CALCULATION OF CROSS SECTIONAL AREA OF HARDWARE WITH RESPECT TO SHORT CIRCUIT LEVEL ASSUMING ADIABATIC THERMODYNAMIC PROCESS Usama Ahmed Transmission Spec ialty Ref: [1] http://www.openelectrical.org/wiki/index.php?title=Adiabatic_Short_Circuit_Temperature_Rise Ref: [1] IEC 60364-5-54 and IEC 60949 I sc_1 50kA := Specified Short circuit Level I sc_2 50kA := Specified Short circuit Level t 1 1s := Specified Short circuit clearing time t 2 1s := Specified Short circuit clearing time ρ d 7.8 10 3 - g mm 3 := Density of Hardware Steel q c 3.8 10 3 - J mm 3 := Volumetric Heat Capcity of Hrdware Steel @ 20 deg C K β 202 := °C Reciprocal of Temperature Coefficent of Resistivity @ 0 deg C c p 0.460548 J g K := Specific Heat Capacity of Hardware Steel θ i 35 := °C Initial Temperature of Hardware Steel Δθ 365K := Permissible Temperature Rise θ f 400 := °C Final Temperature of Hardware Steel ρ 138 10 6 - ohm mm := Resistivity of Hardware Steel @ 20 deg C ρ r 96 10 6 - ohm mm := Resistivity of Hardware Steel Calulated Coefficent of Hardware Material Properties k 1 ρ d c p Δθ ρ r := Calulated Coefficent of Hardware Material Properties k 2 q c β 20 + ( ) ρ ln 1 θ f θ i - β θ i + + := S 1 I sc_1 t 1 k 1 := S 2 I sc_2 t 2 k 2 := S 1 427.833 mm 2 = Calculated Minimum Permissible Cross Sectional Area of Hardware S 2 662.35 mm 2 = Calculated Minimum Permissible Cross Sectional Area of Hardware J 1 I sc_1 S 1 := J 2 I sc_2 S 2 := J 1 116.868 amp mm 2 = J 2 75.489 amp mm 2 = Calulated Maximum Permissible Current Density of Hardware Calulated Maximum Permissible Current Density of Hardware
Substation string hardware short circuit / power arc rating calculation assuming adiabatic thermodynamic heat flow
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CALCULATION OF CROSS SECTIONAL AREA OF HARDWARE WITH RESPECT TO
SHORT CIRCUIT LEVEL ASSUMINGADIABATIC THERMODYNAMIC PROCESSUsama
AhmedTransmissi on SpecialtyRef: [1]
http://www.openelectrical.org/wiki/index.php?title=Adiabatic_Short_Circuit_Temperature_RiseRef:
[1] IEC 60364-5-54 and IEC 60949 Isc_150kA := Specified Short
circuit Level Isc_250kA := Specified Short circuit Levelt11s :=
Specified Short circuit clearing time t21s := Specified Short
circuit clearing timed7.8 103 -gmm3 := Density of Hardware Steel
qc3.8 103 -Jmm3 := Volumetric Heat Capcity of Hrdware Steel @ 20
deg CK 202 := C Reciprocal of Temperature Coefficent of Resistivity
@ 0 deg Ccp0.460548JgK := Specific Heat Capacity of Hardware
Steeli35 := C Initial Temperature of Hardware Steel 365K :=
Permissible Temperature Risef400 := C Final Temperature of Hardware
Steel 138 106 - ohm mm := Resistivity of Hardware Steel @ 20 deg
Cr96 106 - ohm mm := Resistivity of Hardware SteelCalulated
Coefficent of Hardware Material Propertiesk1dcp r:= Calulated
Coefficent of Hardware Material Properties k2qc 20 + ( ) ln 1fi-
i++ :=S1Isc_1t1k1:= S2Isc_2t2k2:=S1427.833 mm2 =Calculated Minimum
Permissible Cross Sectional Areaof HardwareS2662.35 mm2 =
Calculated Minimum Permissible Cross Sectional Areaof
HardwareJ1Isc_1S1:=J2Isc_2S2:=J1116.868ampmm2 =J275.489ampmm2
=Calulated Maximum Permissible Current Densityof HardwareCalulated
Maximum Permissible Current Densityof Hardware
