Sorry, I remain unconvinced because of the possibility of thermal equilibrium preventing rupture of the arrester due to low I2t.
In such a case, it is nonsensical to suggest, as you did in post #21, that "protection against over voltage in this case is afforded by MOV's discs connected between each phase and ground"
Mods, don't worry. I'm not going argue the point. It's just too silly to bother with.
Anyway please do not approach and touch any bare ungrounded system wire on the assumption that its voltage is indeterminate!