Journal ArticleDOI
Dielectric spectroscopic measurements on transformer oil-paper insulation under controlled laboratory conditions
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TLDR
A detailed study of the effect of ageing, temperature and moisture on frequency and time domain spectroscopic measurements carried out on oil-impregnated pressboard samples as well as on a distribution transformer under controlled laboratory conditions is reported in this article.Abstract:
For reliable operation of power transformers, the condition of the insulation system is essential. This paper reports on a detailed study of the effect of ageing, temperature and moisture on frequency and time domain spectroscopic measurements carried out on oil-impregnated pressboard samples as well as on a distribution transformer under controlled laboratory conditions. Because field measurements are generally performed after de-energizing the transformer, extreme care is required in interpreting the results due to inherent temperature instabilities. To avoid large thermal variations that may affect the results, a customized adiabatic room was built around the transformer for measurements above the ambient. Capacitance ratio and direct current conductivity deduced from the spectroscopic measurements, helped to interpret the data. Because, low frequency measurements techniques are time consuming, alternative to a transfer of time domain data into frequency domain data was investigated.read more
Citations
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Journal ArticleDOI
Condition Monitoring of Power Transformers - Bibliography Survey
TL;DR: In this article, the authors proposed a preventive maintenance technique for power transformers, such as DGA, thermal monitoring, partial discharge measurement, capacitance and tan delta measurements, frequency response analysis, etc., to identify problems at an early stage before a catastrophic failure occurs.
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
A critical review of plant-based insulating fluids for transformer: 30-year development
TL;DR: In this article, the research status of plant-based insulating fluids for transformer, including both challenges and outlook circa 2020, is reviewed, with a focus on the fire-safety and environmental requirements.
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Quantitative analysis ageing status of natural ester-paper insulation and mineral oil-paper insulation by polarization/depolarization current
TL;DR: In this paper, a new method for assessing the ageing condition of the oil-paper insulation in terms of the depolarization charge quantity was proposed, which can also be used to assess the condition of new insulation system using natural ester in transformers accurately.
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.
References
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Book
Dielectric relaxation in solids
TL;DR: In this paper, a broad-brush view of dielectric relaxation in solids is presented, making use of the existence of a universality of Dielectric response regardless of a wide diversity of materials and structures with dipolar as well as charge-carrier polarization.
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Review of modern diagnostic techniques for assessing insulation condition in aged transformers
TL;DR: A description of commonly used chemical diagnostics techniques along with their interpretation schemes for transformer insulation condition assessment is presented.
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Dielectric spectroscopy in time and frequency domain for HV power equipment. I. Theoretical considerations
TL;DR: In this article, the theoretical background of dielectric spectroscopy in the time and frequency domains is introduced and an overview about the specific measuring methods based on this background is provided, and specific methods treated are used for diagnosing electric insulation materials used in power engineering.
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Applications of dielectric spectroscopy in time and frequency domain for HV power equipment
TL;DR: In this article, the authors proposed an off-line, on-site insulation condition assessment of HV electric power equipment and its predictive maintenance using dielectric spectroscopy in the time or frequency domain.
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Moisture equilibrium in transformer paper-oil systems
TL;DR: The authors provides an overview of the classic moisture equilibrium curves and their history and provides useful information on the relationships among them and their validity, as well as their relationship among different types of equilibrium curves.