how can we decide where we have to DYn11 or other vector
group transformer
- 4 Answers
- 30475 Views
- BSL, Knight Frank, Security Printing and Minting Corporation of India Limited, I also Faced
- E-Mail Answers
Answer Posted / ramachandran n
Vector Groups are the IEC method of categorizing the
primary and secondary winding configurations of 3-phase
transformers. Windings can be connected as delta, star
(wye), or interconnected-star (zig-zag). Winding polarity
is also important, since reversing the connections across a
set of windings affects the phase-shift between primary and
secondary. Vector groups identify the winding connections
and polarities of the primary and secondary. From a vector
group one can determine the phase-shift between primary and
secondary.
The first criterion to consider in choosing a vector group
for a distribution transformer for a facility is to know
whether you want a delta-star or star-star. Utilities often
prefer star-star transformers, but these require 4-wire
input feeders and 4-wire output feeders (i.e. incoming and
outgoing neutral conductors). For distribution transformers
within a facility, often delta-star are chosen because
these transformers do not require 4-wire input; a 3-wire
primary feeder circuit suffices to supply a 4-wire
secondary circuit. That's because any zero sequence current
required by the secondary to supply earth faults or
unbalanced loads is supplied by the delta primary winding,
and is not required from the upstream power source. The
method of earthing on the secondary is independent of the
primary for delta-star transformers.
The second criterion to consider is what phase-shift you
want between primary and secondary. For example, Dy11 and
Dy5 transformers are both delta-star. If you don't care
about the phase-shift, then either transformer will do the
job. Phase-shift is important when you are paralleling
sources - you want the phase-shifts of the sources to be
identical. If you are paralleling transformers, then you
want them to have the same the same vector group.
If you are replacing a transformer, use the same vector
group for the new transformer, otherwise the existing VTs
and CTs used for protection and metering will not work
properly.
| Is This Answer Correct ? | 40 Yes | 7 No |
Post New Answer View All Answers
What will be the effect if I use inverter as UPS mood?
How is magnetic leakage reduced?
what is the difference between 2 way and 4 pole selector switch???
Explain in details how you would react to an unexpected incident when your supervisor or manager is not around to give instructions?
Assuming that a dedicated neutral earthing transformer is provided for each GT generator, when the two generators are running in parallel, has consideration been given that the earth fault current from one generator stator winding be split between the two neutral earthing transformers? If so, what adverse impact will this have on the operation of the 59N and 27TN devices?
why induction motors are rated at 0.8 power factor.
Why in metering Ct for ammeters ct secondary side is grounded for each Ct but not in case of CBCT (Core balance current transformer)..kindly some1 highlights the reason..is it because net flux is zero?
Why PT voltages are measured with respect to ground? What do u mean by voltage or current polarized.
Dear all i want to know SEWA Electrical Supervisor Licence test Previous Year Questions ? If any body know please send to me zohairaukllah@yahoo.com
give me a clear defination of inductance,and how can u calculate inductance of a motor
what are the sample questions asking to the test cunducting for electrical superwising lisence test?
please give me all the Alarm .Trip ,Safety Relays & Conditions of Chiller mail me on ashokbabunhce@gmail.com
we have one oven for 12 zone we are installed ir lamp in oven we control load from thyrister and 0 to 5vdc so our zone no 8 getting bright in fraction of second so what we do.. Please answer
what is feed back and what are feed back amplifiers?
how do you choose the cable size as per amps rating & the voltage drop for the same.
