Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new

 Categories >> Engineering >> Electrical Engineering

 Civil Engineering Interview Questions (3151) Mechanical Engineering Interview Questions (3304) Electrical Engineering Interview Questions (13476) Electronics Communications Interview Questions (2395) Chemical Engineering Interview Questions (424) Aeronautical Engineering Interview Questions (77) Bio Engineering Interview Questions (17) Metallurgy Interview Questions (80) Industrial Engineering Interview Questions (166) Instrumentation Interview Questions (2408) Automobile Engineering Interview Questions (111) Mechatronics Engineering Interview Questions (38) Marine Engineering Interview Questions (45) Power Plant Engineering Interview Questions (81) Engineering AllOther Interview Questions (1205)
Question
What is vector group? What is meant by DYN11?Why is it needed?
Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By

# 1
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.

 Is This Answer Correct ? 178 Yes 19 No
Charles

# 2
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)

 Is This Answer Correct ? 120 Yes 28 No
T Eswara Rao

# 3
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

 Is This Answer Correct ? 19 Yes 8 No
Earnest Paul

# 4
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

 Is This Answer Correct ? 23 Yes 19 No
Bikash Chandra Pal

# 5
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
or 11 O'Clock happens before 12O'Clock and the same result is concluded.

 Is This Answer Correct ? 6 Yes 2 No
Ahmed Koriem

# 6
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.

 Is This Answer Correct ? 11 Yes 9 No
Sukhdev Negi

# 7
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

 Is This Answer Correct ? 0 Yes 0 No
Rajiniganth

# 8
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.

 Is This Answer Correct ? 0 Yes 0 No
Fernando Garcia

# 9
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

 Is This Answer Correct ? 2 Yes 7 No
T Eswara Rao

# 10
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.

 Is This Answer Correct ? 2 Yes 9 No

  Question Asked @ Answers Other Electrical Engineering Interview Questions IS THERE ANY ELECTRONIC CIRCUIT TO REDUCE THE NEUTRAL TO EARTH VOLTAGE BELOW 3V ? 1 What is the operating range of voltage and current in grid supply in India? BARC 4 when ELCB breaks the circuit than INVERTER auto-connect the circuit to the battery than how can the operetor is safe?? 1 What is the difference between magnetic loading and electric loading of a machine? 1 What is mean by vector group? For what purposes we doing vector group test in transformers? 2 How many electrones need to flow in one second to equivalent to one Ampere. 3 I want to measure resistance between Neutro and earth conductor for 3 phase Transformer what should i do 1 What are the various methods for effecive earthing in a factory in a rocky terrain, where soil resistivity is extraordinarily high? The usual method of 3 m deep earth pits is not serving the purpose. 4 what is mean by live tank and dead tank in current transformers? 1 what is specific gravity of a battery if specific gravity increase/decrease,what will happen to the voltage/current of the battery NTPC 5 What are the main problems in distribution? I have to do an assignment so which problem should I choose? Like power factor problem etc. 4 I have AC automatic voltage regulator 15KVA What output currant? Siemens 1 For more Electrical Engineering Interview Questions Click Here