Answer / chandan tripathy

As per IS 3043, Cross Section Area of Earthing Conductor
(A) =(If x√t) / K
Where:
t = Fault current Time (Second).
K = Material Constant.
Example: Calculate Cross Section Area of GI Earthing Conductor for System has 50KA Fault Current for 1 second. Corrosion will be 1.0 % Per Year and No of Year for Replacement is 20 Years.
Cross Section Area of Earthing Conductor (A) =(If x√t) / K
Here:
If = 50000 Amp
T = 1 Second
K = 80 (Material Constant, For GI=80, copper K=205, Aluminium K=126).
• Cross Section Area of Earthing Conductor (A) = (50000×1)/80
• Cross Section Area of GI Earthing Conductor (A) = 625 Sq.mm
• Allowance for Corrosion = 1.0 % Per Year & Number of Year before replacement say = 20 Years
• Total allowance = 20 x 1.0% = 20%
• Safety factor = 1.5
• Required Earthing Conductor size = Cross sectional area x Total allowance x Safety factor
• Required Earthing Conductor size = 1125 Sq.mm say 1200 Sq.mm
• Hence, Considered 1Nox12x100 mm GI Strip or 2Nox6 x 100 mm GI Strips

Answer / bala.a

you will follow as per State electricity board norms - 50
x 6 mm Cu for Nu and 50 x 6 mm GI FOR body 0r
you will calculate as per short circuit calculation
Formula 0.0054 x root t x I
Where
t =1 second
I = SHORT CIRCUIT CURRENT
example
Fault current- 33kA( assumed )
0.0054 x root 1 x 33000= 178.2 mm
so you will recommended 50 x 4 mm Cu

Answer / k.prakashchandra

For above 750 KVA ,earth lead is determined as per I.S.1886

Answer / nitin

Mr. Bala,
what is 0.0054factor? Is it root3 divided by current rating
in A/sq.mm? Then for Cu it is 205 A/sq.mm and so root 3
divided by 205 comes to 0.0084. OK?

how to find number of run for transformer & alternator secondary side? give the example.

2 Answers   Powergear, Regen Powertech,

---

when ELCB breaks the circuit than INVERTER auto-connect the circuit to the battery than how can the operetor is safe??

1 Answers  

---

what is the voltage regulation constant of ACSR Raccoon conductor

1 Answers   KSEB, PSC,

---

Can double compression glands be used with regular cables?

0 Answers  

---

what is the difference between ac and electric

1 Answers  

---

I have a 1000 kVA Transformer(11kV/0.415kV) and a APFC panel of 400 kVAR(LT).Now if i want to remove the LT APFC panel and install a HT(11kV) APFC panel on the HT side is the HT APFC panel will work same as the LT APFC panel(improve the power factor),if yes what will be rating of the HT APFC panel?what is the formula to calculate HT APFC panel rating???

2 Answers  

---

circuit diagram of trip circuit supervision relay

0 Answers  

---

how to identify conection leads of an unknown electric motor

0 Answers  

---

What is the power ratio between power in Star and Delta circuit?

3 Answers  

---

what is power factor

3 Answers  

---

What is I to C?

0 Answers   PowerTech,

---

which is batter in construction job,ELCB or RCCB?

7 Answers   HCC,

---