According to the goals, thoughts and tasks of 973 Program, two scientific problems are summarized in this topic:(1)Mechanisms, modeling and simulations of VFTO;(2)failure mechanisms and insulation characteristics of GIS stressed by VFTO. The main content of the topic focus on the scientific problems above is: Basic research is a driving force for the progress of human civilization,a source and backbone of S&T and economic development, VFTO measurement have been carried out in UHV substations based on the de...