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Papers by antonio mandala

Research paper thumbnail of Evaluation of the Aging of Oil‐Paper Insulation Using an Improved Fractional Poynting‐Thomson Model

IEEJ Transactions on Electrical and Electronic Engineering

Assessment of the aging of oil‐paper insulation is analyzed in this article, based on an improved... more Assessment of the aging of oil‐paper insulation is analyzed in this article, based on an improved fractional Poynting‐Thomson model, which includes dc and hopping conductivity (P‐T model2). Based on samples of oil paper produced in laboratories with different thermal aging times, it has been found that the proposed improved model provides a better fit and a higher index of coincidence concerning the measured values than the traditional P‐T model and the model that only incorporates the effect of dc conductivity (P‐T model1). Nevertheless, comparing the proposed improved P‐T model with the traditional Cole–Cole (C‐C), Davidson–Cole (D‐C), and Havriliak–Negami (H‐N) models, the improved P‐T model2 also demonstrated a superior fit for the measured value and a higher coincidence index than another model. In addition, there was an excellent exponential relationship between the quantities εa, εb and τ of the improved model and the furfural content of the samples. Consequently, these chara...

Research paper thumbnail of The Dielectric Voltage Response Characteristics of Transformer Oil–Paper Insulation and Its Aging State Assessment

MAPAN

The dielectric voltage response characteristics of transformer oil–paper insulation are closely r... more The dielectric voltage response characteristics of transformer oil–paper insulation are closely related to aging and moisture. Polarization voltage rate and degradation voltage rate can be used to evaluate insulation aging and moisture, respectively, but it takes a long time to acquire the above two characteristics. In this paper, the dielectric voltage response characteristic of transformer oil–paper insulation was measured by a single charge and multiple discharge method. The change rule of its initial slope characteristic was analyzed based on the relationship between the attenuation amplitude of dielectric polarization intensity reflected by the equivalent circuit and the initial slope of dielectric voltage response. The cumulative sum of initial slopes of dielectric voltage response ( S ) is proposed to evaluate the aging state of transformer oil–paper insulation. At the same time, the corresponding relationship between the characteristic quantity S and the content of furfural ( C k ) in oil is studied experimentally. The results show that with the increase of insulation aging degree, both C k and S increase. The fitting results show that the proposed characteristic quantity S and C k have a linear relationship suitable for quantitative analysis of the insulation aging state.

Research paper thumbnail of An Improved Mathematical Model for Estimating Polarization Parameters of Transformer Oil-Paper Insulation

Research paper thumbnail of Identification of extended Debye model parameters for oil-paper insulation based on voltage response characteristic

Research paper thumbnail of Analysis of Dielectric Response Measurements for Condition Assessment of Oil-Paper in Power Transformer Insulation

In this paper, the oil-paper insulation system of the power transformer is analyzed in the freque... more In this paper, the oil-paper insulation system of the power transformer is analyzed in the frequency domain. Different factors that influence the dielectric insulation of oilpaper, such as the temperature, moisture in cellulose, conductivity, and oil aging, are described. The analysis for the dielectric response is carried out by analyzing the dissipation factors and the complex capacitance through the Frequency Domain Spectroscopy (FDS) method. This tool analyzes the dielectric responses of the oil-paper insulation system, by measuring a series of dissipation factors at different frequencies, typically distributed over the range of 0.001 Hz to 1000 Hz. The result of the experiments shows that the temperatures, moisture in cellulose, conductivity, and oil aging have a significant influence, in the low-frequency range than in the high-frequency range.

Research paper thumbnail of Evaluation of the Aging of Oil‐Paper Insulation Using an Improved Fractional Poynting‐Thomson Model

IEEJ Transactions on Electrical and Electronic Engineering

Assessment of the aging of oil‐paper insulation is analyzed in this article, based on an improved... more Assessment of the aging of oil‐paper insulation is analyzed in this article, based on an improved fractional Poynting‐Thomson model, which includes dc and hopping conductivity (P‐T model2). Based on samples of oil paper produced in laboratories with different thermal aging times, it has been found that the proposed improved model provides a better fit and a higher index of coincidence concerning the measured values than the traditional P‐T model and the model that only incorporates the effect of dc conductivity (P‐T model1). Nevertheless, comparing the proposed improved P‐T model with the traditional Cole–Cole (C‐C), Davidson–Cole (D‐C), and Havriliak–Negami (H‐N) models, the improved P‐T model2 also demonstrated a superior fit for the measured value and a higher coincidence index than another model. In addition, there was an excellent exponential relationship between the quantities εa, εb and τ of the improved model and the furfural content of the samples. Consequently, these chara...

Research paper thumbnail of The Dielectric Voltage Response Characteristics of Transformer Oil–Paper Insulation and Its Aging State Assessment

MAPAN

The dielectric voltage response characteristics of transformer oil–paper insulation are closely r... more The dielectric voltage response characteristics of transformer oil–paper insulation are closely related to aging and moisture. Polarization voltage rate and degradation voltage rate can be used to evaluate insulation aging and moisture, respectively, but it takes a long time to acquire the above two characteristics. In this paper, the dielectric voltage response characteristic of transformer oil–paper insulation was measured by a single charge and multiple discharge method. The change rule of its initial slope characteristic was analyzed based on the relationship between the attenuation amplitude of dielectric polarization intensity reflected by the equivalent circuit and the initial slope of dielectric voltage response. The cumulative sum of initial slopes of dielectric voltage response ( S ) is proposed to evaluate the aging state of transformer oil–paper insulation. At the same time, the corresponding relationship between the characteristic quantity S and the content of furfural ( C k ) in oil is studied experimentally. The results show that with the increase of insulation aging degree, both C k and S increase. The fitting results show that the proposed characteristic quantity S and C k have a linear relationship suitable for quantitative analysis of the insulation aging state.

Research paper thumbnail of An Improved Mathematical Model for Estimating Polarization Parameters of Transformer Oil-Paper Insulation

Research paper thumbnail of Identification of extended Debye model parameters for oil-paper insulation based on voltage response characteristic

Research paper thumbnail of Analysis of Dielectric Response Measurements for Condition Assessment of Oil-Paper in Power Transformer Insulation

In this paper, the oil-paper insulation system of the power transformer is analyzed in the freque... more In this paper, the oil-paper insulation system of the power transformer is analyzed in the frequency domain. Different factors that influence the dielectric insulation of oilpaper, such as the temperature, moisture in cellulose, conductivity, and oil aging, are described. The analysis for the dielectric response is carried out by analyzing the dissipation factors and the complex capacitance through the Frequency Domain Spectroscopy (FDS) method. This tool analyzes the dielectric responses of the oil-paper insulation system, by measuring a series of dissipation factors at different frequencies, typically distributed over the range of 0.001 Hz to 1000 Hz. The result of the experiments shows that the temperatures, moisture in cellulose, conductivity, and oil aging have a significant influence, in the low-frequency range than in the high-frequency range.