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Factor for cross-bonded earthing

This is the multiplication factor for cross-bonded earthing.

When the lengths of the three cable sections are not known, $p_{cb}$ should be set to 1, and $q_{cb}$ to 1.2, giving a value for $f_{cb}$ slightly below 0.004.

For two single core cross-bonded cables, which is not covered in the IEC standard, $f_{cb}$ is set to 0.004.

When all the lengths of the three cable sections are identical, $f_{cb}$ becomes zero.

Symbol
$f_{cb}$
Formulae
$\frac{{p_{cb}}^2+{q_{cb}}^2+1-p_{cb}-p_{cb} q_{cb}-q_{cb}}{\left(p_{cb}+q_{cb}+1\right)^2}$three-phase system
$\frac{{p_{cb}}^2+1-p_{cb}}{\left(p_{cb}+1\right)^2}$two-phase system
$0$single-phase system
Related
$a_{S1}$
Length of 1st minor section [p.u.]
$a_{S2}$
Length of 2nd minor section [p.u.]
$a_{S3}$
Length of 3rd minor section [p.u.]
$p_{cb}$
Minor ratio of section lengths
$q_{cb}$
Major ratio of section lengths
Used in
$\lambda_{11}$
Loss factor of shield by circulating currents