Answer / eduardo

In a delta connection you don´t have any access to the "mid
point" or if you prefer to the "neutral".
In a star connection you will have a four(th) terminal, that
you can connect to earth or use it as neutral conductor.
For example if you have a three phase power line at 15 kV,
and want 400 V and 230 V you can connect the primary in
delta (you don´t need the extra connection) and the
secondary at star. (delta- star)
Now you will have 400 V between any 2 phases and 230 V
between one phase and the star point of the transformer.

If you connect the secondary in delta you will not have 230
V, because you don´t have the 4th terminal. (delta-delta)

Please note that in star one winding of the transformer will
have 5,8 kV (10000V / sqrt(3)). In delta connection you will
have in one winding 10 kV. So verify the tension and the
connetction type of the transformer. (both primary and
secondary).

Answer / shahbaz shaikh

in delta-delta transformer primary side and secondary side of transformer are connected in delta fashion i,e R-Y-B are connected in triangle fashion these are generally prefer for the transmission system and here no neutral point is present and for the distribution system we use the delta star because our home appliances are work at 230v but in 3 phase we have 440v so to get the 230v we use delta primary and star secondary so by using one of phase and neutral point of star we can get the 230v.

Answer / atta

Eduardo IS ABSOLUTELY RIGHT ,

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