◽

Author(s):

Abderrahmane Beroual ◽

Hocine Khelifa ◽

Usama Khaled

Keyword(s):

Mineral Oil ◽

Electrostatic Charging

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Attractive mode force microscopy of chiral liquid crystal surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121740 ◽

1992 ◽

Vol 50 (1) ◽

pp. 268-269

Author(s):

B.D. Terris ◽

R. J. Twieg ◽

C. Nguyen ◽

G. Sigaud ◽

H. T. Nguyen

Keyword(s):

Liquid Crystal ◽

Crystal Surfaces ◽

Free Surfaces ◽

Control Range ◽

Force Microscopy ◽

Liquid Crystal Films ◽

Chiral Liquid Crystal ◽

Crystal Films ◽

Electrostatic Charging ◽

And Shifts

We have used a force microscope in the attractive, or noncontact, mode to image a variety of surfaces. In this mode, the microscope tip is oscillated near its resonant frequency and shifts in this frequency due to changes in the surface-tip force gradient are detected. We have used this technique in a variety of applications to polymers, including electrostatic charging, phase separation of ionomer surfaces, and crazing of glassy films.Most recently, we have applied the force microscope to imaging the free surfaces of chiral liquid crystal films. The compounds used (Table 1) have been chosen for their polymorphic variety of fluid mesophases, all of which exist within the temperature control range of our force microscope.

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