What is the difference when selecting a cable between AC
and DC current?

Answer Posted / hdk

For DC, current distribution is uniform in all over cross section of cable so electrical cross-section = physical cross-section.

For AC, current distribution is non uniform due to the time varying nature of magnetic flux produces. So that Electrical Cross-section < physical cross-section. So Rdc<Rac.

So for AC to to transmit same current as of DC we need too select a cable which has more cross-section area than DC.
Rac=K×Rdc, where K=nearly 1.2

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