Answer / charles

Vector group means it define the primary & secondary side
connection type of the transformer says D for the delta
connections & Y for the star connections then the 11 stands
for the phase displacements between the primary side &
secondary side.In the sense in a clock while 11 o clock
shows the angle between the small needle & big needle will
be 30 degree, so the phase displacement will be 30 degree.

Answer / t eswara rao

Vector group of a transformer describes the relation between
primary voltage vectors and the secondary voltage vectors

DYN11 means
D - Primary DELTA connection
Y - Secondary STAR connection
N - Neutral Point available in the secondary star connection
11 - 30 degrees lag (11o clock position for better
understanding)

Answer / earnest paul

It means that the LV winding voltage lags the HV winding
voltage by 30 degrees.
The 11 typically means 11 o'clock on a standard clock.
whenever you see a vector group like Dy11 ar Yd1 or Yd5 ...
all you have to do is first FIX THE HV WINDING AT 12 o clock
now the 11 shows that it is behind 12 on the clock so you
can say that the LV is lagging by....30 degrees
in Yd1, the lv windings is at 1 o' clock meaning it is
ahead of 12 o clock by thirty degrees so it means that the
LV winding leads the HV winding voltage by 30 degrees
in Yd5, the lv windings is at 5 o' clock meaning it is
ahead of 12 o clock by 150 degrees so it means that the LV
winding leads the HV winding voltage by 150 degrees

Answer / bikash chandra pal

Abobe two reply explained correctly "what is vector group".
The answer to the last question "why it is needed" is as
follows:-
By virtue of constrction & terminal connections of the
transformer, a difference between primary vector &
secondery vector occurs. We need to know the same for the
following reasons:-

1)Matching of vector group is required (to avoid
circulating current/ fault ), when 2 transformer need to be
operate parallal on a common bus/system.

2) to provide transformer differential protection correctly.

etc

Answer / ahmed koriem

Simply
the capital letters are for the HV side whether it is the primary or secondary
and the small letters are for the lv side either primary or secondary
Y or y means star
D or d means delta
N or n meas neutral outgoing from the Trans.
11 means that HV side lag lv side by 30° as HV is the reference and lv is at 11 O'Clock and as we know that the positive direction is anti-Clock
wise then lv leads HV
or 11 O'Clock happens before 12O'Clock and the same result is concluded.

Answer / fernando garcia

This is a very controversial topic. I guess many of the
above answers forgot that when it comes to vector groups
the rotation of the Clock is Anti clockwise. First off, you
can never write all the letters in capital letter DYN11.
Always use the Capital to refer to the HV and the lower
case to refer to LV. Secondly, if u have Dyn11 just 11 by
30 degrees i.e. 330 deg. However. 330 deg is equivalent to -
30 deg. ''Cosine of 330=cosine of -30''. Bear in mind that
the HV is always the reference vector, which means HV is
always at 0 deg. So, imagine the Clock is rotating anti
clockwise. You would see that the 11 always comes first
than the 0. The eleven is the LV and the 0 is the HV. In
Conclusion, Dyn11 means that LV leads HV by 30 Degrees
because the displacement among them is -30 degrees.

Answer / sukhdev negi

Abobe two reply explained correctly "what is vector group".
The answer to the last question "why it is needed" is as
follows:-
By virtue of constrction & terminal connections of the
transformer, a phase difference between primary vector &
secondery vector occurs. We need to know the same for the
following reasons:-

1)Matching of vector group is required (to avoid
circulating current/ fault ), when 2 transformer need to be
operate parallal on a common bus/system.

2) to provide transformer differential protection correctly.

Answer / rajiniganth

vector group is the symbol representation of phase
displacement between low voltage winding and high voltage
winding D-delta & Y-star connection which includes the
insulation level of the internal connections also

Answer / t eswara rao

Clarification for shraddha:
11o clock means primari voltage vectors leading 30deg
with reference to secondary voltage vectors.OR secondary
voltage vectors lagging 30deg with reference to primary
voltage vectors.

As in a clock at 11o clock big needle leads small
needle by 30deg OR small needle lags big needle by 30deg

Answer / shraddha

I read a number of answers but nobody has cleared about the
leading and lagging thing. In case of Dyn11, 11 indicates 11
o'clock i.e. a displacement of 30 degrees between HV and LV.
Now in this case, is HV leads LV by 30 degrees or vice
versa and how can one find out that in any of the cases.

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