Samsung oven tripping main fuse
Your oven's fan motor is shot -- replace it

It sounds like your oven's fan motor has a ground fault in it due to insulation breakdown (this is a common cause of motor failure -- its why insulation resistance tests are part of PM for heavy industrial motors).  I'd start by replacing the fan motor as this only happens if the fan is used.  If it continues, I'd keep hunting for the ground fault.