I have a quick question about three phase transformer windings.

if I have a transformer that is Yd11 but I connect the generator to the d-side instead(primary side). Does it become Dy11 connected or what is the new connection??

Would also appreciate any hints on how to draw the phasor diagram for the new connection.



2 Answers 2


TZDZ is correct that the capitalized letter always stands for the HV winding.

However the letter symbols are always given in descending order of voltage. It is not correct to write dY1 for a Yd11 transformer.

The following citation from IEC 60076.1 (AS 60076.1:2014) should clarify:

7.1 Connection and phase displacement symbols for three-phase transformers and for single phase transformers connected in a three phase bank

7.1.1 Connection symbol

The star, delta, or zigzag connection of a set of phase windings of a three-phase transformer or of windings of the same voltage of single-phase transformers associated in a three-phase bank shall be indicated by the capital letters Y, D or Z for the high-voltage (HV) winding and small letters y, d or z for the intermediate and low-voltage (LV) windings.


Letter symbols for the different windings of a transformer are noted in descending order of rated voltage independently of the intended power flow. The winding connection letter for any intermediate and low-voltage winding is immediately followed by its phase displacement 'clock number' (see 3.10.6).


The capitalized letter stands for the high voltage no matter which side you consider...

The answer you're waiting might be nonetheless dY1 [edited according to comments]


  • \$\begingroup\$ You were apparently wrong, it's supposed to be dY1, it mirrors along the y-axis when you switch sides. \$\endgroup\$
    – George12
    Oct 17, 2014 at 13:35
  • \$\begingroup\$ Hum, you're right, I edited the answer. Funny, that was my original thought, I don't remember what twisted reasonning made me change it ;). \$\endgroup\$
    – TZDZ
    Oct 17, 2014 at 14:10

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