The Development of Electrical Tree Discharge in Epoxy Resin Impregnated Paper Insulation

Wang, Yongqiang; Feng, Chao; Luo, Yi

doi:10.1109/access.2020.2986482

Cited by 11 publications

(5 citation statements)

References 25 publications

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“…The formation of free radicals in polymer would lead to a free-radical chain reaction and subsequently the generation of low-molecular products (e.g., hydroxyl, epoxy, etc.) [ 30 , 31 ]. The local area with the low-molecular products is called low-density regions [ 32 ].…”

Section: Discussionmentioning

confidence: 99%

Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin

et al. 2020

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The application of wide band-gap power electronic devices brings more challenges to insulating packaging technology. Knowing the influence of applied voltage parameters on insulation performance is helpful to evaluate the insulation condition of electric power equipment. In this paper, the effect of repetitive square wave voltage duty cycle on the growth characteristics of electrical trees in epoxy resin was studied. The experimental results show that the square wave voltage duty cycle has a significant influence on treeing features. The electrical tree proportion initiation has shown a decreasing trend, and the shape of the electrical tree changes from pine-like to branch-like by increasing the duty cycles. The length and damaged area of electrical tree increased with the increase in the duty cycle up to 10% and then decrease by increasing the duty cycle higher than 30%. It indicates that a low duty cycle will enhance the electron injection and accumulate space charges and thus accelerate electrical tree development. Under short duty cycles, the electric field due to the shielding effect near the needle tip suppresses the electrical tree growth, which results in treeing growth stagnation. The obtained results are helpful to keep these parameters in mind during the design of epoxy-based insulation such high-voltage rotating machines and power electronic device packaging.

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Section: Discussionmentioning

confidence: 99%

Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin

et al. 2020

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“…The results showed that the development process of the electrical tree discharge went through the initial, growth, stagnation, and rapid development stages, in which the suppression of space charge in the stagnation stage reduces the rate of forward extension of the main path of the electrical tree. 23 Zhikang Yuan et al investigated the growth law of electrical trees in glass fiber/epoxy composites. It was found that when the breakdown strength of the interface was the same as that of the air gap, the electrical tree at the interface showed a "linear growth".…”

Section: ■ Introductionmentioning

confidence: 99%

“…Wang et al investigated the development process of the electrical tree discharge between the layers of epoxy resin-impregnated paper. The results showed that the development process of the electrical tree discharge went through the initial, growth, stagnation, and rapid development stages, in which the suppression of space charge in the stagnation stage reduces the rate of forward extension of the main path of the electrical tree . Zhikang Yuan et al investigated the growth law of electrical trees in glass fiber/epoxy composites.…”

Section: Introductionmentioning

confidence: 99%

Influence of Epoxy Resin Interlayer Interfaces on Electrical Tree Growth and Breakdown Characteristics

Wang,

Li,

Zhou

et al. 2024

Langmuir

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The solid−solid insulation interface structure is a typical interface in extra-high-voltage power equipment, in which the multilayer epoxy resin material is a key component in the insulation structure of the power equipment, and the study of its interface characteristics is the most important. In this paper, epoxy−epoxy cross-linking interface specimens were prepared through experiments, and the degree of cross-linking between the interfaces was analyzed by changing the ratio of the curing agent and adding hydroxyl-terminated liquid nitrile rubber (HTBN) particles; it can be concluded that there exists a weak cross-linking reaction between the interfaces. The electrical tree measurement and alternating current (AC) breakdown test platform were set up, and three different cases of no interface, the electric field direction parallel to the interface, and the electric field direction perpendicular to the interface were tested, through which it was concluded that the existence of the interface inhibited the development of the electrical tree. For the three different cases of AC breakdown tested, it was concluded that the presence of an interface enhances the AC breakdown strength when the electric field direction is parallel to the interface and decreases the AC breakdown strength when the electric field direction is perpendicular to the interface through the interface, affecting the charge transport.

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“…However, because the above study used an interface perpendicular to the electric field direction, the role of the interface in the development of electrical trees is difficult to observe. Considering that the paper is an uneven structure, a model based on E51 epoxy resin (ER)‐impregnated kraft paper was produced to simulate the edge structure, whose results showed that the interface had an induced effect on electrical tree development [14]. However, a real dry‐type bushing core mainly uses special crepe paper and ER material with ultra‐long available time at temperatures below 60°C.…”

Section: Introductionmentioning

confidence: 99%

Degradation characteristics of insulation near aluminium foil edges inside dry‐type bushing cores under electrothermal compound stress

et al. 2022

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Insulation breakdown of dry‐type valve‐side bushing cores under electrothermal compound stress has become a key factor limiting the safe and stable operation of the converter transformer. Based on slices of the real bushing core, it is observed for the first time that fold, peeling off, and fracture defects exist near the aluminium (Al) foil edge, accompanied by many metal spikes with a curvature radius <4 μm. Coupled with a capacitor screen thickness of ∼2 mm, an electrical tree model is designed to simulate insulation defects near aluminium foil edges inside dry‐type bushing cores, whose insulation degradation characteristics under electrothermal compound stress are investigated accordingly. The results show that high temperature significantly increases the dielectric loss heat energy density and Joule heat energy density, accelerating the insulation degradation near Al foil edges. The parallel crepe paper interface significantly accelerates the growth of electrical trees under AC‐superimposed positive DC voltage, while this effect is not significant under AC voltage. As the crepe paper consists of wooden fibres of 10 μm diameter, the electrical trees tend to grow along interfaces between fibres and epoxy resin to form “feathery” electrical trees in epoxy resin‐impregnated paper samples.

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The Development of Electrical Tree Discharge in Epoxy Resin Impregnated Paper Insulation

Cited by 11 publications

References 25 publications

Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin

Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin

Influence of Epoxy Resin Interlayer Interfaces on Electrical Tree Growth and Breakdown Characteristics

Degradation characteristics of insulation near aluminium foil edges inside dry‐type bushing cores under electrothermal compound stress

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