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

Discussion in 'Programming/Internet' started by Sean, Oct 8, 2018.

1. ### SeanGuest

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?