I would say this is more of a general inquiry for a high torque top drive, there is potential for an upgrade to accommodate larger drillpipe torque demands and it would be helpful to know why certain ones are preferred versus another (although they may all look acceptable/good on paper).
This Hart Energy article
on top drive motors was very insightful. Not to say that there would even be the option for changing what's in the box as far as available top drive offerings are concerned (despite everything being a time and money problem), but if the built in motor motor fails, perhaps because the blower cooling system was clogged with dirt which led to an overheating, just basic maintenance and servicing would reduce that likelihood. If the cooling system was an internal water cooling, perhaps it'd be a non-issue completely. As a real life example, a blower motor has failed on us - an air filter clogged which led to a motor burnout, ultimately leaving our top drive dead in the water. Augusto:
Don't threaten me with a good time, I will be sure to read through these papers and post a follow up reply. I couldn't find the IADC/SPE 23854 paper, and for the record the H&P paper is filed under SPE 29394 at least in OnePetro. It is important to learn from history, if not we're bound to repeat it!