Porcelain insulators are typically exposed to surface discharge and lightning impulse in service. This study investigates the insulation characteristics of the external and internal discharges of a porcelain insulator with respect to its flashover for a 154 kV transmission line. The experiments are also conducted using a wet flashover test and an impulse test based on the external discharge and the internal penetration, to classify the flashover voltage-time curve of the porcelain insulator. When an impulse with a strength of 2,500 kV/μs was applied three times to 6.5 mm ceramic samples, electrical penetration of approximately 70% occurred. The impulse experiment confirmed that the electrical penetration inside the porcelain insulator coincided with the area where the electric field was concentrated. The wet flashover voltage test revealed that the flashover threshold voltage increases by approximately 7% after cleaning of the surface.

Citations

• Highly Sensitive Partial Discharge Sensor with Remote Monitoring Capabilities
  Kyoo-Nam Choi
  The Journal of the Korea institute of electronic communication sciences.2015; 10(3): 349.     CrossRef
• Harmonics Analysis of Leakage Current due to Artificial Contamination of Distribution Arresters
  Jae-Jun Park
  The Transactions of The Korean Institute of Electrical Engineers.2012; 61(9): 1306.     CrossRef