Moisture and temperature effects on power transformer winding clamping pressure

Abstract

This paper presents findings from a finite element modelling based simulation study conducted to understand the moisture and temperature dependency of power transformer winding clamping pressure. Set of laboratory experiments were used to measure moisture dependent mechanical properties of high-density pressboard. First, 400 kVA disc type transformer winding was simulated to separately study the effects of moisture and temperature on clamping pressure. After that, fluctuations in clamping pressure under the combined effects of moisture and temperature of a field-installed autotransformer were studied. Simulation results revealed that winding clamping pressure is highly dependent on both temperature and moisture content. Finally, it was concluded that inclusion of moisture and temperature effect is important when analysing the results of winding clamping pressure estimation techniques.