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− First letter: relationship of the power distribution system to earth;
1 ^: ~ H4 w2 i4 u1 HT means direct connection of one pole to earth,. x8 Y4 G% f7 P; ^3 |0 d1 w* `
I means system isolated from earth, or one point connected to earth through an+ l" q5 X7 B/ G; E
impedance.
8 f3 N# _+ d5 F1 h |; y; c/ j− Second letter: earthing of the equipment;
\7 ~2 }; h' m* j( J3 H9 t" W. UT means direct electrical connection of the equipment to earth, independently of the( a& D$ w* |0 y
earthing of any point of the power distribution system,
L4 W) V! V/ J- g( `. ZN means direct electrical connection of the equipment to the earthed point of the power
1 z! }: r+ l) Q5 c" Wdistribution system (in a.c. systems, the earthed point of the power distribution system3 O2 |% N* ^+ J5 ]9 |2 R5 |
is normally the neutral point or, if a neutral point is not available, a phase conductor).# B2 ^, @6 ]) A' b& G# y9 ]7 U
− Subsequent letters if any: arrangement of neutral and protective conductors;
6 P; r# A$ C' ]S means the protective function is provided by a conductor separate from the neutral or
( ?/ E; u) F9 ]- F) \( sfrom the earthed line (or in a.c. systems, earthed phase) conductor,# B7 w# ~. I% p! v; U- L
C means the neutral and protective functions are combined in a single conductor
. ^ a2 Y( ^/ K: i(PEN conductor).
/ s6 ]) ]& g; J2 @--`,,`````,,,````,,`,,,``,,,,,`-`-`,,`,,`,`,,`--- |
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