| 1. |
- Liu, Daosheng, et al.
(author)
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Investigation on heating aging mechanism of cellulose paper for oil-immersed transformer main insulation
- 2019
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In: Proceedings - IEEE International Conference on Dielectric Liquids. - 2153-3733 .- 2153-3725. ; 2019-June:June
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Conference paper (peer-reviewed)abstract
- Power transformer plays a vital role in maintaining reliable and efficient electricity supply. However, in service is increasing and growing older, much and much attention has been paid on their aging condition and life assessment than ever. The aging and degradation of transformer insulation will determine the life-time of its operation. The intensities of these depend on mechanical, thermal and environmental stresses that act on the insulations. Due to the temperature rise, the lifetime of insulation material will be shortened. The accelerated thermal aging method is often adopted to do some evaluation on the oil-paper insulation materials under different temperature for the thermal lifetime model. According to existing aging test, both insulation paper and mineral oil were aged at the same temperature. In this paper, the thermal aging experiments were implemented on the transformer main insulation model made with modified and unmodified insulation paper. The accelerated thermal aging tests were finished, and the superior electric characteristics of the nano-TiO2 and cellulose composition insulation were validated.
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| 2. |
- Liu, Daosheng, et al.
(author)
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Optimization of Mass Fraction and Particle Size of TiO2 Additives in Application of HVDC Transformer Insulation
- 2019
-
In: Proceedings - IEEE International Conference on Dielectric Liquids. - 2153-3733 .- 2153-3725. ; 2019-June
-
Conference paper (peer-reviewed)abstract
- With the fast development of high voltage direct current (HVDC) transmission technology, higher electrical insulation properties are demanded in application of HVDC converter transformers. The nano adding in the cellulose insulation is a kind of effect method to enhance their electrical insulation properties. In this paper, nano-TiO2 particles with four different diameters (5 nm, 10 nm, 20 nm and 30 nm) and four different loading ratios (1 wt%, 3 wt%, 5 wt% and 7 wt%) are added during preparation of the insulation cellulose paper. To evaluate their dielectric properties, DC breakdown test, partial discharge inception voltage test, the accumulating properties of the surface charge dynamics and trap distribution characteristic are performed on the prepared nano-TiO2 modified paper samples. The experimental results show that the DC breakdown voltage and the partial discharge inception voltage of oil-immersed composition insulating paper are significantly improved by adding nano-TiO2 particles. According to the testing data, the optimum combination of 10 nm particle size and 5 wt% mass fractions were obtained, and the modification mechanism of nano-TiO2 of the nano-composition insulation were presented in the paper.
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