A field study of aging in paper-oil insulation systems

Lelekakis, N.; Guo, Wei; Martín, D.; Wijaya, J.; Susa, D.

doi:10.1109/mei.2012.6130527

Cited by 78 publications

(46 citation statements)

References 7 publications

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“…Insulation attacked by ageing will work ineffectively and is likely to be failed. An effective assessment method is urgently needed to extend transformer lifetime and prevent the failure [3][4].…”

Section: Introduction a Power Transformermentioning

confidence: 99%

Study on Correlation Among Oil Dielectric Characteristics, Dissolved Gases, and Operating Life of 150 kV Power Transformer

Diwyacitta¹,

Prasojo²,

Suwarno³

2017

ijeei

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Power transformer undergo aging overtime that degrades its insulation system. Oil-immersed paper insulation degradation in transformer can be assessed through the change in oil characteristics and the dissolved gases. Data related to these parameters are abundant, but study on correlation among these parameters and the operating time of power transformer is still limited. This paper presents statistical insights into aging of transformer insulation system through oil characteristics, dissolved gases and the operating time of transformer. As much as 219 in service 150 kV transformers population testing data were included in this study. The data was analyzed using linear regression correlation analysis to Figureure out the dependency of each parameters. Statistical correlation between each properties of oil insulation, dissolved gases and operating time were carried out. There are some oil properties that have correlation with operating time, which are color scale, IFT and acidity. Moreover, color scale, IFT and acidity shows dependency among them. IFT tends to gradually decrease while acidity increases as operating time trend rises. On the other hand, operating time are also highly correlated with CO and CO2, which are commonly known as the main product of paper insulation degradation in transformers. Correlation among prior correlated parameters found that CO is strongly correlated with color and IFT. Subsequently, a high correlation coefficient of parameter to operating time could be interpreted that the ageing process happens during the life of a transformer changes certain parameters which these changes should be noticed for better decision making whether the transformer still feasible to be used in the system with certain maintenance or should be replaced.

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Section: Introduction a Power Transformermentioning

confidence: 99%

Study on Correlation Among Oil Dielectric Characteristics, Dissolved Gases, and Operating Life of 150 kV Power Transformer

Diwyacitta¹,

Prasojo²,

Suwarno³

2017

ijeei

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“…Additionally, it could be possible to estimate the remaining lifetime of transformers wich are identical in their design if loading conditions and maintenance are available [10]. Different authors have published end-of-life studies of scrapped transformers [11][12][13][14][15][16]. All these works are based on the measuring DP which constitutes one of the most important parameters of the insulation conditions.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the temperature distribution into a transformer through tensile index

Fernández¹

2024

RE&PQJ

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Abstract. Power transformers are electrical machines which are one of the most critical components in power distribution systems worldwide. Their failure generally is due to the degradation of its insulating system (insulating oil and paper insulation). This deterioration is produced by electrical, mechanical, chemical and thermal stresses which power transformers suffer during their operational lifetime. When dielectric paper has aged severely it loses its tensile strength and its capability to withstand electrical faults decreases considerably. This paper describes an end of life study carried out on a distribution transformer. This analysis has used the tensile index of the dielectric paper to estimate the temperature distribution in the windings of the electric machine. The tensile index is a mechanical parameter associated with the state of the paper insulation that protects the conductors of the windings. By knowing the value of this magnitude for a new and for an aged paper, and the period of operation of a transformer, the temperature distribution along the height of the windings can be estimated. These results and the load rate that a transformer has endured during its life can provide useful information for future designs or for similar transformers still in operation.

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“…Oxidation, which is the primary ageing mechanism for the liquid insulation, typically mineral oil, will produce moisture particularly when hydroxyl radicals react with hydrocarbon molecules in the branching stage of oil oxidation [4][5][6]. As for the solid insulation, typically Kraft paper, initial oxidation and the subsequently dominant acid-catalysed hydrolysis will also produce moisture through the cleaving of inter-unit linkages in cellulose or hemicellulose [2], [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…It is well documented that moisture present in insulating oil distorts electric field distribution, increases the electrical conductivity of the oil, and ultimately decreases the breakdown voltage of the oil, indicating lower effectiveness of the oil as a dielectric [11][12][13][14][15][16][17][18][19][20]. As for the solid insulation, moisture which is both a product from and a trigger to acid catalysed hydrolysis thus further accelerates paper decomposition [2], [7][8][9], [21], undermining not just its dielectric strength [3], [22], but also more significantly its mechanical strength in terms of tensile, bursting and folding strengths [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%