Don't need a three-phase...
Hi David!
You don't need a three-phase in 1.5kva... and you'd probably be alright with 1kva...
lessee... 1kva @ 240v is about 4A... using three single-phase transformers, that's a whole lotta power for a 3/4hp motor...
Take a look at the motor plate and see how many Full Load Amps it draws at 440-480... multiply that by two to get FLA at 240v... and then multiply that to get VoltAmpres...
and then divide that by three to determine how many VA you'll need in each of a trio of single-phase transformers.
One other way to accomplish it, is to get a 440v Variable Freq drive... about 2hp... and feed it with just ONE 240-480v transformer (backwards- line to the 240v side, 480 out the other end, to the VFD) and call it done... much less iron involved, and you get variable-speed, forward-reverse, and dynamic braking to boot!
I've been doing quite a bit of this kind of thing lately... For what it's worth, you should be able to find a good used transformer for under $50, and a 2hp 440 VFD for under $75... check HGR's website for transformers, and E-pay, and any of the drive warehouse places for VFDs. The solution shouldn't cost you over $150.