Neutral Isolation in Earth Leakage condition

When using the neutral leakage protection relay, the CBCT, i.e current balancing current transformer, which is placed, around all the phases and neutral of the incomer ( Except the earth cable/ earth stripp) will sence the leakahe current as per the below formula and feeds to the earth leakage relay to isolate the circiut, when the leakage current raches the threshold point.

Earht leakage(I) = Vectorail sum of all phases current and Neutral current.

If there is any leakage cuurent occurs from the load side, it will be senced by CBCT and isolate the incoming breaker

My question is the Neutral should be isolated or not in case of earth leakage in TT system? Otherway to ask, is there a dangerous voltage appears in the neutral circuit, when an earth leakage occurs and the RCBO trips. As poer IEEE regulation, the neutral should be isolated in TT system at consumer end. that means, 2 pole RCBO or 4 pole RCBO only to be used. This is to be confirmed with relevant explanation.