Properties of transils

Hello!

I need information about values of the rms current which don't result in the open-circuiting of a transil diodes type SM6T and 1.5KE and about values of I2t  for these devices.

I need this informations to determine the fuse for transil to avoid the possibility of destroy the transil in the manner of destruction it'contacts (open circuit).

I want to eliminate the risk of transil diode becoming an open circuit after a pulse overload and continous current overload.

I'll be very gratefull for all informations which will help me to solve this problem.