# Three Winding Transformer¶

Model of a three winding transformer. It is assumed, that node A is the node with highest, node B with intermediate and node C with lowest voltage.

The assumed mathematical model is inspired by *ABB Schaltanlagenhanbuch* [Gremmel1999], but with the addition of a
central phase-to-ground admittance, cf. following picture.

## Attributes, Units and Remarks¶

### Type Model¶

All impedances and admittances are given with respect to the higher voltage side.

Attribute | Unit | Remarks |
---|---|---|

uuid | ||

id | Human readable identifier | |

rScA | Ω | Short circuit resistance in branch A |

rScB | Ω | Short circuit resistance in branch B |

rScC | Ω | Short circuit resistance in branch C |

xScA | Ω | Short circuit impedance in branch A |

xScB | Ω | Short circuit impedance in branch B |

xScC | Ω | Short circuit impedance in branch C |

gM | nS | No load conductance |

bM | nS | No load susceptance |

sRatedA | kVA | Rated apparent power of branch A |

sRatedB | kVA | Rated apparent power of branch B |

sRatedC | kVA | Rated apparent power of branch C |

vRatedA | kV | Rated voltage at higher node A |

vRatedB | kV | Rated voltage at higher node B |

vRatedC | kV | Rated voltage at higher node C |

dV | % | Voltage magnitude increase per tap position |

dPhi | ° | Voltage angle increase per tap position |

tapNeutr | Neutral tap position | |

tapMin | Minimum tap position | |

tapMax | Maximum tap position |

### Entity Model¶

Attribute | Unit | Remarks |
---|---|---|

uuid | – | |

id | – | Human readable identifier |

operator | – | |

operationTime | – | Timely restriction of operation |

nodeA | – | Higher voltage node |

nodeB | – | Intermediate voltage node |

nodeC | – | Lowest voltage node |

parallelDevices | – | Amount of parallel devices of same attributes |

type | – | |

tapPos | – | Current position of the tap changer |

autoTap | – | true, if there is a tap regulation apparent and active |

## Caveats¶

Nothing - at least not known. If you found something, please contact us!

[Gremmel1999] | Gremmel, H., Ed., Schaltanlagen. Cornelsen Verlag, 1999, Vol. 10, isbn: 3-464-48235-9. |