Turn the oven without any problem it works fine for about 15 minutes then trips the RCD in the fuse box the oven is 4 years old

Alan Bradley, February 2016

If it is the fan oven tripping the RCD, this may be the part:

http://www.partmaster.co.uk/cooker-oven/samsung/fan-oven-element-1800w/product.pl?pid=3240733&path=78825,574528:574546&refine=element

XXX, February 2016

The element has a resistance wire inside it - surrounded by insulating material - then the outer cover.

As the resistance wire heats up it expands - at some point - after 15 minutes the resistance wire in your element touches the outer case and the RCD trips.

If you restrict your cooking to 14 minute periods you should be OK.

Good Luck..., February 2016