Residual Stress in Epoxy-Based Insulators: Formation, Detection, and Reliability

Area of Science:

• Electrical Engineering
• Materials Science
• Polymer Science

Background:

• Gas-insulated switchgears (GISs) and gas-insulated transmission lines (GILs) are vital for high-capacity power transmission in challenging environments.
• Ultra-high voltage (UHV) epoxy-based insulators, critical for insulation and support, are prone to high internal residual stress.
• The lack of reliable detection methods often leads to equipment commissioning with undetected defects.

Purpose of the Study:

• To examine the formation mechanisms of curing deformation and residual stress in oversized epoxy-based insulators.
• To comprehensively summarize and compare current residual stress measurement techniques.
• To analyze the impact of residual stress and filler sedimentation on insulator mechanical reliability throughout their lifecycle.

Main Methods:

• Cure kinetics and thermo-chemical coupling models to understand stress formation.
• Review and comparison of embedded sensors, direct mechanical measurements, and non-destructive testing (NDT) for residual stress measurement.
• Coupling residual stress analysis with filler sedimentation to evaluate stress distribution and mechanical reliability.

Main Results:

• Detailed examination of residual stress formation mechanisms in oversized insulators.
• Comparative analysis of the applicability and limitations of various residual stress measurement techniques.
• Insights into stress distribution patterns and mechanical reliability influenced by residual stress and filler sedimentation.

Conclusions:

• Understanding residual stress formation and measurement is crucial for UHV epoxy-based insulators.
• Accurate assessment of residual stress and its interaction with filler sedimentation enhances mechanical reliability predictions.
• This review provides theoretical references for improved structural design, process optimization, and performance evaluation of UHV power equipment.