Generalised frequency response applied to dielectrics

Belmont, M.R.; May, E.J.P.; Horwood, M.K.

doi:10.1049/cp:19960983

Cited by 8 publications

(14 citation statements)

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“…As a result, the FDS method requires larger measuring times to resolve the diagnostic status, whereas the SFRA method can be performed within few minutes. In this context, there is an increasing interest in extending the SFRA method in the process of determining the diagnostic status of winding insulation of a transformer at higher frequencies . In case of any deviation, a detailed FDS‐based analysis may be recommended for further clarification.…”

Section: Introductionmentioning

confidence: 99%

“…Literatures indicate that moisture and pertinent material degradation affects the integrity of winding insulation and, in some cases, causes changes in the interturn and disc‐to‐disc arrangement . Naturally, these deviations could be better observed at both lower and higher frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…In this context, there is an increasing interest in extending the SFRA method in the process of determining the diagnostic status of winding insulation of a transformer at higher frequencies. [7][8][9][10][11][12][13][14][15][16] In case of any deviation, a detailed FDS-based analysis may be recommended for further clarification. Following this, there are several attempts made to expand the possibilities of SFRA method to be used for measuring the diagnostic status of the transformer.…”

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confidence: 99%

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Theoretical considerations while applying sweep frequency response analysis method in determining the interwinding capacitance of power transformers at higher frequencies

Arumugam

2019

Engineering Reports

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This paper systematically investigates on theoretical and practical aspects of frequency response analysis method in evaluating the dielectric integrity of transformers. Current practices focus on interwinding capacitances as they contain sensitive diagnostic information of transformer windings, magnetic core, and insulation. However, these procedures are inadequate as they are experience based, frequency limited, and overlook the electromagnetic influence of winding core during interwinding capacitance measurements. Corresponding interpretations are subjective and require an expert's decision. Clearly, a method based on trials and involving subjective analysis procedures may render inaccurate and unreliable results. On contrary, if the influence of winding core is minimized, then the high‐frequency cutoff limit can be widened, and the interwinding capacitances can be accurately determined. Presumably, the influence of winding core can be minimized via careful selection of terminal connection, system function pair. For this purpose, resistance‐capacitance and ladder network models describing the impulse behavior of winding‐insulation‐core of transformers are simulated. A suitable terminal connection, system function pair that minimizes the influence of winding‐core is identified. Subsequently, the sensitivity of the proposed method and the accuracy of interwinding capacitance measured are ascertained through comparative analysis and experimentally verified on model coils and transformers. Pertinent interpretations are objective and reveal the sensitive diagnostic information of transformers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Theoretical considerations while applying sweep frequency response analysis method in determining the interwinding capacitance of power transformers at higher frequencies

Arumugam

2019

Engineering Reports

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“…

in geosynchronous orbit (GEO) or low earth orbit (LEO) They can be used for both insulation purposes and for interacts with the local space environment resulting in the charge storage, in addition to other purposes like heat differential charging of the spacecraft to electrical conduction (as in liquids) and mechanical support (as in potentials of many hundreds to few thousand volts.

…”

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confidence: 99%

“…electrical insulation for multi-stress and high repetition rate (high frequency operation) compact and/or high Surface flashover across solid insulators in vacuum voltage/power electrical systems [4].…”

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Surface Flashover Characteristics of Nano Particle Cast EPOXY Resin

Serkan

Kirkici

Koppisetty

2005

2005 IEEE Pulsed Power Conference

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electrical insulation for multi-stress and high repetition rate (high frequency operation) compact and/or high Surface flashover across solid insulators in vacuum voltage/power electrical systems [4].has found applications in the area of space power systems. One scenario where surface flashover in vacuum can be a Insulating materials play a significant role in the problem in space power systems is a spacecraft operating design and performance of high voltage power systems.in geosynchronous orbit (GEO) or low earth orbit (LEO) They can be used for both insulation purposes and for interacts with the local space environment resulting in the charge storage, in addition to other purposes like heat differential charging of the spacecraft to electrical conduction (as in liquids) and mechanical support (as in potentials of many hundreds to few thousand volts. When solids). Despite the basic understanding of electrical this charging reaches a critical value, surface flashover on breakdown of materials, electrical surface flashover the solid dielectric insulator may occur, resulting in loss phenomena, physical mechanisms responsible for the of high voltage isolation and damage to the space power initiation of such unwanted electrical activities within an systems on board. Similarly, surface flashover can also insulation system composed of such advanced materials occur across insulators in the utility power system in must be investigated before they can be commercially atmospheric pressures as well. In general, random available. The findings of such studies are essential for emission of a small number of electrons at the cathode the development of nano-electric and other advanced results in positive charging of the dielectric surface at the materials and the techniques to predict the reliability of triple junction, thus initiating surface flashover across the the advanced electrical systems which utilize these dielectric. materials.In this paper, we present experimental results of It is widely accepted that the surface flashover surface flashover characteristics of epoxy resin and epoxy phenomenon is due to field emission of electrons at the resin cast with powdered A1203. The samples used in the cathode 'triple-junction' (electrode/insulator/vacuum experiments were produced by using either epoxy resin of interface) when the applied field exceeds a certain known properties or by mixing known quantities of A1203 threshold value [5]. Random emission of a small number with epoxy. The electrode material placed over the of electrons at the cathode results in positive charging of dielectric samples was copper. The flashover studies the dielectric surface at the triple junction. Consequently, were conducted using DC and AC signals separately, and this creates an electron avalanche across the surface surface flashover voltage characteristics and the towards the anode, which is followed by an electrical breakdown voltage wave forms of samples were breakdown and plasma generation on the surface of the determined.dielectric. There are...

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Experimental validation of using frequency response analysis method in measuring interwinding capacitance of power transformers

Arumugam

2019

Engineering Reports

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The interwinding capacitance of transformers describes the diagnostic status of winding‐insulation and its geometry. Naturally, there is a constant drive in improvising the existing methods and to attain accurate information while measuring interwinding capacitance of a transformer. In this regard, frequency response analysis method is increasingly used in measuring the interwinding capacitance of transformers. The primary reason for applying this method is to establish a faster evaluation method for diagnosing the status of the winding‐insulation through the interwinding capacitances. However, the pertinent measurement procedures are inadequate as they tend to resolve the interwinding capacitances along with the electromagnetic influence of winding‐core assembly, thus making it difficult to diagnose the status of the winding‐insulation. This intricacy could be overcome by making an optimal choice of terminal configuration, that is, a combination of terminal connection, system function, mode of excitation that would minimize the electromagnetic influence of winding‐core in their respective spectra. In this context, the theoretical aspects of making an optimal choice of terminal configuration have already been investigated, and the suitability of the same on actual in‐service power and distribution transformers needs to be validated. This forms the primary focus of this article. A rigorous and systematic experimental study is adapted to verify the existing findings and validate the same on larger power and distribution transformers. After verification, the proposed method may be identified as sensitive in determining the interwinding capacitance of transformers and further recommended during frequency response measurements.

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Generalised frequency response applied to dielectrics

Cited by 8 publications

References 0 publications

Theoretical considerations while applying sweep frequency response analysis method in determining the interwinding capacitance of power transformers at higher frequencies

Theoretical considerations while applying sweep frequency response analysis method in determining the interwinding capacitance of power transformers at higher frequencies

Surface Flashover Characteristics of Nano Particle Cast EPOXY Resin

Experimental validation of using frequency response analysis method in measuring interwinding capacitance of power transformers

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