Analysis of Resin Impregnated Non-woven : In collaboration with Hitachi Energy

Sammanfattning

High voltage bushings are the most critical components of power transformers. A common material used in bushings is resin impregnated paper (RIP). Hitachi Energy is investigating whether this can be replaced with a new material, resin impregnated non-woven (RIN). One of the main reasons is that non-woven is less prone to absorb moisture compared to paper. Thus, for design purposes the mechanical, thermal and absorption properties of RIN have been studied and compared to RIP. The mechanical properties were tested by tensile and bending tests at room temperature and 80 ℃, showing that RIN has a lower elastic modulus and tensile strength than RIP at both temperatures. However, it was demonstrated that RIN does not retain its elongation at break and elasticity properties at elevated temperatures. The bending test showed no significant differences in flexural properties for RIN between room and high temperature. The thermal properties were studied with the transient plane source method (TPS) showing that both RIN and RIP had a higher specific heat capacity than pure epoxy. The thermal conductivity of the materials will be measured and included later. Lastly, the water absorption test was performed in order to provide information about the suitability of the materials used in bushings. For this different methods were used; water immersion andwater vapor testing. The immersion test showed that non-woven is more water resistant than paper and that the composites only absorb a small amount of water. No useful information was achieved from the water vapor test due to limited testing time. The results demonstrate the promising potential of RIN in bushings.