there is a DB board fed from a centre tapped transformer only on single pole breakers. The board feeds instrumentation. Is there any issue changing it to 110v and tie the neutral to earth there is no socket outlets fed on this so can’t see it as an issue?
is there enough oomph! in the circuit to take out a MCB if there is a dead short?
If you're only interested in protecting the cables, then In <= Iz should achieve that - even if it takes minutes or hours to disconnect.
For shock protection it might be more interesting - but if all else fails then you can always throw an RCD into the mix.
You're quite right to think about the magnitude of the fault current - not only do you have the 110V circuit and transformer impedance to worry about, but the fault current will also be limited by the 230V side L-N impedance - which might not be insignificant in some situations.
is there enough oomph! in the circuit to take out a MCB if there is a dead short?
If you're only interested in protecting the cables, then In <= Iz should achieve that - even if it takes minutes or hours to disconnect.
For shock protection it might be more interesting - but if all else fails then you can always throw an RCD into the mix.
You're quite right to think about the magnitude of the fault current - not only do you have the 110V circuit and transformer impedance to worry about, but the fault current will also be limited by the 230V side L-N impedance - which might not be insignificant in some situations.
