Two-phase cooling technology is gradually becoming a solution for the heat dissipation bottleneck of high voltage power electric and electronic device. However

in case of high voltage application

the issue of insulation due to the boiling bubble needs special attention.As for the boiling characteristic in the two-phase cooling condition

mastering the insulation characteristic of refrigerants in liquid

gaseous and two-phase condition is the base for the development of insulation analysis of the two-phase cooling technology. However

the existing study does not yet have systematic method for multi-phases insulation test of the refrigerants. Therefore

the insulation experimental device for multiple phase conditions of refrigerants is developed and the dielectric strength test for the liquid vapor of low boiling liquid is achieved for the first time. Then

the breakdown experimental scheme for the vapor and two-phase flow of refrigerant is proposed. The systematic breakdown characteristic study of the liquid

gaseous and two-phase condition is developed by the use of FC-72 refrigerant. The dielectric strength of FC-72 vapor under various pressures and the breakdown test result at its two-phase condition is obtained. The breakdown mechanism at a two-phase condition is analyzed with combination of the behavioral characteristic of the bubble at electric field. Finally

the evaluation method of insulation threshold of two-phase gap with vapor dielectric strength as base is formed.