Damage assessment of transformer Kraft paper insulation aged in mineral and vegetable oils

Fernández-Diego, Cristina; Ortiz, Alfredo; Carrascal, I.; Fernández, Inmaculada; Estébanez, Carlos Javier Renedo; Delgado, F.; Diego, Soraya

doi:10.1007/s10570-019-02246-x

Cited by 14 publications

(8 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4c). The behavior is consistent with the literature [8] and indicates for DP < 300 (aging time > 400 h) the break strain is < 1 % and at this point the paper would be considered to be at the end of life [4]. Thus it is possible here to prepare samples for flow testing covering the full range of available mechanical properties.…”

Section: Effect Of Aging On Mechanical Propertiessupporting

confidence: 85%

Effects of aging on the mechanical and dielectric properties of transformer grade Kraft paper

Hosier

Lewin

Pilgrim

et al. 2020

2020 IEEE Electrical Insulation Conference (EIC)

View full text Add to dashboard Cite

In order to understand the aging process of paper used in high voltage transformers, transformer grade Kraft paper samples were aged in a fan oven in order to access the full range of DP values from 1100 (new) to ~200 (end of life). The absence of significant oxidation was verified by infrared spectroscopy and the mechanical and dielectric properties were assessed as a function of DP. Whilst the dielectric properties (in the absence of water) were unaffected by aging, the tensile strength was reduced. This confirms studies in the literature which show that most transformer breakdowns occur through mechanical failure of the paper and crucially, provides a mechanism of providing paper samples of known DP for subsequent exposure to oil flow.

show abstract

Section: Effect Of Aging On Mechanical Propertiessupporting

confidence: 85%

Effects of aging on the mechanical and dielectric properties of transformer grade Kraft paper

Hosier

Lewin

Pilgrim

et al. 2020

2020 IEEE Electrical Insulation Conference (EIC)

View full text Add to dashboard Cite

show abstract

“…The limit of the temperature rise at the top of the oil in power transformers was set at 60 • C [25]. Therefore, an increase above this rise would elevate the aging rate as it happens with pure dielectric oils [14,15].…”

Section: Methodology Of Thermal Agingmentioning

confidence: 99%

“…For this reason, some authors have focused their works on these characteristics [10][11][12][13]. Their results conclude that magnetic fluids reduce temperatures at transformer winding and top oil, which would diminish the aging rate as it happens with pure dielectric liquids [14,15].…”

Section: Introductionmentioning

confidence: 99%

Effect of TiO2 and ZnO Nanoparticles on the Performance of Dielectric Nanofluids Based on Vegetable Esters During Their Aging

et al. 2020

View full text Add to dashboard Cite

Over the last few decades the insulating performance of transformer oils has been broadly studied under the point of view of nanotechnology, which tries to improve the insulating and heat dissipation performance of transformer oils by suspending nanoparticles. Many authors have analyzed the thermal and dielectric behavior of vegetable oil based-nanofluids, however, very few works have studied the evolution of these liquids during thermal aging and their stability. In this paper has been evaluated the performance of aged vegetable oil based-nanofluids, which have been subjected to accelerated thermal aging at 150 °C. Nanoparticles of TiO2 and ZnO have been dispersed in a commercial natural ester. Breakdown voltage, resistivity, dissipation factor and acidity of nanofluid samples have been measured according to standard methods, as well as stability. Moreover, it has been analyzed the degradation of Kraft paper through the degree of polymerization (DP). The results have showed that although nanoparticles improve breakdown voltage, they increase the ageing of insulation liquids and dielectric paper.

show abstract

“…The papers were cut into 7 cm square pieces for dielectric analysis and into strips of 26 cm x 1.5 cm for tensile test. Due to paper anisotropy [9]- [11], the strips were cut with two different fiber direction angles (longitudinal and transverse) to measure mechanical properties (tensile strength, strain, energy per unit volumen...).…”

Section: A Samplesmentioning

confidence: 99%

Dielectric and mechanical assessment of cellulosic insulation during transformer manufacturing

Sanz

Sancibrian

Fernández

et al. 2021

2021 IEEE Electrical Insulation Conference (EIC)

View full text Add to dashboard Cite

Due to the impact of cellulose of paper insulation on transformer life, it is imperatire to remove moisture from the oil and the solid insulation. Several techniques have been implemented during manufacturing of power transformers to reduce water content in transformers. These drying processes can involve different costs and time, and they can damage the insulation paper. In this work, a drying process has been implemented in the laboratory trying to simulate the most aggressive conditions that can be suffered by the paper in transformer manufacturing in a real industry. Then the effect of the drying process on paper was evaluated using the analysis of mechanical and dielectric properties and the degree of polymerization. Different commercial papers were studied to quantify the possible degradation induced by the drying process. The results of the mechanical strength study showed a reduction on the degree of polymerization from 1100 to 850 after 4 days of drying. The dielectric analysis of the samples showed different behavior in one of the solids evaluated and it was also found a decreased hygroscopic capacity of degraded samples in comparison with new samples.

show abstract

Damage assessment of transformer Kraft paper insulation aged in mineral and vegetable oils

Cited by 14 publications

References 44 publications

Effects of aging on the mechanical and dielectric properties of transformer grade Kraft paper

Effects of aging on the mechanical and dielectric properties of transformer grade Kraft paper

Effect of TiO2 and ZnO Nanoparticles on the Performance of Dielectric Nanofluids Based on Vegetable Esters During Their Aging

Dielectric and mechanical assessment of cellulosic insulation during transformer manufacturing

Contact Info

Product

Resources

About