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.

25 kva 3 phase dg how many current will take per phase , plssssssss reply me

3 Answers   Bharti,

---

what is the per unit cost of generation of electricity at thermal,hydro,desael,solar,gas power plant

1 Answers  

---

power inverter we are using 2n3773 power transister in that places we can use any IGBT ?

1 Answers   Essar,

---

Whats the minimum value for I.R. that can be allowed for HT & LT alternators for operation?

1 Answers  

---

explain with the help of loading capability curve,reactive power generation and absorption from synchronous generator?

0 Answers  

---

---

why capacitor is placed in fan

4 Answers  

---

why induction motor takes high current?

1 Answers   Emerson,

---

What is the technical difference between On delay timer and a Star delta timer?

0 Answers   Roche,

---

what is feeder bay?

0 Answers  

---

What is a advantage of Self Reset Lockout ? On Fault breaker get trip & fault no longer exist then self reset lockout how inform us?

0 Answers   Bhad Engineers,

---

What are the different types of testing in ht cables?

3 Answers  

---

how the capacitance is caluclated if the load is varying to keep the power factor constant(above0.95)

1 Answers  

---