Assessment of Insulation Aging Condition for Dry-Type Transformer Epoxy Resin Based on Dielectric Response and Activation Energy Analysis
Year: 2025
Type: article
Abstract: The accurate assessment of the aging state of epoxy resin insulation is critical for the safe operation of cast resin dry-type transformers. This study investigates the evolution of activation energy during thermal aging and its correlation with insulation degradation. Accelerated aging experiments at 150 °C, 170 °C, and 200 °C were conducted, followed by frequency-domain dielectric spectroscopy and Havriliak–Negami (HN) model analysis. An improved method for calculating activation energy, incorporating temperature correction via an HN-based model, is proposed. The evolution of key HN parameters—relaxation strength (Δε), relaxation time (τ), and shape parameters (α, β)—serves as the criterion for identifying the dominant aging mechanism: crosslinking at 150 °C, competition between crosslinking and degradation at 170 °C, and degradation-dominated chain scission at 200 °C. Using 150 °C data as a baseline, the initial activation energy is determined to be 90.03 kJ/mol, increasing to 166.83 kJ/mol at the end of service life. A practical, graded insulation condition indicator based on the rate of change in activation energy (ΔEa) is established, providing clear guidance for maintenance decisions—from routine monitoring (ΔEa ≤ 20%) to prioritized inspection or replacement (ΔEa > 60%). The proposed method offers a non-destructive tool for insulation diagnosis, residual life prediction, and condition-based maintenance of dry-type transformers.
Source: Energies
DOI: 10.3390/en19010144
Authors: Yu Dong, Youhang Wang, Zhiqiang Li, Ning Lei, Yanchen Wei, Bin Song
Institutions: Suzhou Research Institute, Wuhan University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7117478288