SEDIVER Research Center presents a technical paper from Jean Marie George – Scientific Director and Sandrine Prat – PhD Research Manager
Wildfires can have multiple causes. Overhead lines often just happen to be on the path of a fire, and in this case, it is critical to understand what may happen to the line and its components. Besides the risk of having phase ground faults resulting from intense arcing activity in the smoke and heat cloud, resilience is paramount and the amount of damage to lines is a direct consequence of line designs. Distribution overhead lines are obviously much closer to fires than transmission lines and therefore suffer much more of heat damage. Wood poles are clearly identified as a weak link under such circumstances, but insulators can also become critical. Even for transmission lines the heat impact can be substantial but not necessarily immediately visible in the short term. Some specific physical characteristics of overhead line insulators need to be clearly identified and taken into consideration either to evaluate the risk of having a line drop during the fire or years later as a result of a weakening of the insulators which survived the fire in the first place.
Another aspect of this problem is to review insulator design features assessing the risk of insulators to be a threat triggering fires on a normal day. Insulator failures can lead to line drops and subsequently trigger fires and catastrophic situations. This is true for either distribution or transmission lines. Hardening the grid means finding more robust line designs and insulators.
In the aftermath of the Californian fires, this contribution is intended to help evaluating what can be done differently and what needs to be changed in the selection of insulators.