# Re: Technical question

#12402

Bhavik said:

Which type of transformer give highest secondary voltage?

1. D/D

2.D/S

3.S/S

4.S/D

Dear ;

If you mean the Voltage value between ” 2 phases “, certainly for the same transformer with ” S : Star connection ” we will have the highest voltage value, for the following reason :

Assume that we have a transformer has on secondary side ” 3 coils ” ( as we have 3 phases ) with ” 231 V ” as the voltage output for each coil, that means we have ” 6 connection points ” that can be connected as follow :

– For ” D : Delta connection ” : we will have as output only ” 3 points ” ( only 3 phases ) where the voltage value between each 2 points is ” 231 V “.

– For ” S : Star connection ” : we will have ” 4 points as output ( 3 phases + neutral ) where we will have ” 2 values ” of voltage output that are :

– ” 231 V between each phase and the neutral

– ” 231 x √¯3 = 400 V ” between each 2 phases.

Noting that :

– For secondary : we can change the connection as we need a Neutral point or not.

– For Primary : we can't do it, because it depends on the supply voltage value.

Regards.