Multi-Factor Aging Mechanism and Multi-Parameter Synergistic Lifetime Prediction of HTV Silicone Rubber Composite Insulators

The long-term aging of HTV silicone rubber composite insulators under complex environments severely threatens power transmission line reliability. Traditional single/dual-parameter aging evaluation and lifetime prediction methods have low accuracy and poor generalization because they generally ignore multi-factor synergistic effects, pollution accumulation and electrical erosion. In this work, we systematically studied the aging characteristics of HTV silicone rubber under UV radiation, humidity, salt/ash contamination and their combined effects via accelerated aging tests and field sample verification, quantitatively analyzed the evolution of key mechanical, electrical and hydrophobic properties, and revealed the multi-factor synergistic aging mechanism from a micro–macro perspective with SEM, XPS and FTIR. The acceleration factor of the comprehensive accelerated-aging test was calculated as 43.8 through field-performance matching between 2000 h laboratory aging and 10-year field aging. We further established a “physical-pollution-electrical” three-dimensional evaluation system and constructed a multi-parameter synergistic lifetime prediction model through Pearson correlation analysis, VIF diagnosis and multiple stepwise regression. Compared with traditional dual-parameter models, the proposed model integrates physically interpretable degradation, contamination and electrical-stress indicators, thereby improving both prediction accuracy and engineering traceability. The model has 33% higher accuracy than traditional dual-parameter models, with average prediction errors of 0.55 years (same-manufacturer) and 1.0 years (cross-manufacturer). Five-fold cross-validation gives an MAE of 0.62 ± 0.08 years, and independent testing shows that most validation samples fall within the 95% prediction intervals, confirming favorable applicability within the present validation scope. These results provide theoretical and technical support for condition-based maintenance of composite insulators in power grids.