Another person called Geoff posts the same question - even with the same typographical errors - remarkable.
If the RCD trips some minutes after switching an element on you can be quite certain that the element is causing the trip... the resistance wire inside the outer case warms up and expands and touches the outer sheath.
So there's undoubtedly a fault with the oven element.
As for the Grill/RCD trip I can't comment - you do not say if it's an immediate trip or a delayed one.
Like you I do not think you have a problem with the RCD.
Unlike you I need to decipher your line...
and put the clock on allwas fibe
I think you mean the clock works correctly.
Good Luck...
November 2015