Dyn11

This is the angle between the HV winding and LV winding due to the winding arrangment .The vector equation of phasors yields 30 deg angle =

V L-L = V phase angle <30

Dyn11 - High Voltage winding is Delta connected and Low Voltage winding is Y connected with having neutral terminal.

The last one or two character of the vector group is always numeric. This numeric number multiplied by 30 (11 x 30) designates the degree of angles by which the LV line lags the corresponding HV line. This number (or angle) depends on the arrangement and connection of HV and LV windings within the transformer.

In this case, the phase angle of the LV winding lags the HV by 11x30 = 330 degrees. In other words, the LV winding leads the HV by 360-330 = 30 degrees (either way, it means the same thing).

- MS

Dear all,

A distribution transformer needs a delta winding to reduce the third harmonics, also needs a star winding to create a neutral to earth. Usually the primary (high voltage) side is delta, and secondary (low voltage) side is star for convenience. There is unavoidable 30 degree difference between delta and star side voltages. Dy11 is selected also for convenience. American people prefer Dy1 so that LV voltage always 30 degrees behind the HV voltage.

Regards

i think you are asking why is it 11 instead of another angle.. you see.. for me it depends until your utility's standard or your common practice.

in my country we are using Dyn1..just take note that if you are using Dyn11 all distribution transformers as well as substation transformers should be of the same type for easier paralleling of feeders... i think