Effects of BTDA Crosslink on DC Surface Discharge Characteristics of EP/Glass Composite for Smoothing Reactor

The smoothing reactor is prone to surface discharge at the end of the junction between the star frame and external insulation. To enhance the dc surface discharge voltage of the cladding insulation of the smoothing reactor, 3,
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-diphenylketetracylic anhydride (BTDA) is used to enhance the molecular chain crosslinking degree of epoxy/glass fiber (EP/glass) composites, and Fourier infrared spectroscopy, surface trap distribution, surface charge distribution, surface conductivity, and surface discharge voltage of modified fiber were conducted, and influence mechanism of BTDA on the surface flashover of EP/glass composites was clarified. The findings demonstrate that the surface discharge voltage increases to its maximum level with a 15 wt% addition of BTDA, which is 17.3% higher than the value for pure EP/glass material. The FTIR results illustrate a small amount of BTDA agent can introduce the carbonyl groups and improve the crosslinking degree of epoxy resin. The carbonyl groups can effectively improve the trap level and density of the EP/glass composites, forming a coulomb shield to inhibit the accumulation of surface charge, reducing the surface conductivity, and improving the surface discharge voltage. Excessive BTDA modification will make the orbital degeneracy of the outermost electrons of the polarity group, reducing the trap energy level and density and causing the buildup of surface charges, finally improving the surface conductivity and reducing the surface discharge voltage. This study provides a reliable route to raise the surface discharge voltage by directly promoting the crosslinking of molecular chains of polymer composites.