it depends how many settings you have - some MCCB have an I2t setting as well as a simple time setting- which is closer to an adiabatic case. if as in the example below you can alter the amplitude and time delay of the Isd, then you can play the game where you allow a large overload for a short time or a modest overload for a long time, Ultimately the things to consider are co-ordination with other protection, usually downstream, but perhaps upstream as well, and yes at the higher longer settings the cable mass and thermal inertia come into it as well but factors like not blowing the incomer and not false tripping on events that downstream distro should have caught instead are more often the dominant factors.

Mike

Long time (Ir) and short (Isd) time protection. Example : In = 2000 Amps. Set the long time dial to 0.7 and multiply by 2000 gives you 1400 Amp (long time) set (Isd) to 3. (3) multiplied by 1400 Amps gives you a (Isd) of 4200 Amps. So now Co-ordination/selectively with other protective devices needs to be studied. And max impedance values can be calculated and verify disconnection times are met.