This function computes the overall inductance of a cable.
When the voltage level is low, the cables have a characteristic reactance per unit length, which is specified at f = 50 Hz. The overall inductance is computed as
L = (XCHA/ω) lCABLE,
where XCHA is the characteristic reactance per unit length, ω = 2 π f is the angular velocity, and lCABLE is the length of the cable.