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 [1], but with the addition of a central phasetoground 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 reactance in branch A 
xScB 
Ω 
Short circuit reactance in branch B 
xScC 
Ω 
Short circuit reactance 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 
– 
overall amount of parallel transformers to automatically
construct (e.g. parallelDevices = 2 will build a
total of two transformers using the specified parameters)

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!