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3phase to single phase conversion with transformer for equal line currents

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ZeroResistance:
Is there a way to convert 3 phase 400V input to single phase, basically the output needs to be used for spot welding, and currently a transformer with single phase transformer is not working out well due to mains voltage dips while welding.
I would like to convert 3 phase to 1 phase with equal loading on the 3 phase input (equal current drawn from all lines). The power rating of the transformer would be 10kVA.
TIA

sibeen:
I don't think you can end up with a totally balanced three phase supply. Have a look at the Scott transformer connection.

Brumby:
The simplest method would be a motor-generator setup.  A 3 phase motor driving a single phase generator.

An electronic solution would involve taking each input phase, rectifying them to a common DC point and then using this DC to drive an inverter.

There was a thread on the "Dodgy Technology" board discussing a "digital electricity" product which would seem to do something of what you asked - but the person who was providing details tried talking to us in "marketing speak" and couldn't give any sort of straightforward answers to some key engineering questions.

IanB:
If your output doesn't need to be AC, you could use a three phase step down transformer and rectify the output. If course, the size of the required rectifier might be make it uneconomical. On the other hand, how are you switching the current for spot welding? Maybe you could combine switching and rectification in the same device?

ZeroResistance:
Thanks for all the replies.

I found some other transformers apart from Scott as suggested by sibeen.

1. Scott T
2. Open Delta
3. Le-Blanc

The story so far is I purchased a single phase 8KVa spot welder but it wasn't welding 0.25mm GI strips although it was welding 0.5mm MS strips at full power.
This was probably due to excess draw on the mains input and droop in line voltage (this is a guess).
I want to move to a 2 phase or 3 phase input transformer so I can get good performance. I may have to ask the manf to redo the transformer and some changes to his thyristor power module.
I don't know how many changes will the manf accept and how much time he would take to do it.
Now I want to move to a 10KVa, 2 or 3 phase input transformer.

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