Answer / engr. l. o. osuji

Hi questioner,
Earthing T/F or T/Fs are not required in distubution S/S.
For example, here in Nigeria the distribution volage for
the T/F is either 11/0.415kV or 33/0.415kV detla-star.
However, in Transmission S/S where there are 132/33kV star-
delta connected T/F or T/Fs earthing T/F or T/Fs are
necessary. The earthing T/F is connected on the 33kV side
of the main T/F while the star-point of earhing T/F is
connected to ground to provide an artificial star-point for
the main T/F. This so because 33kV distribution ground-
fault current must flow back to the main T/F. Earth fault
protection for the main T/F must sense this current and
isolate the main T/F otherwise the earthing T/F will roast
i.e. burn.

Answer / engr. l. o. osuji

Further to my answer,note that a ground fault at the
distribution S/S must be sensed fast by the relay so as to
trip the disribution cb before the cb for the 132/33kV in
the Transmission S/S is trip by its relay as a back-up.

Answer / deep

in delta connected t/f winding has not neutral point to connect to ground and beacuse LG,LLG fault is sensed by zero sequence current so providing earting on delta side we use earthing t/f.

Please define ampere?

0 Answers  

---

diff.between servo motor and ac motor

0 Answers   Power Grid,

---

we have a rewind motor of 2Hp,2800Rpm, 220Volt AC. how can we choose the running capacitor for this motor, any formula for that?

0 Answers  

---

WHY BREAKER ARE USED IN SUBSTATIONS?

0 Answers   Fedco,

---

motor work in hat principle generator work in what principle transformer work in what principle pls explain with details or answered to ramadoss.sepc@gmail.com

1 Answers   Vestas,

---

what is the formula for calculation of sac?

4 Answers   TCS,

---

how does calculate loss correction factor in transformer

1 Answers  

---

How to calculate percentage impedance of a power transformer.

1 Answers  

---

Shall I use 40A semiconductor Fuses in 32 A SFU ? Frame size is same. What Happen if Fuses burn on SFU?

0 Answers  

---

There is one 40MVA oil cooled transformer (yet to commission), filled with 95% oil and we are trying to fill 5% Nytrogen in that transformer so that there should not be any foreign component inside. But even though there is no leakage, nytrogen is not withstanding inside transformer, within a day or two pressure guage is showing 0. Why is it soooo? Pls reply.

1 Answers  

---

Rules and standards of electrical control wiring ?

0 Answers  

---

WHAT IS THE THUMB RULE FOR DECIDING THE CURRENT RATING OF COPPER WIRES SAY 2.5/4/6/10 MM SQUARE SIZES??

14 Answers   Dubai Group, Saudi Delta Groups, Savitha Electricals,

---