Answer / abhinav yadava

Earthed System
 Earlier the generators and transformers were of
small capacities and hence the fault current was less. The
star point was solidly grounded. This is called earthed
system.

Unearthed System
 Today generators of 500MVA capacities are used
and therefore the fault level has increased. In case of an
earth fault, heavy current flows into the fault and this
lead to damage of generators and transformers. To reduce
the fault current, the star point is connected to earth
through a resistance. If an earth fault occurs on one
phase, the voltage of the faulty phase with respect to
earth appears across the resistance. Therefore, the voltage
of the other two healthy phases with respect to earth rises
by 1.7 times. If the insulation of these phases is not
designed for these increased voltages, they may develop
earth fault. This is called unearthed system.

in a delta-star with neutral grounding on star side what will happen if one star limb  got opened at star point

1 Answers   NTPC,

---

will 1050kva DG set withstand for back charge of 16MVA transformer

0 Answers  

---

What will hapen if we connect more capacitors than required for powerfactor control? Exactly what will be the effect on power system?

2 Answers   Mandovi Pellets,

---

For high voltage and low current Circuit Breaker preferred is vacuum circuit breaker.why?

1 Answers  

---

difference b/w semiconductor and insulator

5 Answers  

---

how capacitor active and reactive.

1 Answers   Birla,

---

What are the applications of the electric motors?

0 Answers  

---

what's the activities of reactor in Buchholz relay?

1 Answers   Yahoo,

---

What types of testing in 11Kv Ht switchgeat during testing?

3 Answers   TCE,

---

How cable from Kit-Kat to main switch, from starter to motor are designed?

0 Answers  

---

what is the difference between b c d curves on mcb

0 Answers  

---

why buchholz relay installed in inclined position

3 Answers   Eskom,

---