Skin effect coefficient

The skin effect in a single-core cable is substantially the same as the skin effect in a solid round cylindrical conductor having the same d.c. resistance per unit length.

Values are according to IEC 60287-1-1 with extensions from Cigre TB 272. 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

$c_{type}$

Construction of conductor

$d_c$

External diameter of conductor [mm]

$D_c$

External diameter of conductor [m]

$D_{ci}$

Internal diameter of conductor [m]

$d_{ci}$

Internal diameter of conductor [mm]

$D_{encl}$

Outer diameter of enclosure [m]

$k_p$

Proximity effect coefficient

$M_c$

Material of conductor

$M_i$

Material of insulation

$t_{encl}$

Thickness of enclosure [m]

Used in

$x_s$

Factor for skin effect on conductor

Choices

Conductor construction	Conductor material	Insulation material	Copper wire type	Value
3	Cu	PE	unidirectional	0.62
3	Cu	PE	bidirectional	0.8
3	Cu	PE	insulated	0.35
3	Cu	HDPE	unidirectional	0.62
3	Cu	HDPE	bidirectional	0.8
3	Cu	HDPE	insulated	0.35
3	Cu	XLPE	unidirectional	0.62
3	Cu	XLPE	bidirectional	0.8
3	Cu	XLPE	insulated	0.35
3	Cu	XLPEf	unidirectional	0.62
3	Cu	XLPEf	bidirectional	0.8
3	Cu	XLPEf	insulated	0.35
3	Cu	PVC	unidirectional	0.62
3	Cu	PVC	bidirectional	0.8
3	Cu	PVC	insulated	0.35
3	Cu	EPR	unidirectional	0.62
3	Cu	EPR	bidirectional	0.8
3	Cu	EPR	insulated	0.35
3	Cu	IIR	unidirectional	0.62
3	Cu	IIR	bidirectional	0.8
3	Cu	IIR	insulated	0.35
3	Cu	PP	unidirectional	0.62
3	Cu	PP	bidirectional	0.8
3	Cu	PP	insulated	0.35
3	Cu	SiR	unidirectional	0.62
3	Cu	SiR	bidirectional	0.8
3	Cu	SiR	insulated	0.35
3	Cu	PPLP		0.435
3	Cu	Mass		0.435
3	Cu	OilP		0.435
3	Al			0.25
3	Al		4 segments	0.288
3	Al		5 segments	0.195
3	Al		6 segments	0.118
3	Al		7 segments	0.07
3	AL3			0.25