132kv cables for transformer feeder, cables in duct at 9029
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5/13/2018 132kv Cables for Transformer Feeder, Cables in Duct at 9029 - slidepdf.com
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CURRENT RETING CALCULATIONS FOR 132KV CABLES AT S/S9029, LAID IN PVC PIPES ENCASED IN CONCRETE
= 9.00E-06 /m
= 3.93E-03
= 900
C= 40
0C
= 550C
= 500C
= 35
0C
= 1.15E-05 /m
=
B:Skin Effect Factor : YS =
= 60 Hz
= 0.435
= 5.71675947
= 32.68133884
= 0.149814702
C: Proximity Effect Factor : YP =
= 0.37
= 4.86385755
= 23.65711027
= 56 mm
= 250 mm= 0.017464778
C: AC Conductor Resistance at maximum operating temperature= 1.33956E-05 /m
D:Dielectric Losses =
= W/m
Wd = CU0tan =
= 2f = 377.1428571
C = *1.0E-9/[18*ln(Di/dc)] =
= Relative Permitivity of Insulation =
A: Conductor DC Resistance at maximum operating temperature
YP = [(XP4)/(192+0.8XP
4)](dC/s)
2[0.312(dC/s)
2+ {1.18/((XP
4/(192+0.8XP
4)+0.27)}]
R = AC Conductor Resistance at maximum operating temperature = R'(1+YS+YP)
Wd = 0, As Dielectric Losses are ignored upto 132kV Rated Cables
YS = XS4/(192 + 0.8XS4)
kP = Proximity Effect Coefficient/Constant
XP2 = 8..f.kP.10
-7/R'
XP4= (XP
2)2
dC = Conductor Diameter
s = Axial Spacing between Cable Conductors (Trefoil Formation in PVC Ducts) .
Air = Temperature difference between & Air (90-55)
R' = DC Conductor Resistance at Maximum Operating Temperature
= R0[1+ ( - 20)]
f = Frequency
kS = Skin Effecet Coefficeint/Constant
XS2
= 8..f.kS.10
-7/R'
XS4
= ( XS2)2
Air = Ambient Air Temperature
Ground = Temperature difference between & Ground(90-40)
R0 = DC Resistance of Conductor at 200C, 1x2000mm2 Cable Size
= Temperature Coefficient for Conductor Material
= Maximum Operating Temperature of Conductor Ground = Ground Ambient Temperature
5/13/2018 132kv Cables for Transformer Feeder, Cables in Duct at 9029 - slidepdf.com
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For unequal lenghts of Minor Sections 1' shall be multiplied by 0.004.
= 0
= 0.033693254
= 1.00E+00
= 115.0167943
= 0.2 mm
= 111.7 mm
= 3.58E-08 -m
== 0.000921324
= 0.024642682
= 0
=
=
=
=
=
=
= 0.078900179
= 0.922572409
= 2.887560604
= 4.988163597=
= 0.000113255 /m
=
=
= 5.22831E-05 /m
F: Thermal Resistances of Cable Parts T1, T
2 & T3 :
T1 = Thermal Resistance between Conductor & Metallic Sheath
T2 = Thermal Resistance between Metallic Sheath & Armour = 0, as thereis no Armour = 0 k.m/W
T3 = Thermal Resistance of Outer Sheath
T1 = (T/2)*ln(1+ (2t/Di))---------- General Formula 0.452432052
of other two, when cables are in flat formation
2 = 0, As there is no Armour in the cable, hence Armour Loss Factor is Zero.
X = 2**10^-7*ln(2*s/d) Reactance of Sheath per unit length of
cable for two adjacent single core cables
Xm = 2**10^-7*ln(2) Mutual Reactance per unit length of cable
between the Sheath of an outer cable and the conductors
m=10-7
/RS , For m 0.1, 1 & 2 can be negleted
F = (4M2N
2+(M+N)
2)/(4(M
2+1)(N
2+1)) , where
M = RS/(X + Xm) &
2= 0
For Outer Cable Leading Phase 0 =1.5(m2/(1+m
2))(d/2s)
2,
1= 4.7m0.7
(d/2s)(0.16m+2)
&
1= (1.14m.2.45
+ 0.33) (d/2s)
(0.92m+1.66)&
N = RS/(X - Xm/3)
2= 21m3.3
(d/2s)(1.4m+5.06)
For Outer Cable Lagging Phase 0 =1.5(m2/(1+m2))(d/2s)2 ,
1= -(0.74(m+2)m0.5
/(2+(m-0.3)2)) &
2= 0.92m3.7
(d/2s)(m+2)
1= (4/107S)
0.5
tS = Sheath Thickness
DS = Externial Diameter of Cable Sheath in mm
S = 1.721*10-8
for Copper, 2.8264*10-8
for Aluminium & 21.4*10-8
for Lead
For Lead Sheathed Cables gS can be taken as unity & (1tS)
4
/12*10
12
can be ignored.For Cable 0 = 3(m
2/(1+m
2))(d/2s)
2,
are not known 1' = 0.03 for direct laied cables & 0.05 for cables in ducts.
1' (For Single Point Bonding it is zero, as no Circulating Currents)
1" Eddy Current Loss is ignored, except for cales having large
Conductor of segmental construction. Hence
1" = (RS/R)*[(gS0(1+1+2)+(1tS)4/12*1012]*F, where,
gS = 1+(tS/DS)1.74
( 1DS10-3
-1.6) ,
For Seath Cross Bonded System, where each Major Section is divided in
to three electrically identical minor sections,1' = 0. Where the lengths of
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