Journal ArticleDOI
Electrothermal aging characteristics of epoxy resin under bipolar exponential decay pulse voltage and its insulation life evaluation based on Cole-Cole model
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TLDR
In this article, an electrothermal aging experiment of epoxy resin was carried out under bipolar exponential decay pulse voltages at high temperature using frequency-domain spectroscopy and the double-relaxation Cole-Cole model was used to fit the dielectric spectra.Abstract:
The epoxy resin insulation in saturable reactors in a HVDC transmission converter valve is subjected to a bipolar exponential decay pulse voltages under normal operating conditions and its aging mechanism is still unclear. In this paper, an electrothermal aging experiment of epoxy resin was carried out under bipolar exponential decay pulse voltages at high temperature. The dielectric properties of epoxy resin before and after aging were measured using frequency-domain spectroscopy. To quantitatively study the aging characteristics, the double-relaxation Cole-Cole model was used to fit the dielectric spectra. As a result, an exponential function relationship between the relaxation time constant and the aging time of epoxy resin under various aging conditions was obtained. This relationship can be used as an empirical formula to evaluate the degree of aging. Furthermore, a comparison of the aging life characteristics of epoxy resin under pulse and sinusoidal voltages with the same peak value was performed. The results show that the electrothermal aging rate of epoxy resin under a pulse voltage is lower than under a sinusoidal voltage. The effect of the measurement temperature on the insulation life evaluation of epoxy resin was also analyzed.read more
Citations
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Journal ArticleDOI
Sensing the Thermal Aging of Epoxy Alumina Nano-Composites Using Electric Modulus
TL;DR: In this article, a novel technique to accurately sense the thermal aging of the epoxy alumina nano-composites employing complex electric modulus is proposed, which is defined as the inverse of the complex permittivity.
Proceedings ArticleDOI
Dielectric Measurement using Planar and Curved Microstrip Line
TL;DR: In this article, a microwave transmission line sensor is investigated and used for bulk liquid permittivity measurement for a frequency range of 150 kHz to 8 GHz, where the sensor is implemented on a curved substrate instead of the traditional planar substrate.
Journal ArticleDOI
NSGA-II Model-Based Dielectric Frequency Response Parameters for Aging and Moisture Analysis of Transformer Insulation
TL;DR: In this paper , a combination of NSGA-II and extended Cole-Cole model is presented to extract the required feature parameters for transformer insulation state analysis, and an intelligent optimization model is reported to be responsible for more accurate and reliable state analysis of transformer insulation via the extracted feature parameters.
Journal ArticleDOI
Electrical Property of Polypropylene Films Subjected to Different Temperatures and DC Electric Fields.
TL;DR: In this paper, the effects of uniform as well as non-uniform electric fields were compared at the same temperature for the polypropylene (PP) film, and experimental results indicated that the time-to-breakdown of all PP films, plain or filled with nano-clay, decreases with the increase in electric field intensity, nonuniformity of the electric field, and temperature.
A Novel Approach to Estimate Electrothermal Aging of Epoxy–Alumina Nanocomposites Using Dielectric Relaxation Current Analysis
TL;DR: In this article , an advanced technique is applied to estimate the aging state of epoxy-alumina nanocomposite insulation, and two empirical relationships are proposed based on the experimental investigation.
References
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Journal ArticleDOI
Dispersion and Absorption in Dielectrics I. Alternating Current Characteristics
Kenneth S. Cole,Robert H. Cole +1 more
TL;DR: In this paper, the locus of the dielectric constant in the complex plane was defined to be a circular arc with end points on the axis of reals and center below this axis.
Journal ArticleDOI
Dispersion and Absorption in Dielectrics II. Direct Current Characteristics
Kenneth S. Cole,Robert H. Cole +1 more
TL;DR: In this paper, it was shown that the complex dielectric constant, e*, of many liquid and solid dielectrics is given by a single very general formula e*=e∞+(e0−e ∞)/[1+(iωτ0)1−α] In this equation e0 and e∞ are the ''static'' and ''infinite frequency'' dielectoric constants, ω = 2π times the frequency, τ 0 is a generalized relaxation time and α is a constant, 0 < α < 1 The transient current as a
Journal ArticleDOI
Investigations of Temperature Effects on the Dielectric Response Measurements of Transformer Oil-Paper Insulation System
TL;DR: In this paper, the effects of temperature on the dielectric measurements of a transformer under controlled laboratory conditions are investigated, and the results of practical on-site testing are also presented to demonstrate the possibility of errors that may be introduced in dielectrics test results analysis unless temperature effects are taken into consideration.
Journal ArticleDOI
On the frequency domain dielectric response of oil-paper insulation at low temperatures
Issouf Fofana,H. Hemmatjou,F. Meghnefi,Masoud Farzaneh,A. Setayeshmehr,Hossein Borsi,Ernst Gockenbach +6 more
TL;DR: In this article, the dielectric behavior of a composite oil paper insulation system has been explained from the properties of the Debye basic model, and the equivalent circuit parameters of a laboratory made oil paper condenser bushing model were obtained using a nonlinear optimization procedure.
Journal ArticleDOI
Quantitative analysis of ageing condition of oil-paper insulation by frequency domain spectroscopy
TL;DR: In this article, a frequency domain spectroscopy (FDS) was used to assess the ageing condition of oil-paper insulation used in transformers, and the results reveal that the relative permittivity (er') plots of oil impregnated pressboards increase with the reduction in cellulose polymer chain length.
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