Jan Subocz - Academia.edu (original) (raw)
Papers by Jan Subocz
Energies
This paper presents the dielectric response of the insulation of bushings as an effect of the sim... more This paper presents the dielectric response of the insulation of bushings as an effect of the simulated long-term aging process. The experiment was conducted under a condition of a high temperature difference between the current circuit and the cover. The dielectric response was measured with the FDS (Frequency Dielectric Spectroscopy) and the SVM (Step Voltage Measurement) methods. The research has shown the correlation between the aging time and some parameters obtained with the FDS and SVM analysis.
Applied Sciences
In electric power systems, health index algorithms are mostly used for evaluation of the transfor... more In electric power systems, health index algorithms are mostly used for evaluation of the transformer population. In this method, some assessment criteria are insensitive when it comes to judging the technical state of the edges of the age spectrum. This paper presents a new health index calculation method that aims to improve the overall effectiveness of the assessment. The proposed algorithm is based on regularly conducted oil diagnostics and easily available maintenance data to enable estimation and updating of the device’s health status in short intervals from an operational point of view. This method is compared to another health index algorithm built from the same parameters, but with different weights and an alternative result assessment philosophy. The two health index calculation methods are tested on a population of 96 power transformers and then compared to results obtained with an expert system, which is based on much more advanced diagnostic tests to determine the techni...
Nanomaterials
In this paper, the electrical and thermal conductivity and morphological behavior of low density ... more In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures.
Croatica Chemica Acta
ABSTRACT
IEEE Transactions on Dielectrics and Electrical Insulation, 2015
Colloid and Polymer Science, 2014
In the reaction of 4,4′-methylenebis(phenyl isocyanate), polycaprolactone diol, and N-methyldieth... more In the reaction of 4,4′-methylenebis(phenyl isocyanate), polycaprolactone diol, and N-methyldiethanolamine, they were synthesized aqueous dispersions of polyurethane cationomers, from which films were prepared after adding 0-2 wt% graphene. In order to obtain nanocomposites, graphene was previously noncovalent functionalized in tetrahydrofurane in the field of ultrasound. The chemical structure and the morphology of obtained nanocomposites were analyzed by IR spectroscopy, atomic force microscopy (AFM), and differential scanning calorimetry (DSC) microcalorimetry methods. It was found that the presence of graphene results in increased thermal and mechanical strength of received polymer films and contributes to the increase in hydrophobicity of generally hydrophilic coatings prepared from waterborne polyurethane cationomers. Based on received results, possible interactions between graphene and phase structure of polyurethane cationomers were discussed. Relating to the so far described applications of graphene for the modification of polyurethanes, the novelty of this work is the concept of incorporation of graphene particles to polyurethane cationomer chains exclusively through a simple noncovalent functionalization and to investigate the effect of graphene on the properties obtained in this way of thin polyurethane film.
IEEE Transactions on Dielectrics and Electrical Insulation, 2014
ABSTRACT
Cellulose, 2015
This article presents results on the DC conductivity of moist pressboard impregnated with insulat... more This article presents results on the DC conductivity of moist pressboard impregnated with insulating oil and its dependence on the moisture and temperature of the samples. The transfer of charges was found to take place because of electron hopping between potential wells produced by water nanodrops. The average dimension of the nanodrops was around 2.32 nm, forming approximately 220 water molecules.
2014 ELEKTRO, 2014
ABSTRACT
ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132), 1998
It is shown that a prolonged sample of PET containing a metallocene compound forming by means of ... more It is shown that a prolonged sample of PET containing a metallocene compound forming by means of electric field of several hours duration results in additional structural effects that are not well investigated as yet. A similar problem was also encountered at TSC measurements in polyimide and polystyrene films. This problem calls for further investigation when taking into account the possibility the film may be employed in the presence of a strong electric field and high temperatures
ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117), 2001
ABSTRACT
2014 ELEKTRO, 2014
ABSTRACT The article presents the results of research based on the DC electrical conductivity of ... more ABSTRACT The article presents the results of research based on the DC electrical conductivity of wet paper depending on the moisture content and temperature of the samples. The change of moisture content does not change the activation energy of conductivity. The conductivity is performed by the hopping mechanism between the nearest possible holes which are formed in the material with nanodrops of water by the plotting of theoretical dependence that accurately describes the dependence of the conductivity of the water content and temperature. Medium size of nanodrops was about 1.5 nm, and the composition contains about 220 molecules of water.
ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117), 2001
ABSTRACT
10th International Symposium on Electrets (ISE 10). Proceedings (Cat. No.99 CH36256), 1999
ABSTRACT
Polymer Degradation and Stability, 1989
Energies
This paper presents the dielectric response of the insulation of bushings as an effect of the sim... more This paper presents the dielectric response of the insulation of bushings as an effect of the simulated long-term aging process. The experiment was conducted under a condition of a high temperature difference between the current circuit and the cover. The dielectric response was measured with the FDS (Frequency Dielectric Spectroscopy) and the SVM (Step Voltage Measurement) methods. The research has shown the correlation between the aging time and some parameters obtained with the FDS and SVM analysis.
Applied Sciences
In electric power systems, health index algorithms are mostly used for evaluation of the transfor... more In electric power systems, health index algorithms are mostly used for evaluation of the transformer population. In this method, some assessment criteria are insensitive when it comes to judging the technical state of the edges of the age spectrum. This paper presents a new health index calculation method that aims to improve the overall effectiveness of the assessment. The proposed algorithm is based on regularly conducted oil diagnostics and easily available maintenance data to enable estimation and updating of the device’s health status in short intervals from an operational point of view. This method is compared to another health index algorithm built from the same parameters, but with different weights and an alternative result assessment philosophy. The two health index calculation methods are tested on a population of 96 power transformers and then compared to results obtained with an expert system, which is based on much more advanced diagnostic tests to determine the techni...
Nanomaterials
In this paper, the electrical and thermal conductivity and morphological behavior of low density ... more In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures.
Croatica Chemica Acta
ABSTRACT
IEEE Transactions on Dielectrics and Electrical Insulation, 2015
Colloid and Polymer Science, 2014
In the reaction of 4,4′-methylenebis(phenyl isocyanate), polycaprolactone diol, and N-methyldieth... more In the reaction of 4,4′-methylenebis(phenyl isocyanate), polycaprolactone diol, and N-methyldiethanolamine, they were synthesized aqueous dispersions of polyurethane cationomers, from which films were prepared after adding 0-2 wt% graphene. In order to obtain nanocomposites, graphene was previously noncovalent functionalized in tetrahydrofurane in the field of ultrasound. The chemical structure and the morphology of obtained nanocomposites were analyzed by IR spectroscopy, atomic force microscopy (AFM), and differential scanning calorimetry (DSC) microcalorimetry methods. It was found that the presence of graphene results in increased thermal and mechanical strength of received polymer films and contributes to the increase in hydrophobicity of generally hydrophilic coatings prepared from waterborne polyurethane cationomers. Based on received results, possible interactions between graphene and phase structure of polyurethane cationomers were discussed. Relating to the so far described applications of graphene for the modification of polyurethanes, the novelty of this work is the concept of incorporation of graphene particles to polyurethane cationomer chains exclusively through a simple noncovalent functionalization and to investigate the effect of graphene on the properties obtained in this way of thin polyurethane film.
IEEE Transactions on Dielectrics and Electrical Insulation, 2014
ABSTRACT
Cellulose, 2015
This article presents results on the DC conductivity of moist pressboard impregnated with insulat... more This article presents results on the DC conductivity of moist pressboard impregnated with insulating oil and its dependence on the moisture and temperature of the samples. The transfer of charges was found to take place because of electron hopping between potential wells produced by water nanodrops. The average dimension of the nanodrops was around 2.32 nm, forming approximately 220 water molecules.
2014 ELEKTRO, 2014
ABSTRACT
ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132), 1998
It is shown that a prolonged sample of PET containing a metallocene compound forming by means of ... more It is shown that a prolonged sample of PET containing a metallocene compound forming by means of electric field of several hours duration results in additional structural effects that are not well investigated as yet. A similar problem was also encountered at TSC measurements in polyimide and polystyrene films. This problem calls for further investigation when taking into account the possibility the film may be employed in the presence of a strong electric field and high temperatures
ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117), 2001
ABSTRACT
2014 ELEKTRO, 2014
ABSTRACT The article presents the results of research based on the DC electrical conductivity of ... more ABSTRACT The article presents the results of research based on the DC electrical conductivity of wet paper depending on the moisture content and temperature of the samples. The change of moisture content does not change the activation energy of conductivity. The conductivity is performed by the hopping mechanism between the nearest possible holes which are formed in the material with nanodrops of water by the plotting of theoretical dependence that accurately describes the dependence of the conductivity of the water content and temperature. Medium size of nanodrops was about 1.5 nm, and the composition contains about 220 molecules of water.
ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117), 2001
ABSTRACT
10th International Symposium on Electrets (ISE 10). Proceedings (Cat. No.99 CH36256), 1999
ABSTRACT
Polymer Degradation and Stability, 1989