MCCB and minimum cable cross-section area based on I5S < If min criteria..

[armin5david]

While preparing cable sizing calculation report for a project , I came across this issue but I havent been able to get a satisfactory solution for it,
For a particular MCCB rating and type as per the "I5s < If min" criteria we calculate the minimum cable size that can be used with the MCCB, where:
If min (3 phase) = 0.95xsqrt(3)xV/sqrt((2R1+R0)^2+sqrt(2X1+X0)^2)
R1,R0,X1,X0 are positive and zero sequence resistance and reactance of cable.

and I5s = Kx Ir
Ir = rated MCCb current
K = multiplying factor from trip curve at 5sec from MCCB current-time curve

the question is in trip curve at 5 sec there is hot and cold trip curve which one should be considered and why?
where can I find the full detail related to this criteria?
Thanks in advance

[pamungkas]

do you mean I^2t < K^2S^2? you can find this criteria in IEC standard. but I never heard I5s < If.