Electrical insulating materials - Thermal endurance properties - Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time frame method
This part of IEC 60216 specifies the experimental and calculation procedures for deriving the
thermal endurance characteristics, temperature index (TI) and relative thermal endurance
index (RTE) of a material using the “fixed time frame method (FTFM)”.
In this protocol, the ageing takes place for a small number of fixed times, using the appropriate
number of ageing temperatures throughout each time, the properties of the specimens
being measured at the end of the relevant time interval. This differs from the procedure of
IEC 60216-1, where ageing is conducted at a small number of fixed temperatures, property
measurement taking place after ageing times dependent on the progress of ageing.
The diagnostic tests employed in the fixed time frame method are restricted to destructive
tests. The method has not as yet been applied to non-destructive or proof test procedures.
Both the TI and the RTE determined according to the FTFM protocol are derived from
experimental data obtained in accordance with the instructions of IEC 60216-1 and
IEC 60216-2 as modified in this standard. The calculation procedures and statistical tests are
modified from those of IEC 60216-3 and IEC 60216-5.