Sealed tube testing
After completion of a long term thermal aging program, manufacturers may wish to add new minor components to the EIS. Such components include fastening tapes, tie cords, balancing compounds and other materials commonly used in mechanical applications. Rather than conducting another long-term thermal aging program to address the chemical compatibility of these minor components, sealed tube testing is conducted to quickly determine if the gaseous degradation by-products of these materials are detrimental to the performance of EIS's major components.
This test is conducted by sealing all of the tested materials along with the additional proposed materials in glass tubes. The materials are then aged for two weeks at the established system's temperature rating, plus 25 C. Following this process, dielectric strength testing is conducted on the magnet wire to determine if the new materials have caused any additional degradation. Although the actual sealed-tube conditioning lasts only two weeks, the investigation conducted in its entirety may take approximately six weeks to complete. This sealed-tube test program is aligned with a similar program proposed for inclusion in IEC 61858.