Investigation of Ageing Factors and Long-Term Reliability in synthetic air-insulated switchgear

This paper evaluates its long-term reliability by examining gas sealing performance, material compatibility with decomposition gases, and lubrication characteristics. For gas sealing, EPDM

O-rings were assessed for boundary and permeation leakage. Accelerated ageing tests and equivalent temperature calculations confirmed O-ring lifetimes far exceeding the equipment's 40 - 50 year expected life. Calculated gas leakage rates for GCBs and SAs were well below the

IEC standard (0.012-0.025%/year vs. 0.5%/year), ensuring stable gas pressure. Decomposition gases (NOx from current switching, O3 from partial discharge) were studied. Material exposure tests showed only minor, practically acceptable changes in components such as grease and Orings. Health risk assessments (IEC 62271-4) indicated no risk in normal operation, with NO2 posing a concern only in abnormal leakage or maintenance. Lubrication evaluation focused on urea-based grease degradation and silver plating wear. Accelerated thermal degradation and

Pin-on-Disk (POD) tests showed that while degraded grease reduced abnormal wear cycles, the overall lubrication performance still met the 40 - 50 year expected service life, even under severe conditions.