I'm after some advice regarding a transformer impedance calculation I need
to produce for a design in the near future; basically the transformer will
be 75kVA with a 400V open-delta primary and single phase 230V secondary.

I am familiar on how to calculate the effective secondary impedance on delta /star and single phase transformers by reflecting the impedance of the primary circuit when the transformers percentage impedance is known; however I'm unsure how to do this with the open-delta transformer described above (as open-delta is non-linear).

I am familiar on how to calculate the effective secondary impedance on delta /star and single phase transformers by reflecting the impedance of the primary circuit when the transformers percentage impedance is known; however I'm unsure how to do this with the open-delta transformer described above (as open-delta is non-linear).