Moisture in cellulose insulation of power transformers - statistics

Gielniak, J.; Graczkowski, A.; Morańda, H.; Przybyłek, Piotr; Walczak, K.; Nadolny, Zbigniew; Mościcka-Grzesiak, H.; Feser, K.; Gubanski, Stanislaw

doi:10.1109/tdei.2013.6518968

Cited by 48 publications

(34 citation statements)

References 7 publications

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“…The ageing may result in deterioration of many properties of the insulating system, such as resistance drop, increase of dielectric losses tan(δ), moisture increase [6,13,14,22,26]. The mentioned above results were often a reason of transformer breakdown or destruction in the past [9].…”

Section: Introductionmentioning

confidence: 99%

Liquid kind, temperature, moisture, and ageing as an operating parameters conditioning reliability of transformer cooling system

Dombek¹,

Nadolny²

2016

EiN

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Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl 413 Grzegorz Dombek Zbigniew NADolNyLiquid kind, temperature, moisture, and ageing as an operating parameters conditioning reLiabiLity of transformer cooLing system rodzaj cieczy, temperatura, zawiLgocenie oraz zestarzenie jako parametry ekspLoatacyjne warunkujące niezawodność układu chłodzenia transformatora*

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Section: Introductionmentioning

confidence: 99%

Liquid kind, temperature, moisture, and ageing as an operating parameters conditioning reliability of transformer cooling system

Dombek¹,

Nadolny²

2016

EiN

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“…cellulose, resin) and polymers (e.g. aramid paper, polyvinyl chloride) [10]. Pressboard is a type of pressed cellulose cardboard produced by wet felting of vegetable fiber and flattening.…”

Section: Characteristic Of Materials Applied In the Studymentioning

confidence: 99%

“…For cellulose preparation, there is a need to apply two processes: acidic and alkaline, where it is less damaging for chemical molecules. Pressboard cellulose can be simply formed, trimmed or crushed so it is a commonly used material for insulating electrical conductors and transformers of high power [10]. It is a composite material like paper with the variation of sheet thickness ranged from 0.1 mm to plates of 50 mm.…”

Section: Characteristic Of Materials Applied In the Studymentioning

confidence: 99%

Comparative analysis of cellulose pressboard and aramid paper used in air insulation systems of high-voltage devices

Turba

Frącz

2017

E3S Web Conf.

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Abstract. The paper presents results of a comparative analysis of parameters of two kinds of solid dielectrics used in air insulation systems to prevent occurring partial discharges. The research works regarded materials made of: cellulose pressboard and aramid paper. All measurements were performed under laboratory conditions by changing the value of partial discharges generation voltage until breakdown occurred in the inhomogeneous environment that was simulated using needle-plate (made of copper) electrode system. The main contribution which resulted from studies is a statement that potential use of aramid paper as a dielectric can extend the life of a high voltage electric device as compared to standard cellulose pressboard usage due to higher electric resistances to breakdown or detection of corona voltage. Results shown that the aramid paper has greater electric resistance to breakdown in comparison to cellulose with no difference between both on detecting corona of partial discharge.

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“…This problem refers first of all to devices insulated with cellulose materials impregnated with electro-insulating liquids [4,5]. Examples of such devices are power transformers and instrument transformers.…”

Section: Introductionmentioning

confidence: 99%

“…This problem has been discussed in different scientific publications many times [2,4,15], mainly in terms of oil-paper insulation moisture of power transformers. Authors of these articles notice that water is not only a decomposition product of cellulose insulation but it also contributes to this decomposition.…”

Section: Introductionmentioning

confidence: 99%

Application of capacitive sensor for measuring water content in electro-insulating liquids

Przybyłek

Siodła

2016

EiN

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Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThe presence of water in the electro-insulating system of power devices is a serious operational problem. This problem refers first of all to devices insulated with cellulose materials impregnated with electro-insulating liquids [4,5]. Examples of such devices are power transformers and instrument transformers. This problem also refers to transformer bushing insulators.With passing years of operation of a given device, its insulation moisture rises. This problem has been discussed in different scientific publications many times [2,4,15], mainly in terms of oil-paper insulation moisture of power transformers. Authors of these articles notice that water is not only a decomposition product of cellulose insulation but it also contributes to this decomposition. As a result of water presence in the insulating system and exposure to high temperature, the process of cellulose depolimerization takes place, which results in a decrease of its mechanical strength [1,12,17]. Other disadvantageous consequences of water presence in the insulating system are: electric strength drop of the insulation, lowering the inception voltage of partial discharges [19], and the threat of the bubble effect appearance [8,11], which increases with more moistened cellulose insulation. High insulation moisture forces restrictions of the device load. One of positive aspects of water presence in solid insulation is the increase of its thermal conductivity, which to a certain extent improves cooling of the transformer windings [7]. However, negative results of water presence are predominant and there is a trend to reduce the insulation moisture of power devices as much as possible.Due to long-lasting operation of power devices, the problem of moisture is serious and concerns not only the Polish electric power system but also the systems of most countries. The problem of insulation moisture has been known to the international community for a few decades and it is still a current issue, which is confirmed by the newest publication of the worldwide range: they concern, among others, moisture measurement methods of transformer insulation [6,13,20], also problems connected with forms of water presence [3,13,21] and its migration in the cellulose−electro-insulating liquid system [2,15]. Nowadays, the activities of the international CIGRE Working Group WG D1.52 Moisture measurement in insulating fluids and transformer insulation are in progress. Their purpose is, among others, to improve reliability of water content measurement methods in electro-insulating liquids. Capacitive probe for measuring water content in electro-insulating liquidThe most frequently used method of measuring water content in electro-insulating liquids is titration method which makes use of the Karl Fischer reaction (KFT -Karl Fischer Titration). It is a standardized method [10] which is characterized by high accuracy of water con...

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Moisture in cellulose insulation of power transformers - statistics

Cited by 48 publications

References 7 publications

Liquid kind, temperature, moisture, and ageing as an operating parameters conditioning reliability of transformer cooling system

Liquid kind, temperature, moisture, and ageing as an operating parameters conditioning reliability of transformer cooling system

Comparative analysis of cellulose pressboard and aramid paper used in air insulation systems of high-voltage devices

Application of capacitive sensor for measuring water content in electro-insulating liquids

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