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− First letter: relationship of the power distribution system to earth;+ R1 H3 Z# S {
T means direct connection of one pole to earth,
0 F! X4 f; k2 V" s/ cI means system isolated from earth, or one point connected to earth through an
6 R! {7 k% c5 ^* j: Kimpedance.
- x; Z* y9 R8 `6 G− Second letter: earthing of the equipment;
" H. M4 B$ Z3 Q" S$ ZT means direct electrical connection of the equipment to earth, independently of the, }9 W1 ^; X" S$ U$ d
earthing of any point of the power distribution system,
! ?' i' e; f" e8 f. UN means direct electrical connection of the equipment to the earthed point of the power2 K$ ^- Q" O% ?( p, B( Y% d" I8 K
distribution system (in a.c. systems, the earthed point of the power distribution system
( T, B) N" k( t: _, t: z. [is normally the neutral point or, if a neutral point is not available, a phase conductor).
0 m" u' l& j# ^− Subsequent letters if any: arrangement of neutral and protective conductors;' L3 J0 e: U" D4 v" ~( F
S means the protective function is provided by a conductor separate from the neutral or
1 B- d. }- o" C" a Afrom the earthed line (or in a.c. systems, earthed phase) conductor, V6 H5 Z: V" f' c) ?; x
C means the neutral and protective functions are combined in a single conductor
' b$ ^: z. q) V- r' d(PEN conductor).: k! {1 u3 Y# I6 Z. _' p
--`,,`````,,,````,,`,,,``,,,,,`-`-`,,`,,`,`,,`--- |
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