Many 3 phase electric motors can be wired for for high voltage 440-480v, or low voltage 208-240v. But the configuration of the wires change, usually at the motor, depending which voltage you need.
If you have 6 connections, it is possible that this is where you would need to jumper some together, for either high or low voltage. Or maybe 3 connections are for lathe motor, and 3 are for coolant pump or the like. You would need to trace the wires for the 6 connections to where ever they go to know.
5hp motor, is most likely started through a contactor. With a start switch activating the contactor. Is the lathe set up for forward and reverse, or only forward ?
The absolute thing you need to do is determine if the motor is wired for high or low voltage, and that will most likely be at the motor itself. And there may be a print on the motor tag or inside the small connection box at motor to show high or low voltage. Or the tag may only list one voltage. But you most likely need to open the small connection box at motor itself to check how wires are connected inside. The wires will have numbers on them.
If your convertor is using an idler motor to generate the 3rd leg for 3 phase, this is a rotary phase convertor, or rpc. Is this low voltage, 208-240v ? Most likely yes, just confirming.
After you know what voltage the motor is wired for, physically trace the wires to where they go. And trace wires from the connection box, and where they go. Maybe draw us a small basic print.
