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Thickness screen bedding

The screen bedding usually consists of semi-conducting water-blocking swelling tape.

Its thickness is added to the thickness of insulation to sheath $t_1$ which is used to calculate the thermal resistance between conductor and sheath. Therefore it has the same thermal resistivity as the insulation in the calculation. In reality, it usually has a higher value, but the error is small because the layer is thin with typical thickness of less than 0.5 mm.

Symbol
$t_{scb}$
Unit
mm
Used in
$A_{scb}$
Cross-sectional area screen bedding [mm$^2$]
$D_f$
Diameter over filler [mm]
$D_{scb}$
Diameter over screen bedding [mm]
$s_c$
Separation of conductors in a system [mm]
$t_1$
Thickness insulation—sheath [mm]
$t_{1t}$
Thickness insulation—sheath, transient [mm]