Bostomatic 400-3 - Converting power from 480V to 240V

[nduerr]

I came across a deal on a 1989 Bostomatic 400-3 with 2 spindles & 4 axes this past fall. It was converted to PC controls in 2004 so I hope It will start up and work! I have it all setup and leveled in my garage and I am working on wiring it back up. It was originally setup for 480V but the wiring diagrams show a 240V option also. I reconfigured the hydraulic pump motor and coolant pump motor to run on 240V just need to check rotation direction after startup.
There are 4 transformers, 3 isolation/step down for the main spindle, secondary spindle and 120V power. The last one is a Delta Wye transformer to 82V for the servo drives.
I believe I have the 3 isolation/step down transformers figured out and have disconnected the output to test voltage after power up. I am not sure I need 2 of them, they will be 240v 3ph to 240V 3ph but for now I will leave them connected.

The one that is giving me problems, is the 82v Delta Wye. I have the diagram but the 240V wiring is not clear see attached pic, specificity what leads to remove, if any, from the 4 input posts of the 3 coils.
Can anyone clarify the wiring on the input side?
Thanks,
Nick

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[Jim Dawson]

That is a bit hard to follow but I think the following is correct.

Remove the 5-6 jumper, connect 5 to 4, connect 6 to 7

Remove the 8-9 jumper, connect 8 to 7, connect 9 to 10

Remove the 11-12 jumper, connect 11 to 10, connect 12 to 4

Draw that up and compare to the dashed lines to confirm.

Looks like it can all be done at the terminal strip 02-5TB

[nduerr]

That looks like a winner to me. I will give it a try this weekend. I was wondering what the 02-5TB on the diagram was, I will have to go back and look at the other transformers to see if I should be changing the terminal blocks instead of the transformers.
Thanks Jim.

[nduerr]

Everything measured the correct voltage after the wiring change. I am ready to start up the machine.
Thanks again Jim.