Current transformer is a key contact component between the primary and secondary system.With the rapid development of grid construction in the West of China

strict requirement on the insulation design of current transformer is raised due to severe external environment

especially the influence to the insulation strength of current transformer by high altitude

high and cold condition and big day and night temperature in the Northwest area. In this paper

throughout the analysis of metal expander explosion and fire of current transformer of train traction transformer

which leads to power off

it is found that the equipment has the problem of incomplete drying

corresponding preventive measures are proposed so to avoid the occurrence of the similar fault in the future.