Molecular Dynamics Study of Moisture Migration Between Transformer Oil and Pressboard under Variation Temperature

Moisture has a significant effect on the insulation performance of the transformer. Some transformers have failed during rapid temperature ramp-up. When the temperature changes, the moisture will migrate between the oil and cellulose pressboard may form local high-moisture regions is considered to be a possible cause. But it has not been confirmed. It is difficult to validate this idea by experimenting because it is difficult to measure. In this paper, we tried to validate it by simulate the migration of moisture in oil and pressboard based on molecular dynamics. Molecular models were constructed to oil without water molecule and cellulose with 5% moisture by Materials Studio. The molecular dynamics simulations were carried out at a temperature ranging from 20°C to 80°C. The simulation results show that there are large amounts of water molecules accumulate at the interface of the oil-paper interface during the rapid temperature rise. This indicates that high moisture regions do occur at the oil-pressboard interface during a rapid rise in temperature for transformer.