IEC 60216-8:2013 specifies the general ageing conditions and simplified procedures to be used for deriving thermal endurance characteristics, which are shown by temperature index (TI) and/or relative temperature index (RTI) and the halving interval (HIC).
DS/EN 60216-8:2013 history
2013DS/EN 60216-8:2013 Electrical insulating materials - Thermal endurance properties - Part 8: Instructions for calculating thermal endurance characteristics using simplified procedures