Now you are talking my kind of project. Just hope yours does not take the years mine does.
Sounds like you have all the details worked out. Except, what are you going to do with 550KW of power?
It's taking quite a while. I hope to have the PTO generator done before a year of dust settles on it, but the jeeperator is realistically part of my 5 year plan. I'm far from having all the details worked out. I don't even know how I'm going to step the speed up. I gave V-belts a good hard look again last night, and that's probably the way I should go. When I looked into it before, I was looking at pulley combinations that I could get from SuplusCenter, where the larger pulley was 18.75" (the biggest they have), which meant I would need several pulleys and belts in parallel. I looked on Ebay and found huge (used) pulleys in single and double belt configurations which would increase contact area and decrease belt stress, allowing me to use fewer belts. It still won't be cheap, but it will be closer to achievable.
I won't have 550kW of power. Or 275kW. Not even close. I should realistically be able to get maybe 20kW out of it (which is pretty close to all I need), coupled to my tractor. Coupled to the jeep, maybe 100kW in short bursts, but not sustained without overheating. If I wanted to get the rated 275kW from it, I would need to go buy the Caterpillar skid engine that goes with the generator head. The 30kW ST generator head that I was looking at before, would have served my purposes just fine. I have no use for 275kW of power. The benefits (as I see it) of using this generator head over the 30kW Ebay ST head are as follows:
1. The Cat head is Made in America. The Ebay head is made in China. I expect the American one to be more reliable.
2. I'll only ever be using it at (max) 1/10th of its rated capacity. It should last forever since it will never have to break a sweat.
3. Two for the price of one. If being made in America and being treated like a baby don't lend to longevity like I hope, I have a whole 'nother generator head to pull parts from. With any luck I'll never have to buy parts for this thing.
4. The huge rotating inertia of the rotor, while a burden to get started, once at speed should act as an extremely heavy flywheel to power through instant high power surges (like starting the home central A/C) without any flicker in the lights and irritation of electronic gadgets.
5. It's a 12-wire, 3phase generator. It can be configured for 3 phase or single phase output at 120V, 240V, or 480V output. The 30kW Ebay unit is just 120V/240V single phase. I may actually need that 3ph 480V capability for my day job. I build control panels for industrial installations. Right now I power them from a [RPC + transformer] but it pulls a LOT of juice from my residential service and makes my neighbors lights flicker. And I've never even done any real high power testing. If, for example, I ever need to do a FAT with a customer witness, this would be a much better way to go about it.
6. It's big and yellow and Caterpillar. It's impressive (to me, anyway). Not quite on the level of having a Corvette in your driveway, at least not in normal people's way of thinking. But in my nerdy way of thinking, it's super cool and I know that nobody else within a 50mi radius has anything like it.
What's this generator project of yours? Is there a forum thread about it? I'd like to see/hear some details.