Determination of Dielectric Losses in a Power Transformer

Nadolny, Zbigniew

doi:10.3390/en15030993

Cited by 11 publications

(12 citation statements)

References 41 publications

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“…One of the properties hardly considered for the fundamental model analysis of liquid crystalline materials, including nanocolloids, is the tangent of the loss angle

, often recalled as

δ and defined as follows [ 72 , 103 , 104 , 105 , 106 , 107 , 108 ]:

where

is the current applied to the capacitance with the dielectric from the external source,

is the capacitance of the empty capacitor, and

is the applied voltage;

is associated with the presence of the dielectric in the capacitor and

is the loss current in the dielectric.…”

Section: Resultsmentioning

confidence: 99%

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Drozd-Rzoska,

Łoś,

Rzoska

2024

Nanomaterials

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The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4′–butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The ‘universal’ exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the ‘critical-like’ evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, ‘critical-like’ behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.

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“…One of the properties hardly considered for the fundamental model analysis of liquid crystalline materials, including nanocolloids, is the tangent of the loss angle

, often recalled as

δ and defined as follows [ 72 , 103 , 104 , 105 , 106 , 107 , 108 ]:

where

is the current applied to the capacitance with the dielectric from the external source,

is the capacitance of the empty capacitor, and

is the applied voltage;

is associated with the presence of the dielectric in the capacitor and

is the loss current in the dielectric.…”

Section: Resultsmentioning

confidence: 99%

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Drozd-Rzoska,

Łoś,

Rzoska

2024

Nanomaterials

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“…It is also possible to complete the extended Noyes-Whitney relation (Equation ( 4)) by determining the evolution of DC electric conductivity (Equation ( 16)). The possibilities mentioned here related to finding and characterizing supercritical changes in the dielectric constant in linseed oil may also have broader significance in other industrial applications of linseed oil [110][111][112][113][114][115][116][117], such as an 'ecological' transformer oil [110][111][112], for instance. They can use linseed oil as a qualitatively new and ecological supercritical carrier agent in innovative supercritical extraction or processing technologies.…”

Section: Discussionmentioning

confidence: 99%

“…The loss factor enables insight into dynamics via the energy dissipation associated with the relaxation process, namely [97][98][99][107][108][109][110][111][112]…”

Section: Unique Glassy Dynamicsmentioning

confidence: 99%

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Supercriticality, Glassy Dynamics, and the New Insight into Melting/Freezing Discontinuous Transition in Linseed Oil

Drozd-Rzoska,

Rzoska,

Łoś

2024

Biophysica

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The long-range supercritical changes of dielectric constant, resembling ones observed in the isotropic liquid phase of liquid crystalline compounds, are evidenced for linseed oil—although in the given case, the phenomenon is associated with the liquid–solid melting/freezing discontinuous phase transitions. This ‘supercriticality’ can be an additional factor supporting the unique pro-health properties of linseed oil. Broadband dielectric spectroscopy studies also revealed the ‘glassy’ changes of relaxation times, well portrayed by the ‘activated and critical’ equation recently introduced. In the solid phase, the premelting effect characteristic for the canonic melting/freezing discontinuous transition, i.e., without any pretransitional effect in the liquid phase, has been detected. It is interpreted within the grain model, and its parameterization is possible using the Lipovsky model and the ‘reversed’ Mossotti catastrophe concept. For the premelting effect in the solid state, the singular ‘critical’ temperature correlates with the bulk discontinuous melting and freezing temperatures. Consequently, the report shows that linseed oil, despite its ‘natural and complex’ origins, can be considered a unique model system for two fundamental problems: (i) pretransitional (supercritical) effects in the liquid state associated with a weakly discontinuous phase transition, and (ii) the premelting behavior in the solid side of the discontinuous melting/freezing discontinuous transition.

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“…Dielectric losses occur in the transformer isolation system. Their value does not exceed 1% of the total losses [6].…”

Section: Fundamentals Of Transformer Temperature Distribution 21 Heat...mentioning

confidence: 93%

The Tools and Parameters to Consider in the Design of Power Transformer Cooling Systems

Goscinski,

Nadolny,

Nawrowski

et al. 2023

Energies

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Transformers are the most important elements of electric power systems. Many conditions must be met for power transformers to work properly. One of them is a low operating temperature. This condition will be met if the transformer cooling system is properly designed. One of the components of a cooling system is insulating liquid. The heat transfer coefficient α of liquid determines its ability to cool the transformer. The higher its value, the more effectively the liquid transfers heat to the environment. This article describes the influence of the position of the heat source, which is usually in the windings of the transformer, on the coefficient α value of the insulating liquid. The vertical and horizontal positions of the heat source were analyzed. The coefficient α was analyzed at different points of the heat source. The tests were carried out for mineral oil and various esters. Heat transfer coefficient measurements were carried out for various surface heat loads of the heat source. It has been proven that, in the case of a horizontal heat source, the coefficient α has a value several dozen percent higher than in the case of a vertical source. It has been proven that the coefficient α has different values in different places of the heat source. Regardless of the location, the highest value of the coefficient α occurred in the lower part of the heat source.

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Determination of Dielectric Losses in a Power Transformer

Cited by 11 publications

References 41 publications

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Supercriticality, Glassy Dynamics, and the New Insight into Melting/Freezing Discontinuous Transition in Linseed Oil

The Tools and Parameters to Consider in the Design of Power Transformer Cooling Systems

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