(28) calculate no of plate-pipe earthing & size of earthing strip(10.6.13)

7/27/2019 (28) Calculate No of Plate-Pipe Earthing & Size of Earthing Strip(10.6.13)

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As per IS 3043-1987

Short circuit Current(Isc) 65000 Amp

Duration of Fault in sec (t) 1 Sec

Soil Resisitivity () If You Know (Otherwise Leave Blank) 100 -Mt.Soil Resistivity 100 -Mt.

Permissible Current Density at Earth Electrode (Id) 757 Amp/Sq.Mt

Permissible Earth Resistance of System 2 Detail of Plate Earthing:

Plate Width 600 mm

Plate Height 600 mm

Surface Area of both sides of plate(S) 0.72 Sq.MtMax.Current Dessipated by One Electrode 545.04 Amp

Single Earth Plate Resistance 290.14

No of Copper Plates Earthing Required 119 Nos

Arrangement of Pipe Earthing Parallel 1

Formation of Parallel Earthing (As per BS 7430): Traingle

Distance Betweem successive Electrodes (D) 8 Meter

Overlall Earthing Resistance of 119 Nos of Electrodes 2.467 Whether Earthing Strip / Wire Buried in Ground Yes

Earth Resistance of Buried Strip / Wire:

Strip Width(w): 12 mmStrip Length(L): 2200 Mt

Depth of Burial of Strip Electrode(t): 200 mm

Surface Area of both sides of Strip(S): 52.8 Sq.Mt

Max.Current Dessipated by One Electrode 0.00 Amp

Resistance of Earthing Strip/Wire: 0.1601

No of Plate Earthing 119 NosArrangement of Plate Earthing Parallel

Earthing Strip / Wire For Earthing Buried in Ground Yes

Overlall Resistance of Earthing Plate 2.4666 Resistance of Earthing Strip/Wire 0.1601 Total Earth Resistance of Plate Earthing & Earth Strip 0.1503

:Calculation:

Earthing Strip Size A=(IscXt)/KCurrent Density permissible at an Earth Electrode Id=(7.57*1000)/(xt) Amps/SqmeterNo of Plates required N=Isc/Id/S

Plate R=(/S)*(/S) OhmPipe or Rod R= (100/2L)*log(4L/d)ohmsStip or Conductor R=(100/2L)*log(2L/wt) ohms

Calculate Numer of Plate /

Calculate No of Plate Earthing

Results


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As per IS 3043-1987



Soil Resisitivity () If You Know (Otherwise Leave Blank) 72.44 -Mt.Soil Resistivity 72.44 -Mt.

Permissible Current Density at Earth Electrode (Id) 889.42 Amp/Sq.Mt

Permissible Earth Resistance of System 1 Detail of Pipe Earthing:

Diameter of Pipe(d) 100 mm

Radius of GI Pipe(R.) 0.05 Mt.

length of Pipe(L) 3 Mt.Surface Area(S) 0.943 Sq.Mt


Single Cast Iron Pipe Resistance 18.408

No of Pipe Earthing Required 60 NosArrangement of Pipe Earthing Parallel 1

Formation of Parallel Earthing (As per BS 7430): Hollow Sqare

Distance Betweem successive Electrodes (D) 8 Meter

Overlall Earthing Resistance of 60 Nos of Electrodes 0.514 Whether Earthing Strip / Wire Buried in Ground Yes

Earth Resistance of Buried Strip / Wire:

Strip Width(w): 12 mmStrip Length(L): 2200 Mt

Depth of Burial of Strip Electrode(t): 200 mm

Surface Area of both sides of Strip(S): 52.8 Sq.Mt


Resistance of Earthing Strip/Wire: 0.1160

No of Pipe Earthing 60 NosArrangement of Pipe Earthing Parallel

Earthing Strip / Wire For Earthing Buried in Ground Yes

Overlall Resistance of Earthing Pipe/Rod 0.5135 Resistance of Earthing Strip/Wire 0.1160 Total Earth Resistance of Pipe Earthing & Earth Strip 0.0946

Results

ipe EarthingJignesh.Parmar,

www.electricalnotes.wordpress.com,

[email protected]

Calculate No of Pipe Earthing
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440KV 40 KA for 1 to 3 Sec




11KV(Urban) 35 KA for 1 to 3 Sec

11KV(Rural) 25 KA for 1 to 3 Sec

415V 10 KA for 1 to 3 Sec

220V 6 KA for 1 to 3 Sec

Soil Type Avg. Resistivity (m)Well

graded gravel 600 1000

Poorly graded gravel 1000 2500Clayey gravel 200 400

Silty sand 100 800

Clayey sands 50 200

Silty or clayey sand 30 80

Fine sandy soil 80 300Gravelly clays 20 60Inorganic clays 10 55Surface Soils 1 50

Clay 2

100Sandy clay 100 150

Moist gravel 50 700

Dry gravel 700 1200

Limestone 5 10000

Porous limestone 30 100

Quartz, limestone 100 1000

Sandstone 20 2000

Granites 900 1100

Normal Short Circuit Value

Typical soil resistivity (IEEE 142 / BS 7430)


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As per IS 3043-1987



Copper Aluminium Lead

Volumetric haet capacity of conductor material (Qc) 0.0345 0.025 0.00145

Reciprocal of Tmp.coeff of Resistivity at 0 deg.Centrigade (B) 234.5 228 230

Electrical resisitivity of conductorat 20 deg.Centrigade(20) 0.0001724 0.0002826 0.000214Final Temprature of conductor(t) 395 325 325

Initial Temprature of conductor(i) 40 40 40

Value of k Constant for 1sec 205.60 126.05 34.94

Allowance for Corrosion in Earth Strip 0% Per Year

Number of Year before replacement say 0 Year

Safety Factor 1

No

Earthing Strip Size (Copper): 164.79 Sq.mm 1

Earthing Strip Size (Aluminium): 268.77 Sq.mm 1

Earthing Strip Size (Lead): 969.76 Sq.mm 2

Earthing Strip Size (GI): 419.90 Sq.mm 1

Cable

Short circuit Current(Isc) 33880 Amp XLPE

Duration of Fault in sec (t) 1 Sec PVC

Earthing Conductor Size for XLPE Conductor (Al.) 360.43 Sq.mm

Earthing Conductor Size for XLPE Conductor (Cu.) 235.28 Sq.mm

Earthing Conductor Size for PVC Conductor (Al.) 451.73 Sq.mm

Earthing Conductor Size for PVC Conductor (Cu.) 294.61 Sq.mm

Calculate Minimum Size of Earthing Conductor Value

Calculated Min.Earth Strip Size

Calculate Minimum Size of of Earth Strip


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132KV 35 KA for 1 to 3 SecGI 66KV 25 KA for 1 to 3 Sec

0.0038 J/Cent-mm3 11KV(Urban) 35 KA for 1 to 3 Sec

202 Cent 11KV(Rural) 25 KA for 1 to 3 Sec

0.000138 -mm 415V 10 KA for 1 to 3 Sec500 Cent 220V 6 KA for 1 to 3 Sec

40 Cent

80.69

Width(mm) Thickness(mm) Status

10 20 O.K 164.79 0.00 200

10 30 O.K 268.77 0.00 300

60 10 O.K 969.76 0.00 1200

10 20 Increase No or Size of Strip 419.90 0.00 200

Al. Cu.

94 144

75 115

of k Constant for 1 Sec.

Normal Short Circuit Value

Actual Earth Strip Size

Jignesh.N.Parmar

www.electricalnotes.wordpress.com,

[email protected]
http://www.electricalnotes.wordpress.com/http://www.electricalnotes.wordpress.com/http://www.electricalnotes.wordpress.com/http://www.electricalnotes.wordpress.com/http://www.electricalnotes.wordpress.com/


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Typical soil resistivity (IEEE 142 / BS 7430)

Soil Type Avg. Resistivity (m)Wellgraded gravel 600 1000

Poorly graded gravel 1000 2500Clayey gravel 200 400Silty sand 100 800Clayey sands 50 200Silty or clayey sand 30 80Fine sandy soil 80 300Gravelly clays 20 60Inorganic clays 10 55

Surface Soils 1 50

Clay 2 100

Sandy clay 100 150

Moist gravel 50

700Dry gravel 700 1200

Limestone 5 10000

Porous limestone 30 100

Quartz, limestone 100 1000

Sandstone 20 2000

Granites 900 1100

Concrete 300 500


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(28) calculate no of plate-pipe earthing & size of earthing strip(10.6.13)

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