# Equivalent circuit to use when calculating the impedance of an electrical cable from its...

Discussion in 'Physics' started by Sean, Oct 8, 2018.

1. I'm trying to work out the impedance of a cable (specifically a single twisted pair of Lapp Kabel 0035836). The datasheet quotes the following information:

Mutual capacitance:
C/C: approx. 120 nF/km
C/S: approx. 160 nF/km

Inductivity:
Approx. 0.50 mH/km

Can I assume the equivalent circuit is something like this: simulate this circuit – Schematic created using CircuitLab

and can I assume the impedance follows the following equation? $$Z_{total} = Z_{R} + Z_{L} + Z_{C}$$

where

$$Z_{R} = R$$ is the resistance (calculated using the resistivity of copper, the conductor material); $$Z_{L} = i \omega L$$ is the "inductivity" above multiplied by the length; $$Z_{C} = \frac{1}{i \omega C}$$ is the "C/C" value which I assume is the "core to core" capacitance, multiplied by the length.

Is my logic correct, or have I misinterpreted the datasheet parameters and/or the equivalent circuit to use?