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Convection factor (Heinhold)

Coefficient for convection to air for one single cable, three cables spaced and three cables trefoil are given in the book 'Kabel und Leitungen für Starkstrom' by L. Heinhold, 5th edition 1999. The book does not give values for 2 cables. It was assumed that the values are identical to 3 cables.

Symbol
$k_{sa}$
Related
$inst_t$
Installation in air inside a room
Used in
$\alpha_{sa}$
Heat transfer coefficient for convection [W/(K.m$^2$)]
$T_{sa}$
Thermal resistance by convection, surface to air [K.m/W]
Choices
IdValueInstallationRemark
11.01 cable
21.03 cables spacedequal for horizontal and vertical spacing
30.8333 cables touchingequal for horizontal and vertical spacing
40.6673 cables touching trefoil