## I2t Thermal Withstand

The thermal withstand of a cable can be determined by comparing the maximum energy at the fault, with the maximum energy the cable can absorb.  The equation for this is:

${I}^{2}t\le {k}^{2}{A}^{2}$

I2t is proportional to the energy let-through of the protective device
I - fault current, A
t - fault duration, S

k2A2 is proportional to the energy withstand of the cable