We often see transformers in our way almost every day, everywhere. We all might have noticed that there is something written in the transformer like Dny11. But we don't know what does it mean? We can guess that the numbers on the transformer windings show the turns ratio between windings. But by reading this article we might confirm this guess.
The first letter D shows that the primary winding configuration is in delta connection. The second small letter n shows that it has the neutral point and the small y shows that it is star connected. Letter 11 shows the phase difference between the primary and secondary connection according to clock configuration. When the clock hands are between 11 and 12 the angle between them is 30 degrees.
So, Dny11 means
D- Primary winding in delta connection
ny-Secondary winding in star connection with a neutral point
11- There is a phase angle difference of 30 degrees between the primary and secondary line voltages. The secondary line voltage lags by 30 degrees to the primary voltage. Now we know the meaning of each letter.
So in short Dny11 written in a transformer means that has a delta connected primary winding a star connected secondary with the star point brought out and a phase shift of a 30 degree leading 11. It is a 3 phase transformer whose primary side is delta connected and the secondary side is star connected. Here Dny11 is the vector group and the primary side is leading the other side which is the secondary side by a 30-degree angle. This type of power transformer is mainly used in 33/11 kV substations for strengthening the distribution system. Dny11 transformer is widely used in distribution because in the transmission in the power, at some points voltage is stepped up and at some times voltage is stepped down. So to make the system highly efficient, delta winding is used at the l.v side while the star is used.
By this time we have noticed that it is not DNY11 but Dny11. The overall summary is, capital D means the primary side of the transformer is delta connected. Small ny means the secondary side is connected with y with neutral brought out. 11 represents phase shift, which corresponds to 11h in a round clock, a phase is a 30-degree angle which means 330 degrees.
To know more: DNY11 IN TRANSFORMER
Reference:https://en.wikipedia.org/wiki/Transformer
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