to main earth at a certain point in the power system, normally at
the supplying transformer (T = Terra (Earth)).
||The power system
is insulated from earth or connected to earth through a sufficient
high impedance (I = Isolated).
conductive parts are connected directly to earth e.g. the UPS chassis
disregarding whether the power system is earthed or not.
conductive parts e.g. the UPS chassis are connected directly to earth
at the main earthing point (N = Neutral).
Conductor (PE) and Neutral Conductor (N) are two different and separate
conductors (S = Split).
Conductor (PE) and Neutral Conductor (N) are one common conductor
(PEN) (C = Common).