Answer / mrutyunjay mohanty

Dear Sir,

Greetings of the day !

Recently I have been through one answer shared by you and got your email id at AllInterview.com. Please kindly help me in my below concern :

Permissible current density equation i = (7.57*1000) / sqrt(resistivity * duration of earth fault)

Answer / mrutyunjay

Dear Sudhakar Sir,

Greetings of the day !

Recently I have been through one answer shared by you and got your email id at AllInterview.com. Please kindly help me in my below concern :

Permissible current density equation i = (7.57*1000) / sqrt(resistivity * duration of earth fault) as per IS 3043

Is this equation to be taken for all types of electrodes ( Plate, Rod or Pipe & Strip ) ?

Because , as per IS 3043, same equation is appropriate for plate electrode

Answer / sudhakar.g

The earth resistance of single rod or pipe electrode is calculated as per IS 3040:
R=100xρ/2×3.14xL (loge(4xL/d))
Where:
ρ = Resistivity of soil (Ω meter),
L = Length of electrode (cm),
D = Diameter of electrode (cm)

Example:
Calculate number of CI earthing pipe of 100mm diameter, 3 meter length. System has fault current 50KA for 1 sec and soil resistivity is 72.44 Ω-Meters.
Current Density At The Surface of Earth Electrode (As per IS 3043):
• Max. allowable current density I = 7.57×1000/(√ρxt) A/m2
• Max. allowable current density = 7.57×1000/(√72.44X1) = 889.419 A/m2
• Surface area of one 100mm dia. 3 meter Pipe = 2 x 3.14 x r x L = 2 x 3.14 x 0.05 x3 = 0.942 m2
• Max. current dissipated by one Earthing Pipe = Current Density x Surface area of electrode
• Max. current dissipated by one earthing pipe = 889.419x 0.942 = 837.83 A say 838 Amps
• Number of earthing pipe required = Fault Current / Max.current dissipated by one earthing pipe.
• Number of earthing pipe required = 50000/838 = 59.66 Say 60 No’s.
• Total number of earthing pipe required = 60 No’s.
• Resistance of earthing pipe (isolated) R = 100xρ/2×3.14xLx(loge (4XL/d))
• Resistance of earthing pipe (isolated) R = 100×72.44 /2×3.14x300x(loge (4X300/10)) = 7.99 Ω/Pipe
• Overall resistance of 60 no of earthing pipe = 7.99/60 = 0.133 Ω.


If you have any doubt regarding this ...pls mail me sudhakar28485@gmail.com

how the speed decreases of a generator in power station if load increases

1 Answers   Tata Power,

---

which is chemical used as in ro water what is difference betweeen multi grade filter&dual media filter

1 Answers   Dalkia,

---

what is the dedicated earthing

1 Answers   Reddy Labs,

---

why we use ac?why we use dc? why we we cannot use only ac/dc for all the applications?what happen if we use?

0 Answers  

---

draw the full wave and half wave circuit of 3 phase system and inverter circuit used in ups 

1 Answers  

---

i have dry type transformers can you help me that how many tests i can do to know the performence of transformer and also please tell me about the BDV test and Insulation resistance test in oil cooled transformers

4 Answers   Hyundai,

---

how to calculate unit consumption on 3phase 380-415 v0lt kilowatt motor eg ( 55kw,380v,3phase 50-60hz)

1 Answers  

---

HOW TO CALCULATE BATTERY BACKUP TIME & AH CAPACITY AGAINST UPS KVA RATING?

2 Answers  

---

When the relative speed between the magnetic fields of stator and rotor does is zero under steady state operation?

1 Answers   HPCL,

---

HOW TO CALCULATE AMPs OF CURRENT TRANSFORMER IN HT Panel

1 Answers   MAB,

---

can we use IGBT as a AC-DC converting device in the applications?

2 Answers  

---

What is the normal earth resistance?

11 Answers  

---