Thanks for the phase converter link; I'll ask for their input today.
I had one vender research all of my options, which include an add-a-phase transformer, a soft-start unit, and a VFD. His results brought him back to the VFD. It looks like the Yaskawa brand is the most economical approach; it's smaller than I thought it would be at 21" tall x 10" wide x 10.25" deep.
One vendor said that I needed line reactors because of the single-phase input, but my best vendor source said that line reactors are only necessary if the power line is dirty or if the power is a very long run.
I only got one price for a 15HP 1-Ph pump, two pump vendors are still looking and three other pump vendors said that there's no such motor for a close-coupled end-suction pump, that 15HP 1-Ph motors are only available for submersible (turbine well) pumps.
P.S. I read the posts regarding adding a motor to covert to three-phase. If this application were for me personally, and if I had the space, I might pursue this option. The 15HP pump will be in a fiberglass underground vault that is about 5'-7" x 6'-4" in plan view. This is for a fountain with off/on controls by a simple digital timer. This fountain will probably (hopefully) be visited by the maintenance guy once or twice a week.
[This message has been edited by FountainGuy (edited 03-24-2006).]
