Study on the influence mechanism of ambient humidity on the temperature rise of decay‐like composite insulators

Zhong, Zheng; Yuan, Chen; Liu, Yunpeng; Hou, Sizu; Geng, Jianghai

doi:10.1049/hve2.12170

Cited by 11 publications

(8 citation statements)

References 15 publications

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“…The abnormal heating phenomenon in aged composite insulators is mainly attributed to dielectric losses. These losses are induced by the polarization effect of the dielectric material when exposed to the power frequency alternating electric field [31]. The equivalent electrical circuit model for the core rod material is illustrated in Figure 15.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Study on the Mechanism Effect of Bending Loads on the Decay-like Degradation of Composite Insulator GFRP Core Rod

Yi,

Ding,

Liu

et al. 2024

Energies

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This paper investigates the deterioration of, and the abnormal temperature rise in, the GFRP core rod material of compact V-string composite insulators subjected to prolonged alternating flexural loading under wind-induced stresses. The axial stress on the GFRP (Glass Fiber Reinforced Plastic) core rod, resulting from transverse wind loads, is a focal point of examination. By establishing a stress model and damage model, the paper simulates and computes the evolution of damage in the outer arc material of composite insulator core rods subjected to alternating flexural loads. Additionally, a multi-factor coupled aging platform is set up, integrating humidity, heat, and mechanical stress, to simulate the crazing deterioration process of composite insulators under alternating flexural loads. Experimental results reveal that during 400,000 alternating load cycles, the core rod underwent stages of surface damage, damage increasing, fatigue embrittlement, matrix hydrolysis, and fiber fracture. Simultaneously, the silicone rubber sheath on the outer side of the composite insulator’s bending arc develops cracks over aging time, creating pathways for moisture ingress into the interface and core rod. The dielectric constant and dielectric loss factor of the aging region of the core rod increase to varying degrees compared to the non-aging part. Moreover, the degree of abnormal heating of the samples intensifies with the duration of aging experiments. These findings underscore the significance of understanding the aging and decay-like fracture process of compact line V-string composite insulators. They provide crucial insights for future research aimed at enhancing the material properties of composite insulator core rods.

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Section: Analysis and Discussionmentioning

confidence: 99%

Study on the Mechanism Effect of Bending Loads on the Decay-like Degradation of Composite Insulator GFRP Core Rod

Yi,

Ding,

Liu

et al. 2024

Energies

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“…The abnormal heating of composite insulators in operation is mainly attributed to the dielectric loss caused by the dielectric polarisation effect under the action of the frequency of the AC electric field and the loss caused by the leakage current [ 17 ]. A dielectric equivalent circuit model is shown in Figure 9 .…”

Section: Simulation Analysis Of Abnormal Temperature Rise Characteris...mentioning

confidence: 99%

Diagnosis Method of Decay-like Composite Insulators in a High-Humidity Environment Based on Characteristic Coefficient of Temperature Rise Gradient

et al. 2023

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At present, the temperature rise in insulators is observed using infrared thermometry as a common method of diagnosing decay-like insulators. However, the original characteristic data obtained by infrared thermometry cannot effectively distinguish some of the decay-like insulators from those with ageing sheaths. Therefore, it is imperative to find a new diagnostic characteristic quantity. Based on statistical data, this article first explains that existing diagnostic methods have limited diagnostic effectiveness and a high false detection rate for insulators in a slightly heated state. A full-scale temperature rise test is carried out on a batch of composite insulators returned from the field under high-humidity conditions. Two different defective insulators with similar temperature rise profiles are identified, and an electro-thermal coupling simulation model is developed based on the dielectric characteristic parameters of the above insulators for both core rod defects and sheath ageing. A new infrared diagnostic feature, the temperature rise gradient coefficient, is then obtained to identify the source of abnormal heat in insulators using statistical analysis of an infrared image gallery of abnormally hot composite insulators obtained from field inspections and laboratory tests.

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“…The importance of liquid permeation, and especially acid liquid, on the decay-like fractures of GFRE rods, has been recognized in previous research [ 21 , 22 ]. In addition, the “decay” characteristics shown in Figure 1 b suggest the severe degradation of the resin matrix, which cannot be the result of liquid immersion only.…”

Section: Introductionmentioning

confidence: 99%

Influence of Surface Discharge on Resin Degradation in Decay-like Fracture of Composite Insulators

Wang

Bao²,

Gao³

et al. 2023

Polymers

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Composite insulators have gradually become the preferred approach for electrical insulation in power systems, especially in polluted areas. Composite insulators consist of three main components: the shed, rod, and end fitting. Insulators withstand mechanical stresses via rods that are composed of glass-fiber-reinforced epoxy (GFRE). However, regardless of the high tensile strength of GFRE rods, in real-life operation, abnormal fractures have frequently been reported all over the world, which substantially increase the risk of major accidents in power systems. Fractural accidents mainly consist of brittle and decay-like fractures, which exhibit rather different morphologies at the cross sections. Brittle fracture has been effectively eliminated, while the mechanism of decay-like fracture has still not been clearly revealed. In this study, surface discharge tests were applied to investigate the discharge influence on the degradation of GFRE. The test successfully simulated the composition variation of the rods in real-life composite insulators with decay-like fractures. Moreover, it confirmed that the distinction between the characteristics of brittle fracture and decay-like fracture stems from epoxy degradation due to hydrolysis and carbonization. In addition, the respective influences of the resin type, glass fiber type, and acid liquid immersion on the degradation process were probed, and the degradation mechanism proposed in this research was verified. Based on the results, measures for preventing the development of decay-like fractures in real-life operations were determined.

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Study on the influence mechanism of ambient humidity on the temperature rise of decay‐like composite insulators

Cited by 11 publications

References 15 publications

Study on the Mechanism Effect of Bending Loads on the Decay-like Degradation of Composite Insulator GFRP Core Rod

Study on the Mechanism Effect of Bending Loads on the Decay-like Degradation of Composite Insulator GFRP Core Rod

Diagnosis Method of Decay-like Composite Insulators in a High-Humidity Environment Based on Characteristic Coefficient of Temperature Rise Gradient

Influence of Surface Discharge on Resin Degradation in Decay-like Fracture of Composite Insulators

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