Journal ArticleDOI
Understanding the dielectric properties of pressboard material thermally aged in Dibenzyl Disulphide (DBDS) included transformer oil
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TLDR
In this paper, the surface discharge inception voltage (SDIV) of unaged and copper sulphide diffused OIP material was studied by adopting Ultra High Frequency (UHF) technique.Abstract:
Surface Discharge Inception Voltage (SDIV) of unaged and copper sulphide diffused Oil Impregnated Pressboard (OIP) material was studied by adopting Ultra High Frequency (UHF) technique. Copper sulphide diffusion into OIP material was carried out by thermal aging of pressboard material in Dibenzyl Disulphide (DBDS) added transformer oil. The SDIV reduces with increase of thermal aging temperature. The current pulse injected in positive and negative half cycle during the surface discharge of the AC shows the rise time of 0.8ns and 1ns respectively. The FFT analysis of UHF signal measured during surface discharge process has shown frequency content in the range 0.7–1.2 GHz with its dominant frequency at 0.9 GHz. The life of the charge presented on the pressboard increases with thermal aged specimen. Energy dispersive spectroscopy (EDS) analysis of OIP material indicates presence of copper and sulphur content. Frequency Domain Dielectric Spectroscopy (FDDS) studies indicate the permittivity(er), dissipation factor (tan(δ)), conductivity (σdc) increases and relaxation time (τ), coefficient (α) decrease with OIP material (in air / Nitrogen) aged at higher temperature in DBDS added transformer oil. Cole-Cole double relaxation model was used to understand the dielectric parameters of copper sulphide diffused OIP material. The DC conductivity of pressboard material aged in DBDS included transformer oil follows Arrhenius law and the activation energy decreases with increase in temperature of thermal aging.read more
Citations
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Journal ArticleDOI
Temperature Compensation of Frequency Domain Spectroscopy Measurement for Condition Assessment of Oil-Paper Insulation
TL;DR: In this article , a novel method for predicting frequency-domain spectroscopy (FDS) characteristics of oil-paper insulation at a temperature, which is different from the measurement temperature, through estimating activation energy.
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.
Book ChapterDOI
Assessment of Dielectric Paper Degradation through Mechanical Characterisation
Cristina Fernandez-Diego,Inmaculada Fernández,Felix Ortiz,IsidroCarrascal,Carlos J. Renedo,Fernando Delgado +5 more
TL;DR: The authors of as mentioned in this paper were grateful for the funding received to carry out this work from the State Scientific and Technical Research and Innovation Plan under the DPI2013-43897-P grant agreement, financed by the Government of Spain.
Journal ArticleDOI
Investigation on electrical, thermal and mechanical properties of thermally aged pressboard impregnated with mixed mineral oil and synthetic ester fluid
Amizhtan Somasundaram Karthikeyan,Gorla Durga Pawan Mahidhar,Ramanujam Sarathi,Nathaniel Taylor,Hans Edin +4 more
TL;DR: In this paper, the electrical, thermal and mechanical performances of cellulose pressboard material impregnated in mineral oil, synthetic ester fluid and mixed oil are compared by means of tensile strength measurement and thermo-gravimetric analysis.
References
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Bringing an insulation to failure: the role of space charge
TL;DR: The goal is to show how much space charge can contribute directly or indirectly, through local electric field magnification or alteration, to increase ageing rate or even trigger more energetic, thus faster, degradation processes in insulation design and electrical apparatus long-term performance/reliability.
Journal ArticleDOI
Deriving an equivalent circuit of transformers insulation for understanding the dielectric response measurements
TL;DR: In this article, a circuit model, which describes the dielectric behavior of the transformer's main insulation system, has been parameterized in order to identify the values of the parameters of the model and the correlation has been developed between the physical condition of the insulation and the equivalent model parameters that enable a clear and transparent interpretation of the test results.
Journal ArticleDOI
UHF and current pulse measurements of partial discharge activity in mineral oil
G.P. Cleary,Martin D. Judd +1 more
TL;DR: In this article, the relationship between radiated ultra-high frequency (UHF) signals and electric charge in a partial discharge (PD) current pulse for PD sources in oil insulation was explored.
Journal ArticleDOI
A pulsed GTEM system for UHF sensor calibration
Martin D. Judd,O. Farish +1 more
TL;DR: A system for measuring the sensitivity of electric field sensors at UHF using a novel gigahertz transverse electromagnetic (GTEM) cell is described to enable calibration of UHF couplers that are used to detect insulation defects in gas insulated substations.
Proceedings ArticleDOI
Effective methods of assessment of insulation system conditions in power transformers: a view based on practical experience
V. Sokolov,Z. Berler,V. Rashkes +2 more
TL;DR: In this article, a functional failure model of power transformer insulation and possible effective methods of the insulation condition assessment are discussed based on practical experience, and a substantial drop in the dielectric safety margin under the impact of moisture, oil by-products, contaminating particles, paper insulation aging and partial discharge activity.
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