In this paper

the issue that the H2content in insulation oil exceeded the normal value under non-fault condition in the invented current transformer was discussed. From the viewpoint of material properties

chemical reaction and molecular structure

the methods of thermodynamics and molecular structure dynamics were employed to research the origin of H2. It is considered that the content of H2in the invented current transformer with metal expander is higher than that without metal expander.Furthermore

the influences of insulation oil types on H2production rate are also discussed

and the analysis shows that the H2content tends to increase in the naphthenic base insulation oil.