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ORIGINAL PAPER

Temperature effect on the thermal properties of insulation paper Chuan Luo1,2 · Zhengang Zhao1,2 Jiahong Zhang1,2

· Dacheng Zhang1,2 · Chuan Li2,3 · Chang Liu1,2 · Yingna Li1,2 ·

Received: 4 December 2019 / Accepted: 20 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Establishing and optimizing a distributed parameter thermal path model for transformer windings is an important means to analyze the hot-spot temperature of the windings; furthermore, in the process of improving the thermal path model of transformers and improving the accuracy of their models, the thermal characteristics of the insulation paper are extremely important. A microscopic thermal contact resistance model was established for the contact interface of insulation paper and copper, according to the microscopic morphology parameters of copper and insulation paper observed by atomic force microscopy, the thermal contact resistance under different temperatures was calculated. A dual heat flow test platform was built to test the heat transfer behavior of four different thickness insulation papers under four temperatures, and the thermal contact resistance and thermal bulk resistance with temperature were analyzed. The results show that as the temperature increases, the thermal resistance of the insulation paper becomes larger and the thermal conductivity decreases. The average error between the experimental and theoretical values of the thermal contact resistance under four temperature points in the study is 6.6%. The results provide a data support for establishing and optimizing transformer heat generation and heat transfer models. Keywords Insulation paper · Thermal contact resistance (TCR) · Thermal bulk resistance (TBR) · Microcontact surface · Double heat-flux meter

1 Introduction The development and operation of ultra-high-voltage and large-capacity power transformers requires to solve an important problem which is about excessive local heat in the transformer. Winding losses and core losses generate a large amount of heat, which will accelerate the aging rate of the insulation paper. The oil-immersed transformer is A-class insulation, and the maximum operating temperature of winding is 105 °C. If it is operated at the extreme temperatures for a long time, it directly leads to a decrease in insulation per-

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Zhengang Zhao [email protected]

1

Faculty of Information Engineering and Automation, Kunming University of Science and Technology, Kunming 650500, Yunnan Province, China

2

Yunnan Key Laboratory of Computer Technology Applications, Kunming University of Science and Technology, Kunming, China

3

Kunming Intellight Measurement Science and Technology CO., LTD, Kunming, Yunnan Province, China

formance, which seriously threatens the life cycle and safe operation of transformer. The transformer winding hot-spot temperature is a key parameter to define the power transformer thermal conditions and overloading capability [1–4]. The equivalent heat circuit of the thermal model for a