Research on thermal aging characteristics of silicone rubber composite materials for dry-type distribution transformers

To enhance the long-term operational stability of transformers, this study focuses on silicone rubber composite insulation materials for dry-type distribution transformers (D-DTs). Based on obtaining the optimal initial performance of silicone rubber composite materials through response surface model, the thermal aging characteristics and long-term stability of intrinsic silicone rubber and silicone rubber composites are compared using molecular simulations, thermogravimetric analysis, and accelerated thermal aging tests. The results indicate that the addition of a small amount of h-boron nitride (BN) and Al2O3 can improve the thermal stability of the composite materials, and the decline in elongation at break is the key factor determining the thermal lifetime of silicone rubber. The silicone rubber composite material doped with 21.42 phr h-BN, 1.58 phr carbon nanotubes, and 2.67 phr Al2O3, based on the optimal initial performance, is projected to have a lifetime of 3,128 h under accelerated thermal aging at 200 degrees C and 27.40 years under stable operating conditions of D-DTs, making it suitable for widespread application.