132kv cables for transformer feeder, cables in duct at 9029

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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



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

132kv cables for transformer feeder, cables in duct at 9029

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