Impact of local overheating on conventional and hybrid insulations for power transformers

Kassi, K. S.; Fofana, I.; Meghnefi, F.; Yéo, Z.

doi:10.1109/tdei.2015.005065

Cited by 26 publications

(18 citation statements)

References 20 publications

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“…Insulating materials only produce little gas when they are normal aging. But the discharge and overheating fault occur in the equipment, deterioration process of insulating materials is greatly accelerated to accelerate rate of biogas production of the above gas [25]. The study demonstrated composition and content of these gas has close relation with property of fault, these gases are called as characteristic gases, as shown in Table 1.…”

Section: The Methods For Dissolved Gases Detection In Oil-insulated Tmentioning

confidence: 95%

Experimental Analysis of Modified CNTs-Based Gas Sensor

Tang¹,

Zhang²,

Xiao³

et al. 2017

Electrochemical Sensors Technology

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As a significant equipment in power system, the operation condition of transformers directly determines the safety of power system. Therefore, it has been an indispensable measure to detect and analyze the dissolved gases in transformers, aiming to estimate the early potential faults in oil-insulated transformers. In this chapter, the adsorption processes between modified carbon nanotubes (CNTs) (CNTs-OH, Ni-CNTs) and dissolved gases in transformers oil including C 2 H 2 , C 2 H 4 , C 2 H 6 , CH 4 , CO, and H 2 have been simulated based on the first principle theory. Meanwhile, the density of states (DOS), adsorption energy, charge transfer amount, and adsorption distance of adsorption process between CNTs and dissolved gases were calculated. Moreover, two kinds of sensors, mixed acid-modified CNTs and NiCl 2 -modified CNTs, are prepared to conduct the dissolved gases response experiment. Then, the gas response mechanisms were investigated. Finally, the results between response experiment and theoretical calculation were compared, reflecting a good coherence with each other. The CNTs gas sensors possess a relatively high sensitivity and fine linearity, and could be employed in dissolved gas analysis equipment in transformer.

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Section: The Methods For Dissolved Gases Detection In Oil-insulated Tmentioning

confidence: 95%

Experimental Analysis of Modified CNTs-Based Gas Sensor

Tang¹,

Zhang²,

Xiao³

et al. 2017

Electrochemical Sensors Technology

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“…To optimize costs and performance, hybrid insulation materials combining aramid and cellulose have been proposed to provide incremental improvements in thermal stability. The results of some works performed on hybrid insulation have shown that this type of insulation not only allows to increase the operating temperature [135], but also retard the degradation of insulating oil [136]. Recently, ASTM has developed a new standard test method for tensile testing of Aramid-based paper published as D7812, to be used for quality control [137].…”

Section: Alternative Insulating Materialsmentioning

confidence: 99%

Review of Physicochemical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

et al. 2016

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Abstract:A power transformer outage has a dramatic financial consequence not only for electric power systems utilities but also for interconnected customers. The service reliability of this important asset largely depends upon the condition of the oil-paper insulation. Therefore, by keeping the qualities of oil-paper insulation system in pristine condition, the maintenance planners can reduce the decline rate of internal faults. Accurate diagnostic methods for analyzing the condition of transformers are therefore essential. Currently, there are various electrical and physicochemical diagnostic techniques available for insulation condition monitoring of power transformers. This paper is aimed at the description, analysis and interpretation of modern physicochemical diagnostics techniques for assessing insulation condition in aged transformers. Since fields and laboratory experiences have shown that transformer oil contains about 70% of diagnostic information, the physicochemical analyses of oil samples can therefore be extremely useful in monitoring the condition of power transformers.

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Section: Thermal Stress Simulationmentioning

confidence: 99%

“…In addition, currently, some publications applied the method of heating wires in oil to simulate overheating faults [24,25]; however, it was not easy to make fault point temperatures reach above 700˝C (T3 region) because of the limitation of the maximum power source and meltdown of heating wire as presented in these papers. The highest temperature that the heating wire can achieve was 600˝C in [24] and the experimental simulating temperature was 280˝C in [25]. In order to simulate high-temperature thermal faults and obtain fault gas data at high temperature, a specially-designed experiment system containing a pipe heater, a L-shaped stainless steel container, and a temperature controller were designed to simulate thermal faults at temperatures above 300˝C (300˝C, 400˝C, 500˝C, 600˝C, 700˝C, and 800˝C), as shown in Figure 1.…”

Section: Thermal Stress Simulationmentioning

confidence: 99%

Comparison of Dissolved Gases in Mineral and Vegetable Insulating Oils under Typical Electrical and Thermal Faults

Xiang

Zhou

et al. 2016

Energies

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Dissolved gas analysis (DGA) is attracting greater and greater interest from researchers as a fault diagnostic tool for power transformers filled with vegetable insulating oils. This paper presents experimental results of dissolved gases in insulating oils under typical electrical and thermal faults in transformers. The tests covered three types of insulating oils, including two types of vegetable oil, which are camellia insulating oil, Envirotemp FR3, and a type of mineral insulating oil, to simulate thermal faults in oils from 90˝C to 800˝C and electrical faults including breakdown and partial discharges in oils. The experimental results reveal that the content and proportion of dissolved gases in different types of insulating oils under the same fault condition are different, especially under thermal faults due to the obvious differences of their chemical compositions. Four different classic diagnosis methods were applied: ratio method, graphic method, and Duval's triangle and Duval's pentagon method. These confirmed that the diagnosis methods developed for mineral oil were not fully appropriate for diagnosis of electrical and thermal faults in vegetable insulating oils and needs some modification. Therefore, some modification aiming at different types of vegetable oils based on Duval Triangle 3 were proposed in this paper and obtained a good diagnostic result. Furthermore, gas formation mechanisms of different types of vegetable insulating oils under thermal stress are interpreted by means of unimolecular pyrolysis simulation and reaction enthalpies calculation.

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Impact of local overheating on conventional and hybrid insulations for power transformers

Cited by 26 publications

References 20 publications

Experimental Analysis of Modified CNTs-Based Gas Sensor

Experimental Analysis of Modified CNTs-Based Gas Sensor

Review of Physicochemical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

Comparison of Dissolved Gases in Mineral and Vegetable Insulating Oils under Typical Electrical and Thermal Faults

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