Factor between a.c. and d.c. resistance of armour

Get the a.c. resistance of magnetic steel armour wire from the d.c. resistance depening on the wire diameter according to IEC 60287-1-1, clause 2.4.2.1

Symbol
$f_{ar}$
Unit
$\Omega$/m
Formulae
$0.1t_{ar}+1$linear extrapolation Cigre TB 880 GP 34
$0.32741\ln\left(t_{ar}\right)+0.97306$logarithmic extrapolation
Related
$t_{ar}$
Used in
$R_{ar}$