# Skin effect coefficient

Values for cable conductors are according to IEC 60287-1-1. Default value is $k_1$ = 1.0 for cases not covered below.

Values for PP are assumed to be identical to PE and for SiR to EPR.

For hollow conductors, the formula from IEC 60287-1-1 Annex B should be used. This value is also applicable to keystone conductors.

Symbol
$k_s$
Formulae
 $\frac{d_c-d_{ci}}{d_c+d_{ci}} \left(\frac{d_c+2d_{ci}}{d_c+d_{ci}}\right)^2$ Hollow conductor $\frac{D_c-D_{ci}}{D_c+D_{ci}} \left(\frac{D_c+2D_{ci}}{D_c+D_{ci}}\right)^2$ PAC/GIL conductor $\frac{D_{encl}-D_{encl}-2t_{encl}}{D_{encl}+D_{encl}-2t_{encl}} \left(\frac{D_{encl}+2\left(D_{encl}-2t_{encl}\right)}{D_{encl}+D_{encl}-2t_{encl}}\right)^2$ PAC/GIL enclosure
Related
$d_c$
$D_c$
$d_{ci}$
$D_{ci}$
$D_{encl}$
$t_{encl}$
Used in
Choices
Conductor
construction
Conductor
material
Insulation
material
Copper
wire type
Value
3CuPEunidirectional0.62
3CuPEbidirectional0.8
3CuPEinsulated0.35
3CuHDPEunidirectional0.62
3CuHDPEbidirectional0.8
3CuHDPEinsulated0.35
3CuXLPEunidirectional0.62
3CuXLPEbidirectional0.8
3CuXLPEinsulated0.35
3CuXLPEfunidirectional0.62
3CuXLPEfbidirectional0.8
3CuXLPEfinsulated0.35
3CuPVCunidirectional0.62
3CuPVCbidirectional0.8
3CuPVCinsulated0.35
3CuEPRunidirectional0.62
3CuEPRbidirectional0.8
3CuEPRinsulated0.35
3CuIIRunidirectional0.62
3CuIIRbidirectional0.8
3CuIIRinsulated0.35
3CuPPunidirectional0.62
3CuPPbidirectional0.8
3CuPPinsulated0.35
3CuSiRunidirectional0.62
3CuSiRbidirectional0.8
3CuSiRinsulated0.35
3CuPPLP0.435
3CuMass0.435
3CuOilP0.435
3Al0.25
3AL30.25