(28) Size of Earthing Strip _ Wire (1.8.23).xlsx

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2	Calculate Minimum Size of Earthing Strip													Jignesh.Parmar, www.electricalnotes.wordpress.com, jiguparmar@yahoo.com
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4	Location		Short Circuit Ciurrent (Isc) KA	Duration of Fault (Sec)	% of Corrosion in strip per Year	No of Year for Replacement of Strip	Safety Factor	Size of Earthing Strip (Sq.mm)				Actual Size of Earthing Strip (Sq.mm)				Results
5	From	To	Short Circuit Ciurrent (Isc) KA	Duration of Fault (Sec)	% of Corrosion in strip per Year	No of Year for Replacement of Strip	Safety Factor	Copper	Alluminium	Lead	GI	Material	No	Width (mm)	Thickness (mm)	Results
6			10 KA	1	1%	1	1	49	80	289	125	GI	2	6 mm	50 mm	O.K	600	125
7			10 KA	1	1%	1	1	49	80	289	125	GI	2	6 mm	50 mm	O.K	600	125
8								0	0	0	0						0	0
9								0	0	0	0						0	0
10								0	0	0	0						0	0
11								0	0	0	0						0	0
12								0	0	0	0						0	0
13								0	0	0	0						0	0
14								0	0	0	0						0	0
15								0	0	0	0						0	0
16								0	0	0	0						0	0
17								0	0	0	0						0	0
18								0	0	0	0						0	0
19								0	0	0	0						0	0
20								0	0	0	0						0	0
21								0	0	0	0						0	0
22								0	0	0	0						0	0
23								0	0	0	0						0	0
24								0	0	0	0						0	0
25								0	0	0	0						0	0
26								0	0	0	0						0	0
27								0	0	0	0						0	0
28								0	0	0	0						0	0
29								0	0	0	0						0	0
30								0	0	0	0						0	0
31								0	0	0	0						0	0
32								0	0	0	0						0	0
33								0	0	0	0						0	0
34								0	0	0	0						0	0
35								0	0	0	0						0	0
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40					Copper	Alluminium	Lead	GI
41	Volumetric haet capacity of conductor material (Qc)				0.0345	0.025	0.00145	0.0038
42	Reciprocal of Tmp.coeff of Resistivity at 0 deg.Centrigade (B)				234.5	228	230	202
43	Electrical resisitivity of conductorat 20 deg.Centrigade(∂20)				0.0001724	0.00028264	0.000214	0.000138
44	Final Temprature of conductor(øt)				395	325	325	500
45	Initial Temprature of conductor(øi)				40	40	40	40
46	Value of k Constant for 1sec				205.60	126.05	34.94	80.69
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49	Normal Short Circuit Value		Typical soil resistivity (IEEE 142 / BS 7430)
50	440KV	40 KA for 1 to 3 Sec	Soil Type		Avg. Resistivity (Ω‐m)
51	220KV	40 KA for 1 to 3 Sec	Well‐graded gravel		600 – 1000
52	132KV	35 KA for 1 to 3 Sec	Poorly graded gravel		1000 – 2500
53	66KV	25 KA for 1 to 3 Sec	Clayey gravel		200 – 400
54	11KV(Urban)	35 KA for 1 to 3 Sec	Silty sand		100 – 800
55	11KV(Rural)	25 KA for 1 to 3 Sec	Clayey sands		50 – 200
56	415V	10 KA for 1 to 3 Sec	Silty or clayey sand		30 – 80
57	220V	6 KA for 1 to 3 Sec	Fine sandy soil		80 – 300
58			Gravelly clays		20 – 60
59			Inorganic clays		10 – 55
60			Surface Soils		1 ‐ 50
61			Clay		2 ‐ 100
62			Sandy clay		100 ‐ 150
63			Moist gravel		50 ‐ 700
64			Dry gravel		700 ‐ 1200
65			Limestone		5 ‐ 10000
66			Porous limestone		30 ‐ 100
67			Quartz, limestone		100 ‐ 1000
68			Sandstone		20 ‐ 2000
69			Granites		900 ‐ 1100
70			Concrete		300 ‐ 500
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83						Copper
84						Alluminium
85						Lead
86						GI
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