You will need to perform an EMT-type simulation for this purpose. To replicate the fault on the cable insulation, the cable must be explictly divided in two sections at the point where the faulty insulation is present. A switch must be connected afterwards between this point and ground via a predefined fault impedance. The switch is open in normal operation, while a dynamic model controls it by closing one of the phases and shorting it to ground and subsequently opening it. The fault occurence is decided depending on the faulty phase to ground instantaneous voltage (e.g. 0.9 pu treshold). The fault ends (switch is opened) whenever the earth current passes through zero. The sequence repeats whenever the faulty phase voltage goes above the voltage limit. A small example reproducing this behaviour is attached for your reference. Note also the zero sequence compensation reactance installed at the ac voltage source (supply network).