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Temperature dependent mechanical properties of pressboard in transformer winding structure

Condition monitoring of power transformer winding clamping system is a topic with timely value and utmost importance. However, lack of understanding of temperature dependency of winding clamping system has prevented the development of reliable condition monitoring techniques to estimate the condition of power transformer winding structure. This paper presents the results of a FEM based simulations combined with laboratory investigations conducted to understand the temperature dependency of power transformer winding clamping pressure. Base on laboratory investigations and simulation results, it was found that power transformer winding clamping pressure is temperature dependent. Further, even though presented simulation results showed a good agreement with laboratory test results, comprehensive investigation of thermal expansion coefficient and thermal conductivity of pressboard is essential to improve the accuracy of FEM simulations.