Selection of Transformer Vector Group

does the transformer has tertiary winding?

Ajay,

You indicated that you want one transformer for conversion of 220 kV to 11 kV. After that you want a transformer to convert the 11 kV to another voltage ("big size transformer"). You want to rectify the 11 kV or the output of the big size transformer ?

To avoid trasmitting the 3rd harmonic, a delta connection shall be used, either on the primary of the 220/11 kV transformer (220 kV part) to block them from entering the grid, or on the primary of the big size transformer (11 kV part) to avoid it from entering the 11 kV grid (assuming the rectifiers are on the secondary side of that transformer)

The vector group name shall start with D ( Dxx)

Were do you have a tertiary winding ?

Dear Friends,

I have to buy a transformer of 40 MVA Rating, 220 / 11 kV. This Transformer will be used for for distribution of Total Plant load at 11 kV. This will have various out going feeders for Distribution Transformer of 2 MVA ratings (11 kV / 433 V), 11 kV Motor feeders, Other 11 kV Switch boards installed in other plants & Rectifiers of 14 MVA rating.

For this application if I select 220 kV Trafo with Delta as primary cost will go very high. Hence to reduce transmission of 3rd harmonics on grid, I want to select Delta Winding as tertiary winding in 220 kV Trafo. Means Vector group wil be YNdyn Is this correct?

If yes, then what should be rating & voltage of this tertiary winding?

Regards.

We are having 230/11 kV, 40 MVA transformer..... the Vector group is YnYn0+d11 .. We have a Delta connected Tertiary winding to suppress the Harmonics