Now here is an unusual one. 55 Siggy 1:9 150 Design.
In all my years in the trade it has never concerned or interested how hot the alternator got and how quickly it warmed up.

BUT

Did the usual replacement at 55k with a refurbished example from a trusted source I used to use in the trade and never had problems with, I was under the bonnet doing the usual checks when I could smell that hot insulation smell. Put my hand close to the alternator and it was very hot.
Tried the temp when the engine was cold and just after about 5 mins of running the alternator seemed on the warm side, (hotter than the engine).
I realise these are 100+amp alternators, and by virtue of that they will tend to get a bit warm but wondering just how hot these things are meant to get.