Calculate Qty of Chemical Earthing Material & Size of Earthing Rod
June 16, 2023 7 Comments
Calculate Qty of Chemical Earthing and size of Earthing Rod for following specification.
- Earthing Bore Hole (Auger) size is 150MM and Length is 3Meter.
- Chemical Earthing Material is available in Bag of 25Kg.Mixing Ratio of Earthing Compound and Water is 2:1.
- Earthing Rod Material is GI and length is 3 Meter.
- Size of Transformer for Upstream of Electrical Network is 2000KVA,430V,8%Impedance and consider Short Circuit Current is for 0.5Sec.
Calculation:
(A) Calculate Required Chemical Earthing Material
- Volume of Bore Hole = π r² x h
- Volume of Bore Hole = 3.14 x (0.150/2) ² x 3.0
- Volume of Bore Hole = 0.053 m3
- Chemical Earthing in one Bag=25Kg
- Volume of Chemical Earthing material (Dry) in one Bag = Bag weight in kg x 0.00117 m3
- Volume of Chemical Earthing material (Dry) in one Bag = 25 x 0.00117 m3
- Volume of Chemical Earthing material (Dry) in one Bag = 0.02925 m3
- Mixing Ratio of Earthing Compound and Water is 2:1
- Hence Volume of Chemical Earthing material (Wet) in one Bag =0.02925×2 m3
- Volume of Chemical Earthing material (Wet) in one Bag =0.0585 m3
- Required Chemical Earthing material = Volume of Bore Hole x Bag Weight / Volume of Chemical Earthing material (Wet) in one Bag
- Required Chemical Earthing material = 0.053×25 / 0585 Kg
- Required Chemical Earthing material =22.5 Kg
- Required Chemical Earthing material = Volume of Bore Hole / Volume of Chemical Earthing material (Wet) in one Bag
- Required Chemical Earthing material = 0.053 / 0.0585
- Required Chemical Earthing material = 0.9 Bag
(B) Calculate Size of Earthing Rod
- Transformer Full Load Current= Size of Transformer/ 1.732XVolt
- Transformer Full Load Current= 2000×1000 /1.732×430
- Transformer Full Load Current=2685Amp
- Short Circuit Current = Transformer Full Load Current / Transformer Impedance
- Short Circuit Current = 2865 x100 / 8
- Short Circuit Current =33567.86 Amp
- Short Circuit Current =33.6 KA
- Earthing Rod Size= √ (Fault currentx2 x Fault Time) / k
- Where K for GI=80, Aluminium= 126, Copper=205
- Earthing Rod Size=√ (33567.86)2 x 0.5 / 80 (Sq.mm)
- Earthing Rod Size=296.70 Sq.mm
- Earthing Rod Size= π d² / 4 (mm)
- Diameter of Earthing Rod =√ Earthing Rod Size x 4 / 3.14
- Diameter of Earthing Rod =19.4mm
- Length of Earthing Rod=3 Meter
JIGNESH PARMAR
Sir as per IEC, after how many years transformer should be replaced?
How do you calculate earth rod for domestic installation without a private transformer?
Nice design calculation
Thanks sir, Please inform me from where the value of K taken?
Also I have read your panel short circuit calculation there also
I have not found any reference from where the different type of
Value taken.
It should be very helpful if you write down a blog about short circuit
Calculation (50kA fault current) in LT Panel i.e. 3ph4wire 415 volt
short circuit calculation of copper busbar & aluminum busbar.
Great . Thanks
Very useful information. Thanks a lot sir.
Does the the size of earthing electrode guarantee the value of earth resistance in ohms after erection? Does this electrode withstand the short circuit fault current if erected in earth of available soil?