What is the meaning of DYN11 in a transformer?

DYN11 is a notation that describes the vector group of a transformer.

A vector group indicates the configuration and phase angle difference between the primary and secondary windings of a transformer.

The notation consists of four parts:-

The first part is a capital letter that represents the connection type of the high voltage (HV) winding. It can be either Y (star), D (delta), or Z (zigzag).-

The second part is a lowercase letter that represents the connection type of the low voltage (LV) winding. It follows the same convention as the first part.-

The third part is a lowercase letter that indicates whether the neutral point of the star or zigzag winding is brought out (n) or not (o).-

The fourth part is a number from 0 to 11 that represents the phase displacement between the HV and LV windings in terms of clock positions.

For example, 0 means no phase shift, 1 means 30 degrees lagging, 6 means 180 degrees, and 11 means 330 degrees lagging.So, DYN11 means that the transformer has a delta-connected HV winding, a star-connected LV winding with the neutral point brought out, and a phase displacement of 30 degrees lagging. This means that the LV voltage lags behind the HV voltage by 30 degrees in the same phase sequence.

This vector group is commonly used in distribution transformers because it allows for easy grounding of the neutral point and reduces the harmonics and unbalanced currents in the system.