Hello, I have several changes of train when traveling from Luxemburgo to Lausanne. The first one is at 00:49 and two other changes. My question is if that’s only one travel in my Eurail pass or 3 travels. Please help!! Thanks a lot. 

A travel day is from 0.00 to 23.59 (possible to use as man, trains as you like). If you do change past midnight, it''s a new travel day.

So starting before midnight and changing past midnight twice (the same day) does mean two travel days (I think you'll go via Koblenz, arriving Lausanne 9.34).

But of course Luxemburg to Lausanne would be possible with one travel day if you do choose a daytime connection. It's also much faster.