1) 1st incoming supply on 6kV bus of existing panels is coming from utility (Grid Station) through transformer having vector group of yNyn0+d11 (15/20 MVA Trafo, impedance 7.76/10.35,132kV/6kv).
2) 2nd incoming supply on 6kV bus of existing panels is coming from Generator through transformer having vector group of Dyn11 (5 MVA step up Trafo, impedance 7.5, 400/6kv).
3) 3rd Transformer will be that one which I will propose to client. Please suggest me which VECTOR GROUP should I choose for new Transformer that will be suitable for this system. Dyn-11 or YnYn0 or DD-11 or any other? Please Suggest.
3rd Transformer i.e new Transformer, I am going to propose to my client (11/6kV, 4MVA, Impedance 7.5 % and VECTOR GROUP?)
All three incoming supplies with different above sources will run in parallel on common 6kv bus through synchronization.
Please advice vector group for 3rd Trafo.