Answer / deepak patidar

When the load on the generator becomes unbalanced, negative
phase sequence currents flows. The negative sequence
components produce a rotating magnetic field which rotates
at synchronous speed in a direction opposite to the
direction of rotor field. Hence effectively the relative
speed between the two is double the synchronous speed. Thus
double frequency currents are induced in the rotor. These
currents cause sever heating of the rotor and can cause
damage to the rotor. The unbalanced stator currents also
cause sever vibration and heating of stator. Hence it is
necessary to provide the negative sequence protection to
the generators against the unbalanced load condition.

The negative phase sequence filter alongwith the
overcurrent relay provides the necessary protection against
the unbalanced loads.

Answer / alee xain

We use a negative sequence filter to filter out negative
sequence component, its characteristics are similar to that
of Inverse overcurrent or over voltage relay. we operate
such a relay on the basis of these negative sequence
component of fault current.

Answer / j.venkatesan

In case of the numeric relay the negative phase sequence
current is calculated bu NPS=Ir+a2Iy+aIb.
Where a is an 120 degree phase shift opeator.
This calculated NPS is used for operation of the relay.

Answer / 32r

deeepak patidar the questin is regarding syn. motor so pls make it clear

what is transistors comprised of?

0 Answers  

---

Why need 3phase machine double earthing?

0 Answers  

---

how to calculate the slowness and fastness of energy meter if we have different kw load for example (0.746 kw and meter rev constant 400 and we calculate the 2 rev in 30 sec) please explain the formula thanks

1 Answers   WAPDA Water and Power Development Authority,

---

How transformer winding & oil gets heat.

3 Answers  

---

Can we step up a 230V supply to 400V using a single phase transformer??

2 Answers  

---

For testing 33kv cable hipot testing. How much kv we have to Apply .Give in details.

24 Answers  

---

why we use separate earthing for two seprate machine??

1 Answers  

---

define electrical field?

6 Answers   L&T,

---

what is the breakdown voltage value in BDV test in transformers?

6 Answers   Siva, TATA,

---

how can we detect that which is receiving side and which is sendind end of a trnasmmison line by just seiing it?i.e its which end is coming from genertaing and distribution side?

5 Answers  

---

We have a 1275KVA existing Transformer in a power plant project. Customer want to get it test & confirm whether it is a Dyn1 Transformer or not. Pleae let me know how to test it.

1 Answers   Allied Group,

---

What is the difference between MCB and Earth MCB? What is the working principal of MCB?

2 Answers  

---