JP TECHNOSOFT AHMEDABAD Ph:
7414192 Email:
DOCUMENT : GRID EARTHING
[email protected] CALCULATION RESULT SHEET(IEEE-80)
Date: 01/02/2010
PROJECT :SIEMENS 2
Design ID
R0
Revision No
3Io
=
All nomenclature as per Table-12, IEEE-80, 2000 Symmetrical Earth Fault Current = 40.000 kA
Sf
=
Fault Current Diversion Factor
=
1.0000
Df
=
Fault Current Decrement Factor
=
1.0000
tc
=
Earth Fault Clearing Time
=
1.0000 Sec
V
=
System Voltage
=
132.00 kV
G
=
System Grounding
=
ts
=
Shock Duration
=
0.5000 Sec
M.F.
=
Multiplying Factor For Future
=
1.0000
=
Soil Resistivity
=
40.000 Ohm-Mtr
s
=
Surface Resistivity
=
2500.0 Ohm-Mtr
Lg
=
Grid Length
=
142.00 Mtr
Wg
=
Grid Width
=
74.000 Mtr
h
=
Depth of Burial
=
600.00 mm
hs
=
Surface Thickness
=
100.00 mm
n
=
No. Of Earth Pits
=
20.000
l
=
Depth Of Earth Pit
=
3.0000 Mtr
d
=
Earth Electrode Dia.
=
45.000 mm
Ta
=
Ambient Temperature
=
50.000
INPUT DATA :
MATERIAL DATA DATA : Material =
Shape Of Electrode
STEEL
=
SOLID
o
C
STRIP 20.000
Reference Temp. =
o
C
r
=
Resistivity at 20 Degree C
=
15.000 MicroOhmCm
Tm
=
Max Material Temperature
=
620.00
TJ
=
Type Of Joint
=
WELDED
CA
=
Corrosion Allowance
=
10.000 %
B
=
Volumetric Heat Capacity
=
0.0044 J/C mm
Ko
=
Reciprocal of Temp. Co-efficient of Resistivity at 0 Degree C.
=
218.10
AlphaR
=
Temp. Co-efficient of Resistivity at Ref. Temp.
=
0.0042
SH
=
Specific Heat Capacity
=
0.1140Cal/Grm/C
SW
=
Specific Weight
=
7.8600Grm/cm
AlphaZero
=
Thermal Co-efficient of Resistance at 0 Degree C.
=
0.0065
Page 1/3
o
o
C
3
C
o
3
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JP TECHNOSOFT AHMEDABAD Ph:
7414192
Email:
[email protected] Date: 01/02/2010
DOCUMENT : GRID EARTHING CALCULATION RESULT SHEET(IEEE-80)
PROJECT :SIEMENS 2
Sheet No
R0
Revision No
CALCULATION : IG
= Fault current for Design
=
3Io*Sf*Df
= 40.000 Mtr 2
Asw
= Grid Area
=
Lg * Wg
= 10508 Mtr 2
TCAP
3o = Thermal Capa. per Unit Volume = 4.184*SH*SW = 3.7490 J/cm / C
S
=
Conductor Area Required
1
= IG *
= 454.93 sqmm
TCAP * 10
\ tc*AlphaR*
S
r Actual Area after Corriosion Allowance = Required
Grid Conductor Selected
[
Ko+Tm Ko+Ta
Ln
(37)
]
= 500.42
75 X 10 MM
=
(40)
sqmm
STRIP 36.000 Nos
NL
= Length Wise Cond.
NW
= Width Wise Cond.
Lc
= Conductor Length
LR
= Total Length of ground rod
= 60.000 Mtr
LT
= Total Length of Conductor
= 5854.0 Mtr
LS
= 0.75 Lc + 0.85 LR
= 4396.5
= 19.000 Nos = (NLxWg)+(NWxLg)+Lp
= 5794.0 Mtr
Mt r
FACTORS : km
=
= ks
=
= ki
=
= Kh
Cs
2 D*D (D+2h) h + 16hdeq 8Ddeq 4deq
[(
1 2*PI
Ln
)+ (2n)2/n1\1+h/h
0
]
8 PI(2n-1)
(81)
0.4335
1 PI
[
0.4140
1 2h
+
1 D+h
+
1 D
]
n-2 (1-0.5 )
0.644 + 0.148 n, Where n=na x nb
Ln
4.7189
=
\(1+h/ho)
=
=
1 - 0.09
x
(94)
nc
x
nd
(84-89)
na = 2 Lc/Lp nb = Lp /(4x Asw) \ \ nc = nd = 1.0
(83)
1.2649 (1- / s) ] [ (2*hs+0.09)
(27)
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JP TECHNOSOFT AHMEDABAD Ph:7414192
Email: DOCUMENT : GRID EARTHIN
[email protected] CALCULATION RESULT SHEET(IEEE-80)
Date: 01/02/2010
PROJECT :SIEMENS Sheet No
2
R0
Revision No
RESULT: Conductor Spacing
D =
Grid Conductor Size
=
Grid Resistance
Grid Potential Rise (GPR)
= =
Touch Tolerable Potential Et50 = = Step Tolerable Potential Es50 = = Emd = = Step Potential
75 X 10 MM MM
Rg = (( =
Mesh Potential
4.0000 Mtr
Esd = =
1 1 ( 1 +( ) )+( LT 1+ \ 20LgWg
1 h 1000
0.1791 Ohm
20
)))
LgWg \ (52)
Ig * Rg
7164.6027 Volt (1000 + 1.5 Cs *
s ) * 0.116
(32)
\ ts
591.3675
Volts
(1000+6*Cs * s ) * 0.116 \ ts
1873.3239
(
* Km Km * Ki * IG * 1000) 1000) LM
(
559.1487
Volts (29)
Volts
* Ks Ks * Ki * IG * 1000) 1000) LS
711.0334
(29)
(29)
Volts
Remark: 75x10 STRIP, 20 EARTH PITS
Note :The number in bracket at right indicates Equation NO as as per IEEE80-2000 Page 3/3
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