ELECTRICAL PARAMETERS OF THE CABLE
• DC resistance of conductor

    The Maximum D.C resistance values of conductors at 20°C are as per IEC 228 standard.
    D.C resistance per unit length of the conductor at other conductor temperature 0 is given by :

   R = Ro [ 1 + α 20 (t - 20°C)]     

where: R = D.C resistance at temperature t ( °C)    Ω/Km

• Inductance

    The Values of the inductance for both multi cores and three single core cables have been calculated based on the     following presumption

 

L = K+0.2 In (2S/d)    mH/km     

where:      K = a constant relating to conductor formation
                 d = Operating Capacitance
• operating capacitance

    The values of operating capacitance for cables have been calculated based on the following presumption.

     C = ε ⁄{ 18 In (D/d)}    μf/km
• Ro = D.C resistance at temperature 20°C Ω/ km (given in the relative tables for each type of cable ).
t = Conductor temperature α20= Temperature coefficient at 20°C 1/°Ct
For copper conductor α20 = 0.00393 For aluminum conductor α20 = 0.00403
• S = axial spacing between conductors for cables in trefoil formation (mm) =1.26 x axial spacing between conductors for cable in flat formation (mm)
The Values for inductance of single core cables have been calculated based on one cable diameter between cables in flat formation.
• Where

ε =Relative permitivity of insulation
D =External diameter of insulation (mm)
d =Conductor diameter (mm)