Thermal Investigations on Service Aged Composite Traction Insulators

In the present investigation, the temperature rise study of composite insulators employed in the service for different aging durations in the traction system is performed. The test specimens taken from the service line with different duration of aging are subjected to artificial loss of hydrophobicity by dipping them in de-ionised water. Under the application of rated voltage, the leakage current is measured, and it is observed that the temperature is raised in the shank region with a differently aged insulator. For a completely failed insulator, it is observed to be higher and correlated with the leakage current. The rise in temperature is attributed to the fact of interfacial heating due to void and gap formation resulting from interface damage. Since these insulators are visually in normal condition but failed electrically. The non-linear behaviour of thermal rise with leakage current is found to be of key importance with the trapped heating zone at the interface. The current research work proposes an early detection of interface failure that can be performed by employing a non-invasive method that combines temperature rise detection by infrared thermography along with leakage current measurement.