Based on the site conditions, preliminary suspicions include slight contamination on the insulator surface or early damage to the glaze layer; mild fouling on the conductor surface or slight loosening of the binding wire clamps; a slight decrease in the vacuum level of the arc-extinguishing chamber or localized electric-field concentration on the bellows screen; aging of the bushing sealant and minor corrosion at conductive parts; loosening and oxidation of the terminal connections, or displacement of the grading ring. Accordingly, it is recommended to: continuously monitor for suspected issues; maintain quarterly repeat testing; record trend data monthly; take advantage of the next scheduled outage window to shorten the monitoring interval to monthly; and, depending on changes in magnitude, temperature, and other parameters, schedule outages for cleaning, replacement, inspection, re-tightening, surface protection, vacuum-level verification, and dielectric-strength testing.
Results & Value
• Completed a 3-km line scan in 30 minutes, identifying five partial discharges.
• Live-line operations ensure uninterrupted power supply.
• Estimated to prevent a single breakdown-induced power outage, thereby recovering 80,000 kWh of electricity.
