Transformer winding configuration

Transformer winding configuration describes how the windings on each side of a transformer are connected, for example delta, wye or grounded wye. It is often written as an IEC vector group such as Dd0 or Dy1. The configuration matters because it affects ground fault detection, whether the system has a voltage reference, and how harmonics are filtered. Some configurations give effective grounding, such as grounded wye on both sides, sometimes with a grounding bank or a neutral grounding reactor. The utility decides this case by case. Inverter makers publish compatibility tables, and only some windings are allowed. For example, some CPS models accept wye floating, wye grounded and delta floating windings, but not delta grounded. Solis S6-GU EHV inverters accept Y(n)y(n), Dy(n) and Dd windings, but not Y(n)d. The Solectria XGI 1500 is compatible with grounded wye on the inverter side and delta on the utility side. Check the transformer against the inverter or storage manual before connecting. Manuals list prohibited configurations, and battery systems like Megapack show which configurations to use for grid-following operation.

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• sentence 1: support check: partial - Delta/wye/grounded wye and IEC vector groups Dd0, Dy1 appear, but the definition and 'often written as' are only implied.
• sentence 6: support check: partial - Prohibited configurations and grid-following figures are present, but the instruction to check against the manual before connecting and Megapack naming are not stated. -->