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woodchips · 23rd Mar 2020, 7:15 pm

Lots of clever people here, try this one.

Need 150V at 25A, as cheaply as possible so not new. Bought some 3ph 400V in to 24V 40A DC out transformers.

Removed rectifiers, split primary into three wye windings similarly the secondary wye windings.

Connect one primary to 230V, get about 12V from the secondary, yes, bit low, not certain why.

Connect two primarys in parallel to increase the flux in the core. But the primary winding on the third leg of the transformer has no, zero, voltage induced in it. Doesn't matter if the energised legs are a centre and outer, or both outers.

This was unexpected, didn't actually consider the problem before powering up, just taken by surprise when prodding around.

Why?

I thought the flux would go along the unused leg, was hoping it would induce a secondary voltage. No secondary voltage, the outer winding, until well into saturation and I think that is radiated induced voltage.

All secondary voltages off load, need to find a large resistor, 1kW.

23rd Mar 2020, 7:15 pm	#1
woodchips Octode Join Date: May 2010 Location: Grantham, Lincolnshire, UK. Posts: 1,176	Three phase transformer Lots of clever people here, try this one. Need 150V at 25A, as cheaply as possible so not new. Bought some 3ph 400V in to 24V 40A DC out transformers. Removed rectifiers, split primary into three wye windings similarly the secondary wye windings. Connect one primary to 230V, get about 12V from the secondary, yes, bit low, not certain why. Connect two primarys in parallel to increase the flux in the core. But the primary winding on the third leg of the transformer has no, zero, voltage induced in it. Doesn't matter if the energised legs are a centre and outer, or both outers. This was unexpected, didn't actually consider the problem before powering up, just taken by surprise when prodding around. Why? I thought the flux would go along the unused leg, was hoping it would induce a secondary voltage. No secondary voltage, the outer winding, until well into saturation and I think that is radiated induced voltage. All secondary voltages off load, need to find a large resistor, 1kW.