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− First letter: relationship of the power distribution system to earth;
. l4 a3 |) z2 n6 ~4 | QT means direct connection of one pole to earth,# G; {" i$ M$ p( ~9 B, O0 D6 Y7 S$ q' f; J
I means system isolated from earth, or one point connected to earth through an
5 P5 l) c+ ^, g3 n) Rimpedance.
2 h, e5 [+ ~: N' O# g' Y− Second letter: earthing of the equipment;5 t d2 ~. D, j; v4 v5 [1 }
T means direct electrical connection of the equipment to earth, independently of the
8 P O0 k8 |+ Jearthing of any point of the power distribution system,7 w+ Y6 N: E. W& ?: \7 a+ ~+ b! Z% I
N means direct electrical connection of the equipment to the earthed point of the power
: G6 n5 V$ x, ?. ]( H3 Rdistribution system (in a.c. systems, the earthed point of the power distribution system
8 c' ~, E4 [! Qis normally the neutral point or, if a neutral point is not available, a phase conductor).$ _- _, d, U! g- B
− Subsequent letters if any: arrangement of neutral and protective conductors;
: u" q: j s! pS means the protective function is provided by a conductor separate from the neutral or
$ M4 s& C9 D! [from the earthed line (or in a.c. systems, earthed phase) conductor,$ {- S$ V4 E/ J% A0 ?5 ^+ z, h
C means the neutral and protective functions are combined in a single conductor
; f6 v& U$ v8 j$ k) O(PEN conductor).
R% L, f) `/ d--`,,`````,,,````,,`,,,``,,,,,`-`-`,,`,,`,`,,`--- |
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