Answer / jagadisha

The vector group is used to know the type of winding in
Transformer.First letter in the vector group indicates
primary winding(neutral is indicated if present) and the
second letter indicate secondary winding and next letter is
indicate phase difference between primary and secondary..
let us consider vector group Dyn11-It is most coomon 3-PH
connection,ie Delta is on primary and Star on sec with phase
displacement of 30deg

Answer / bijay

well things are explained well above.
i wud like to add something
WHAT WILL BE EFFECT WHEN PHASE DISPLACEMENT CHANGES IN
TRANSFORMER ?
Ans:-First thing under an abnormal condition(during fault)
the neutral point of trafo rised above the ground potential
and attains a positive potential,hence a current will flow
through the trafo neutral to the ground (mostly the trafo
neutral is earthed with or without a NGR.
As a whole the bottom line is trafo neutral will rise to a
potential which is not desired,protection against the same
is designed,which cut of the supply it this condition
prevails for a longer time( this time is descided at the
time of designing the system.

Answer / sunil ulange hit nidasoshi

Vector Groups are made especially to make out difference in
the connections. The connection can be delta(D) or star(Y)

The primary winding connection always denoted by Capital
Letter (D), and secondary winding connection always denoted
as small letter (y), and neutral n

The number after that indicates the phase difference
between the primary and the secondary voltage.

e.g.-> DYn11 means transformer is star connected with
secondary voltage leading the delta connected primary
voltage by 30 degrees.

normally distribution transformers are have Dyn11 connection
because secondary of transformer are connected to at user
end means motors,inductive load etc,

These loads always havelagging Power factor thatswhy Dyn11
connected transformer means secondary volatage leads by
primry voltage by 30 degrees, hence Power factor maintened
constant.

In Clock 11 indicates angle between 12 & 11 is 30 degrees
i.e. 360/12=30 degree

Sunil ulange
Application Engineer
Southern power equpment Limited bangalore

any Questions @ sunil_031@yahoo.com

Answer / poonam

Vector Groups are made especially to make out difference in
the connections. The connection can be delta(D) or star(Y)
The number after that indicates the phase difference
between the primary and the secondary voltage.
e.g.-> Y11 means transformer is star connected with
secondary voltage leading the primary voltage by 30 degrees.
I am not sure of the effect of phase displacement in
transformer

Answer / geno peter

well , significance of vector group depends upon the load
of the transformer. if phase displacement changes then the
connections in the transformer or tap switch of the
transformer has some problems

Is the inductance parameter of transmission line affected by taking the earth into consideration?is the same true for capacitance? Justify the answer.

1 Answers  

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Dear Sir, we met a disaster with our 62.5 kva genset, after rewinding we informed by our contract engg that due to return current coming in neutral & impropper earthing this happend. But after all set up & load balance we checked & found again we have about 20 to 32 amp return current on neutral. we have 12 airconditioner + 12 mini fridge on single phase line. Pl suggest any idea to solved this problem

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