Vector Group Of Power Transformer

The first letter in the transformer vector group description (in capital notation) implies how the HV winding is connected. For example, 'Y" means STAR and "D" means DELTA. The second letter (in small notation) implies how the LV winding is connected ("y" means star & "d" means delta). If the HV STAR Neutral is brought out, it is denoted by a capital "N" following the capital "Y". Similarly, if the LV star neutral is brought out, it is denoted by a small 'n', following the small 'y'. The following number implies the phase displacement of the LV voltage with respect to the HV voltage, denoted as a clock hour number. Thus, '0' means '0' degrees phase displacement, 6 means 180 degrees phase displacement, 11 means + 30 degrees phase displacement and 1 means - (minus) 30 degrees phase displacement.