Answer / thiru

transformer differential protection does not operate when
there is out zone fault.because that time two sides of CT's
sense same current. there is no difference of current.so
the relay does not operate.

Answer / v.selvakumar

through fault or external fault it won't operate.

Answer / zahid ali

Turn to turn fault it won't operate.
in other case if the neutral is grounded grounded through
high impedance or Resisted earth fault it wouldn't be
operate on ground fault.

Answer / zahid ali

because there is no difference in the current at the ends
of a winding with shorted turn: a turn fault would have to
burn through major insulation to ground or another phase
before it could be detected

Answer / minu

not the ground fault, if its settings are kept low enough,
it will operate for ground fault also. i am looking for
some other answer.

Answer / siddharth tayade

onely internal fault is detected by the diffrential relay
it will not trip under through fault condition

Answer / zahid ali

Ground Fault

Answer / minu

no. i am asking abt the in-zone faults only. for what in-
zone faults or some conditions will it not operate.

Answer / minu

hi zahid, thanks for the reply. can u pl elaborate a bit on
why it wont operate on turn to turn faults or for other
cases that u mentioned.

Answer / minu

does that mean that a shorted turn fualt wont be detected
by any other relay too???

Simultaneous trip of incoming and outgoing breakers of 400kv/220kv trnasformer. What are the probable causes?

2 Answers  

the minimum clearance b/w ceiling and plane of leaf of ceilng fan shall be ..........mm

1 Answers  

In Megger which types of test we can do ? and How it works? How to use?

3 Answers   Power Grid,

Why cannot we insulate HT over head cable to avoid ionization of air around the HT Cable?..By this we can minimise corona loss also..

1 Answers  

When testing an earthing connection, we use a 60 or 100 candle bulb with a phase connected direct from supply and the other wire to the new earthing provided.If the bulb glows then the earth is ok.Else earth connection is not Ok. So, why dont we can use all the home appliances taking a single wire from the phase and the return connection to Earth instead of return connection to neutral?

2 Answers  

Why celling fan rotates in anticlockwise direction and table fan in clockwise direction ? Give technical reason.

5 Answers  

How to take the Vector Group Test in Transformer? What is the purpose of doing Vector Group Test?

3 Answers  

Give me the calculation steps to design an electromagnet to be work in 230V 50 Hz AC Supply. Also give force that is created by that electromagnet when it gets energized.

0 Answers   GE,

at present how many EHVAC lines are there in India?

8 Answers   HCL, L&T,

EHV current carrying parts need to have smooth finish,then how can a 245kv GIS with emery finish can run so long?

0 Answers  

What is clock position of Transformer?what are the clock positions are there?and what is different of them?

0 Answers   Synergy,

Alternator couple to diesel engine why, Alternator couple to ac service motor with gear drive for 1500 rpm possible (yes or no) aim to low input power supply give to motor then high output power taken for alternator Please answer this question

1 Answers   Turbo,