Three Winding Transformer / SLG Fault on High Side

[saladhawks]

I am seeking clarification about the zero sequence network connection for the following three-winding transformer:

High: Wye-Grounded (connected to utility source)
Nominal KVA: 16000
Rated Voltage: 34400

Medium: Wye-Grounded
Nominal KVA: 16000
Rated Voltage: 17200

Low: Delta
Nominal KVA: 2400
Rated Voltage: 2400

For a SLG fault on the bus directly upstream of the High side of this transformer, my understanding is that the ground fault current is affected by the parallel connection of the utility and transformer High-to-Low zero sequence networks. My hand calculation for this SLG fault is not agreeing with the results produced by SKM PowerTools. Is the parallel connection between the utility and transformer different than I am assuming?

Thanks in advance.

 

[magoo2]

The zero sequence will have a high-to-tertiary value that will contribute ground fault. Since the ground fault is on the high side of this transformer, the high-to-low impedance won't have any effect.