Answer / madhu

the neutral grounding transformer is star connected on the
primary and has an open delta on it's secondary.Open Delta
has two terminals.A resistor is conected across these two
terminals. whenever a fault occurs, an emf will be induced
in the open delta and there will be a voltage drop in the
resistor connected. this voltage drop will be sensed by the
potential transformer connected across this resistor. at
the secondary of the potential transformer we have the
neutral displacement relay which will give a trip signal or
an alarm whenever its settings exceed a particular value.

Answer / m.babu

By giving these two wires to Neutral displacement relay.
in the event of earth fault condition some voltage appears
across the relay and it will trips the circuit breaker.
In healthy condition '0' volts across the relay.

Answer / gunasekaran

at balance condition voltage appear across the open delta
connection is zero at fault candition no longer zero.
so we r using this open delta connection for resudial over
voltage protection.

Answer / k.prakashchandra

This relay is used for stator earth fault protection for
generators.The vector sum of three phases in all corners of
delta connected PT secondaries is zero.One of the corners is
taken through a voltage relay.Operation is as above.

Can I use cable armour as a earth conductor? if not how many GI/CU wires I need to run along with cable?

1 Answers  

---

how we can measure the dc current instead of clamp meter ?

1 Answers  

---

What will hapen if we run generator below 47.6hz frequency?

9 Answers   TATA,

---

How to synchronization will be done between two DGs ?

0 Answers  

---

what is the difference between switchgear and circuit breakers and is there any difference between outdoor and indoor switchgear and circuit breakers , and how would you differentiate between switch yard and substation and grid station . thanks

0 Answers   ABC,

---

How can we findout the maximum efficiancy of Transformer? At which load?

0 Answers   HAL, Tanfac,

---

For Eg a 30 kw motor at full load how much kw it takes And at no load how much KW it will take?

1 Answers   GEPL,

---

what is the meaning of the HT LT transformer?

10 Answers   Sify,

---

-What shall be short circuit current of LV switchgear for a 1000 kva, 11.415kv, 3 phase tranformer with 5% reactance.

0 Answers  

---

What is class ab operation?

0 Answers  

---

I have done my m.tech in electrical engg discipline. Can any one please suggest me how should I prepare for getting into phd in iit or nit.How should I prepare for getting into lecturership

0 Answers  

---

why the tapping of transformer on ht side??????

12 Answers   CTS, OPTCL, Visa Steel,

---