Modelling an Open Delta (with LV Resistor) Earthing Transformer in ETAP

JezNZ · Aug 8, 2024

Hi All,

For the purposes of Fault Analysis, I'm modelling in etap an 11kV industrial system that until recently had embedded generation.

The system is earthed via a YNd11 12.1kV / 240V open delta transformer with an LV resistor.

I can't find a way to model this in etap directly with the LV resistor on the delta winding, so have converted the resistance into an equivalent primary neutral resistance.

Any thoughts on any problems I may encounter using this method? Transformer nameplate attached for reference.

Thanks

Kayaker11 · Aug 9, 2024

I can't see a problem with modeling the grounding this way. When you run an LG fault as long as your 3IO contribution in the report is correct, everything should be equivalent. Other than putting an arrow on the the ground TCC to indicate fault level, you don't use this value for much in ETAP anyway.

Kiribanda · Aug 10, 2024

ETAP HELP is the best source to get a firm reply on how to model.

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Modelling an Open Delta (with LV Resistor) Earthing Transformer in ETAP

JezNZ

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