How are Grounding Impedances Calculated in EasyPower?

EasyPower uses the following formula to calculate Amp Class:

For example, consider a two-winding transformer with a D-Yg configuration as shown below:

The grounding resistance is entered as 20 ohms.

If you choose to enter the Amp Class instead, R+jX is calculated in reverse.

Three-winding transformers use this same calculation.

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