Effect On Giving Two Phase 415 Volts Supply Instead of Single Phase and Neutral

The loads simply need redistributing across the phases so that the B phase current approaches that of the other two phases. That way, the generator won't trip so often on the current in the B phase.

Everything else seems in order from the description given, in principle. Make sure that all circuit protection equipment is working correctly, and correctly adjusted.

Did you try a 3ph to 2ph transformer?.

Please explain.

It looks like all you need to do is reconfigure your units to better balance the load over the three phases instead of just dividing them up by an equal number of units per phase.

As far as the harmonics and line distortion are concerned adding a few power correction capacitors across each phase near the most used machines would likely help clean things up a bit.

Can I ask a stupid question? Where on the face of this planet is there such a supply as 415VAC single phase?

It is mfd. by "American Chowel Industries" just google "chowel spot welding machine" you can go to their web site.

Everywhere that uses a 240/415 three phase power system. In the US it's not uncommon to find machines rated for 480 single phase inputs and some parts of Canada can even have 600 volt single phase.

Connecting across any two phases while leaving the third unconnected is still a single phase connection.

OK so this may just be pedantics. In Australia this is called a two phase system. A single phase system has return to neutral. There is no return to neutral therefore is two phase not single phase.

the question as i understand it - pls correct me if im wrong - is instead of 415v to neutral, OP has 3 phase of 415Y/240 v and he wants to connect 240 on one phase to 240 on another phase, producting 415 between the two phases. this works fine, it just needs re-balancing.

Install a 3phase to 1 phase transformer of sufficient capacity.

Just connecting 15 welding units on each leg of the 3-phase power supply may be the cause of your problems due to the following reasons;

1. Welder ratings varies between 75 to 150 KVA - You need to check the total KVA load for each phase, be sure they are are equal. Do Not use the quantity of welders (no. of welding units) as the basis of your load distribution..

2. Check that all welding units are being turned ON and use when you do your measurements and loading analysis.

It is very possible that your problems are caused by the above 2 scenarios or situations?

Technically this is a 415V, 2-phase rating not 1-phase, there seems to be some overload on the Y-B pair of the remaining 20Nos welding M/Cs.. Just re-arrange your set up and try to balance the loads.E.g redistribute the 150KVA units to the R and Y lines.

Thanks everyone for thier valuable comments.

Sorry for the belated acknowledgement.

But still I feel that some one should clear my doubt with respect to impact on my power supply quality on account of providing a two phase connection across the primary of a trasformer which has a SCR pack on only one limb for current control