Local Voltage Oscillation in Interleaved Transformer Windings

Teranishi, Tsuneharu; Ikeda, Masami; Honda, Masaki; Yanari, Toshiyuki

doi:10.1109/tpas.1981.316946

Cited by 19 publications

(8 citation statements)

References 4 publications

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“…Due to Properties 1 and 2, the roots of the new polynomial P 1 (s) will be 1/(jω i ′) 2 . Likewise, from (4), a new polynomial Q 1 (s)/s can be constructed as…”

Section: Linking Roots Of a Polynomial To Its Coefficientsmentioning

confidence: 99%

“…Designers employ the well-established method of interleaving of individual turns to increase series capacitance and consequently achieve a more uniform initial impulse voltage distribution. Hence, knowledge of series capacitance is paramount for ascertaining or predetermining the winding's transient behaviour [1][2][3][4]. Although shunt capacitance is readily measurable, the same is not the case for series capacitance.…”

Section: Introductionmentioning

confidence: 99%

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Elegant procedure to estimate series capacitance of a uniform transformer winding from its measured FRA: implementable on existing FRA instruments

2020

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A simple procedure to estimate series capacitance of a uniform transformer winding from its measured frequency response analysis (FRA) and shunt capacitance is presented. Unlike previously published approaches, this method does not involve any cumbersome and time‐consuming curve‐fitting nor running optimisation/search algorithms, and neither does it require data of winding geometry. The procedure relies on a property that is observable in the impedance function of a lossless winding, viz., the ratio of the product of squares of open circuit natural frequencies to the product of squares of short circuit natural frequencies bears a special relation to impedance function coefficients. Its feasibility was initially verified by simulation, and then by experiments on small‐sized continuous‐disk and interleaved‐disc windings, followed by a large‐sized 33 kV, 3.5 MVA continuous‐disc winding, and finally on a 315 kVA 11/13.8 kV transformer. After measuring FRA, the process involves just finding roots of a polynomial, from which the initial impulse voltage distribution constant and series capacitance can directly be determined. Given these attractive features, authors believe that this method is implementable on existing FRA instruments, so that, along with routinely measured FRA, these two important constants of a winding can be displayed.

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“…Due to Properties 1 and 2, the roots of the new polynomial P 1 (s) will be 1/(jω i ′) 2 . Likewise, from (4), a new polynomial Q 1 (s)/s can be constructed as…”

Section: Linking Roots Of a Polynomial To Its Coefficientsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elegant procedure to estimate series capacitance of a uniform transformer winding from its measured FRA: implementable on existing FRA instruments

2020

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“…Among the several variants of transformer windings that have been developed and progressively refined over the decades (with modifications such as line-end shielding way back in 1930 [1], inter-shielding of winding [2,3] etc. ), the interleaved winding was a major breakthrough that came the closest to achieving the aforementioned goal, compared with what was afforded by its predecessor, viz., the continuous-disk winding [4][5][6][7]. It is well-known that it provides by far the best initial impulse voltage distribution, significant reduction in amplitude of disk-to-ground voltages and more importantly is also successful in suppressing most of the winding natural frequencies that a continuous-disk winding of similar size and rating would possess.…”

Section: Introductionmentioning

confidence: 99%

Interleaved winding and suppression of natural frequencies

Pramanik

Anees

Satish

2013

IET Electric Power Applications

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Ideally, it is desirable to design and manufacture a transformer winding that can render all its internal resonances nonexcitable. This study examines the effectiveness of an interleaved winding in achieving this goal. While investigating its effectiveness, it led to the establishment of a much desired theoretical basis that reinforces the reasons put forward in the literature to explain internal insulation failures observed in interleaved windings used in extra high voltage (EHV) transformers. Numerical calculations along with experimental verification on actual transformer windings are presented. This study reveals that most of the natural frequencies that are normally non-excitable in the line and neutral current responses of an interleaved winding have been rendered excitable in the disk-to-disk voltages, thus, providing favourable conditions for insulation overstress because of resonant overvoltages. Prevalence of such a condition is an inherent characteristic of interleaved windings.

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“…It is also known that transformers themselves exhibit high-frequency resonant behavior near 1 MHz, due to the use of windings with a large series capacitance [3].…”

Section: Introductionmentioning

confidence: 99%

A high-frequency model of an oil-immersed transformer, and its use in lightning surge analysis

et al. 2000

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A circuit model of an oil‐immersed transformer for use in surge analyses in the high‐frequency region is proposed, and its effectiveness is evaluated by comparison with measurements on a model winding. The circuit model is used for lightning surge analyses of a 500‐kV substation, and the effect of transformer modeling on the lightning surge voltage at the transformer terminals is investigated. When the new circuit model is used for transformer modeling, the peak value of the surge voltage is lower but the rate of voltage rise is higher than in conventional transformer modeling by a lumped capacitance. This difference can be explained in terms of the charging of capacitances in the transformer model. © 2000 Scripta Technica, Electr Eng Jpn, 134(1): 28–35, 2001

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Local Voltage Oscillation in Interleaved Transformer Windings

Cited by 19 publications

References 4 publications

Elegant procedure to estimate series capacitance of a uniform transformer winding from its measured FRA: implementable on existing FRA instruments

Elegant procedure to estimate series capacitance of a uniform transformer winding from its measured FRA: implementable on existing FRA instruments

Interleaved winding and suppression of natural frequencies

A high-frequency model of an oil-immersed transformer, and its use in lightning surge analysis

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