Vector Group of Transformer Dyn1|Dyn11|Ynd1|Ynd11
The naming convention popularly known as Vector Group of Transformer was established by the International Electrotechnical Commission (IEC) through IEC 60076-1. This was done in order to create a notation for three-phase transformer winding configuration.
Vector Group of Transformer: Common Symbol Designation
Y or y – star winding
D or d – delta winding
N or n – neutral
0 to 12 – phase displacement in terms of clock position in multiples of 30° (see figure 2)
According to the standard, the notation should follow HV-LV-Phase displacement sequence with the HV winding in uppercase and LV winding in lowercase.
Consider for example a winding configuration shown in figure 4. As shown, the HV winding is connected in delta while the LV winding is connected in wye. This configuration belongs to the vector group of transformer Dyn1 where the LV lags the HV by 30°.
The Delta Connection
Study the Delta Connection and you’re on your way to mastering the most common Transformer Vector Groups!
Notice how the HV winding is connected in figure 4. The delta connection shown is that of a DAB where the polarity of phase winding A is connected to the non-polarity of phase winding B. The DAB connection is characterized by line currents leading the phase currents by 30°. The other delta connection is the DAC where the polarity of phase winding A is connected to the non-polarity of phase winding C. The DAC connection is characterized by line currents lagging the phase currents by 30°. Knowing the type of delta connection is very helpful in understanding the vector groups Dyn1, Dyn11, YNd1, and YNd11. A Dyn11 for example indicates that the LV leads the HV by 30°, therefore the HV winding should be DAC connected.
Can you determine the vector group of the configuration shown in figure 1? Share your answer in the comments section below.
References
G. Pradeep Kumar, “Principles of Transformer Protection”, proceedings of Power System Protection Training, Visayan Electric Company, Cebu City, Philippines, December 2016.
Hi, i was wondering can you paralell dyn11 and ynd1 transformers?
This is very informative and easy to understand and i just learnt something please can you help with connection of CT’s and PT’s considering their rations and substation
dear sir my question is: what would be the resultant phase voltage and current of two Dyn1 transformers connected in series, 34.5/4.16kV & 4.16/0.48kV?.
please explain this with drawing if possible. thank you for your cooperation.
Hello, thanks for the write up. Please what is the difference between Dyn1 and Dyn11 and their different advantages
Hi, thank you for your interest in the topic. About your question, the difference between Dyn1 and Dyn11 is the relationship between the primary and secondary currents. For Dyn1, the secondary current, wye side, LAGS the delta side by 30 degrees whereas for a Dyn11, its the opposite, secondary currents, wye side, now LEAD the delta side by 30 degrees. There is actually no particular advantage or disadvantage between these but two.
There you have it. I hope we’ve answered your query.
Would the difference between using Dyn11 or Dyn1 allow for power factor correction? or compensation? I’ve been involved with a couple solar field jobs and all the transformers are Dy11 or YNy5 configurations. This would explain their use of odd transformers, or they just are different in general.
Hi,
We have looked this up in research gate and based on one of the answers,
Hossein Mahdinia Roudsari
Iran University of Science and Technology
“It is the nature of delta and star connections and there is no specific intention to use this vector group. The secondary side of a distribution transformer must be yn or zn to provide the neutral connection, and usually the primary side connection is Delta to avoid 3’rd harmonics to inject to the network and improve the balanced conditions…”
He also mentioned that Dyn connection can exhibit 1, 5, and 11 clocks.
Hope this helps. Cheers!
No, because power factor is phase displacement between voltage and current, whereas phase shift created by a transformer will equally shift current and voltage waveforms. Generally we try to limit the phase shift where the connection point is to the supplier network because phase shift affects transient stability. This is especially true for hybrid systems where switching transients are present between generating sources.
Dyn1 means LV winding is leading by 30 deg to Hv winding
Dyn11 means LV winding is lagging by 3o deg to HV winding.
i totally agree with you
I am trying to do transformer protection using 387e , I am little confused when its referenced uprestrained element should be set at 10 pu , pu of what ? which winding tap , lets say I am using two winding , w1 high side winding with the tap1 , and winding 2 with tap 2 , when it says 10 pu of which tap base ? is it tap2-tap1 base ( operate current ) , or is it tap1+tap2/2 , i am thinking operate because 87u should respond to the value of iop , please get back to me asap on that one
Hi Sharad,
The values you set in SEL-387E are in multiples of TAP. This means that for a specific transformer, say, for example a 33MVA, 69/23kV transformer with current transformer ratio of 80 and 240 for the high and low side, respectively. In SEL-387E, you have the option to calculate the TAP setting manually or you can have the relay automatically compute that for you. To calculate the TAP setting manually, you can check these links.
Compensating CT Ratio Mismatch | Differential Protection
Transformer Differential Protection: Application Example
In the example I just presented, you will get a TAP1 and TAP2 setting of 3.45. What this means is that, if you have a U87P of 10, that is about 34.5A secondary or 2760A (34.5×80) primary in the high side which also translates to 8280A (34.5×240) primary in the low side.
I hope I have answered your question.
Regards,
PAC Basics
YNd11 – based on the given diagram of Figure 1 (can’t figure it out from the single line).
Q1: How to know the vector group by looking at the single line only w/o the diagram?
Q2: What are the effects of vector group to a) power circuit , b) protection circuit?
Thank you for your interest on the topic. To answer your questions, first let us refer to figure 1. We’ll focus our attention to the delta connected side. From the figure, you will notice that the polarity of winding A is connected to the non-polarity of winding B (refer to the square dots on the symbol). This forms a DAB connection wherein line currents lead the phase currents by 30. With the wye side as the reference vector at 12 o’clock, we can draw the delta side vector at 11 o’clock. Based from this, we can say that this transformer connection belongs to the vector group Ynd11.
For Q1, there is no way to determine the vector group on a one-line diagram except when explicitly labled. Most standard drawings include the vector group by the way.
For Q2, transformer vector group is very important especially when your system will eventually be connected another system in parallel at any point. With regards to the protection circuit, you will need the vector group information in order to decide how you will wire the current transformers or if you are using numerical relays, what compensation will you need to apply. If you want read about vector group application on differential protection, you may want to read this.Wiring Current Transformers for Differential Protection
I hope this clears things out. Stay curious and keep learning!
This is very informative and easy to understand.
Kudos to author Engr. Luciano Mercado, Jr.
More power and knowledge sharing!
‘really appreciate your comment here. Thank you!
welcom what is the different between vector symbols ZN and vector group Yniii ?