Evaluation of electrical insulation properties on aged composite insulators in heavily contaminated areas

The usage of silicone rubber insulators in various contaminated areas has increased prominently in recent years in China, and it still keeps this increasing trend. As the energized time in the field is prolonged, the change of hydrophobicity and the accumulation of pollution directly affect the electrical insulation performance of composite insulators. This paper reports the electrical insulation properties on aged composite insulators based on a full-scale investigation, including the classification of hydrophobicity, the measurement of ESDD and NSDD, and the visual inspection of deterioration of polymeric materials. A new voltage withstand test of long duration in a fog chamber was introduced to study the anti-pollution flashover abilities of aged samples. The accumulation of pollution on insulators energized over a period of years and some external factors were found to be adverse for the hydrophobic transfer and recovery. In addition, all test results showed that the anti-pollution flashover abilities of samples were fairly well even though they had been energized for many years in heavily contaminated areas