Hey. I found something like this in help.

I made few tests. General conclusion is that STEP format is better for importing big objects. For example IGES failed with surface 250x50m and with STEP there is no problem.

After enabling large model support I was able to import 1000x1000m surface via STEP file into Design modeler. But nothing bigger then that. And according to help there shouldn't be no problem even with surface 1000x1000 km. Any ideas why is that ?

This problem is regarding only to Design modeler. I've imported step file with 10x10km surface to SpaceClaim and it send it to mechanical without any problems.