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− First letter: relationship of the power distribution system to earth;
" G* Q9 |7 r" F5 T$ wT means direct connection of one pole to earth,
- U6 x! m" X+ a% x: X T, hI means system isolated from earth, or one point connected to earth through an
# `! d( m. m. z% u2 g0 Wimpedance.
4 b8 [7 z$ V/ A& v− Second letter: earthing of the equipment;
4 D( R; b( j* t* [2 }4 eT means direct electrical connection of the equipment to earth, independently of the
: |8 J9 Q6 ^9 O/ W4 \earthing of any point of the power distribution system," L' l+ ? ~' j
N means direct electrical connection of the equipment to the earthed point of the power
7 g( h. E* U6 Bdistribution system (in a.c. systems, the earthed point of the power distribution system, L7 S `% p, n
is normally the neutral point or, if a neutral point is not available, a phase conductor).
4 G6 u3 P F$ z# S% {− Subsequent letters if any: arrangement of neutral and protective conductors;6 b2 K- @0 T, G6 t' L. j- O1 {
S means the protective function is provided by a conductor separate from the neutral or
2 ^: H$ V. w' y' jfrom the earthed line (or in a.c. systems, earthed phase) conductor,
3 [/ j; f0 z, A9 u; g$ f$ E1 AC means the neutral and protective functions are combined in a single conductor
4 _5 i' ^% ~# h9 y(PEN conductor).
: Q" G) r& o, \--`,,`````,,,````,,`,,,``,,,,,`-`-`,,`,,`,`,,`--- |
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