Fault in Delta source to grounded wye- Delta transformer 1

The wye-delta will function as a grounding bank and supply considerable fault current.

The symmetrical fault current will be 1/3 of the available fault current.
Will the asymmetrical fault current also be 1/3 of the conventional fault current or is there another factor making it either more or less than 1/3?

Bill
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"Why not the best?"
Jimmy Carter

The magnitude of fault current will be primarily a function of the wye/delta transformer zero-sequence impedance. For example, if the wye/delta is just a small PT bank the fault current will be very low since the kVA base will be very small. In any case, the wye/delta functions very similar to a zig-zag transformer. In fact, this arrangement can be used to derive a neutral and often includes a resister in the wye neutral to high impedance ground the system.