Comparative Study on the Thermal-Aging Characteristics of Cellulose Insulation Polymer Immersed in New Three-Element Mixed Oil and Mineral Oil
1
State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China
2
Nanjing NARI Group Corporation, State Grid Electric Power Research Institute, Nanjing 211000, China
3
Wuhan NARI Co. Ltd., State Grid Electric Power Research Institute, Wuhan 430077, China
*
Author to whom correspondence should be addressed.
Polymers 2019, 11(8), 1292; https://doi.org/10.3390/polym11081292
Received: 30 June 2019
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Revised: 18 July 2019
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Accepted: 25 July 2019
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Published: 2 August 2019
(This article belongs to the Special Issue Assessment of the Ageing and Durability of Polymers: Procedures and Reliability)
Cellulose paper, whose main component is cellulose polymer, has been widely used in oil-immersed power transformer that gradually deteriorates during transformer operation. Thermal aging is the main degradation form for cellulose paper immersed in insulation oil (oil–paper insulation) in a transformer. One of the most challenging issues in oil–paper insulation is inhibiting the aging of cellulose paper and extending its life. In this work, a comparative study was conducted on the thermal-aging characteristics of cellulose paper immersed in a novel three-element mixed insulation oil and mineral oil at 130 °C for 150 days. The key parameters of cellulose paper were analysed, including the degree of polymerization (DP), thermal-aging rate, surface colour, and AC breakdown voltage. The furfural content and acidity of the oil, as well as the AC breakdown voltage of the insulation oil were also analysed. The results show that the cellulose paper immersed in novel three-element mixed insulation oil had much higher DP values than that immersed in mineral oil after the same thermal-aging time. The mixed insulation oil could significantly inhibit the thermal aging of cellulose paper and prolong its life. The thermal-aging rate of the cellulose insulation polymer immersed in mixed insulation oil is significantly lower than that immersed in mineral oil, whether in the process of oil–paper insulation continuous aging or in the process of aging after oil replacement with unused insulation oil. The furfural generated by cellulose degradation in the novel three-element mixed insulation oil was also less than that in the mineral oil. The mixed insulation oil had a higher acidity value during the thermal-aging process, which was mainly due to the natural esters in the components of the mixed insulation oil. However, the AC breakdown voltage of the mixed insulation oil was always higher than that of the mineral oil. This study offers a new perspective in inhibiting the thermal aging of cellulose polymer in insulation oil.
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Keywords:
cellulose paper; polymer; mixed insulation oil; aging life; oil replacement; transformers
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MDPI and ACS Style
Feng, D.; Hao, J.; Liao, R.; Chen, X.; Cheng, L.; Liu, M. Comparative Study on the Thermal-Aging Characteristics of Cellulose Insulation Polymer Immersed in New Three-Element Mixed Oil and Mineral Oil. Polymers 2019, 11, 1292. https://doi.org/10.3390/polym11081292
AMA Style
Feng D, Hao J, Liao R, Chen X, Cheng L, Liu M. Comparative Study on the Thermal-Aging Characteristics of Cellulose Insulation Polymer Immersed in New Three-Element Mixed Oil and Mineral Oil. Polymers. 2019; 11(8):1292. https://doi.org/10.3390/polym11081292
Chicago/Turabian StyleFeng, Dawei, Jian Hao, Ruijin Liao, Xin Chen, Lin Cheng, and Mengna Liu. 2019. "Comparative Study on the Thermal-Aging Characteristics of Cellulose Insulation Polymer Immersed in New Three-Element Mixed Oil and Mineral Oil" Polymers 11, no. 8: 1292. https://doi.org/10.3390/polym11081292
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