I assume you mean the power fuse for the main radiator fan at the front of the car?
This could be a motor fault.
I say this because when we had our Coupe 20V (non turbo) then when driving through the very very hot south of France with aircon at full blast when we came to a toll and stopped the radiator would suddenly overheat and blow boiling water out. Found that motor fuse had blown but by driving there was sufficient airflow to cool the car so the fault went unoticed. Replaced the fuse, topped up the rad and it happend again at another toll. Fortunately when we got to Italy and up into the Dolomites temperatures were much cooler. No further problems for the three weeks we were away. Similary on the way home through Austria, Gernmany & Belgium cooler and no problems.
After the 1st Maxi 50Amp fuse blew the first thing I did was buy a bunch of spares.
Back in the UK it never happened again despite trying to stress the cars cooling. I eventually replaced the radiator fan and put the old one up in the garage loft as an emergency spare.
I never did find what was wrong with the orignal fan / motor. Was either an insulation / winding failure at very high temperatures or the motor was binding and pulling excess current.