Monitoring and prediction of thermal failure of high-voltage switchgear insulation materials by studying the thermodynamic properties of FR-4 epoxy resin and the characteristic gas of thermal decomposition

Abstract

FR-4 epoxy resin is a common material used as internal parts in high voltage switchgear. In this paper, we adopted the accelerated thermal aging method to explore the thermal aging behavior of FR-4 epoxy resin, simulating the practical application of this material in high voltage switch. The effects of thermal aging on the thermodynamic properties and thermal decomposition characteristic gases of FR-4 epoxy resin were characterized by FT-IR, DSC, TG and GC-MS analyses. The experiment results showed that thermal aging could destroy the internal crystal structure of FR-4 epoxy resin, which could lead to this material easier to be decomposed after heating. We also detected that the thermal decomposition rate of FR-4 epoxy resin aging was greatly accelerated compared with the materials that had not been aged. In addition, unaged FR-4 epoxy resin could release 9 main volatile gases under 120°C, and irreversible defects or structural damages occurred in the materials along with the volatilization of small organic molecules. Furthermore, after continuous thermal aging at 120 °C for 672 h, the molecules of FR-4 epoxy resin were more cracked and volatilized, we observed a more obvious phenomenon of thermal decomposition in this materials. In total, we compared the types of thermal decomposition gases and the decomposion mechanism of aged and unaged FR-4 epoxy resin. In application, our results can provide reference for condition monitoring and fault prediction for this material in high voltage switchgear in the future.