DSH 492 Protection against access to live parts

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广东安规检测
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DSH 492

Protection against access to live parts 1 P+ n1 a0 A' |8 Y3 [7 d

8.1.4

60335-1(ed.3)

Standard: IEC 60335-1:1991, 3rd Ed.
  Z; ~; X$ F6 }2 c+ dSub clause: 8.1.4
- q8 ^7 c/ T& q8 U: s' `5 N3 oSheet No. DSH-492
0 v( @% s8 d9 f- `$ p2 d( ASubject: Protection against access to live parts
; c, P% G. j0 KKey words: - Functional earthing
Decision taken at 40th CTL meeting 2003
Question:
* U2 `- `0 l3 w2 |) l& W9 `  N- LIs functional earthing for the secondary circuit of SELV transformers permitted?
Rationale:
See question.
. ^8 N. u0 Q, L- BDecision:
1) Earthing of secondary circuits of SELV transformers (PELV circuits) is acceptable in
general except when SELV is specifically required by the standard for a specific circuit (for
- f1 i7 @% L* X4 C( q9 ^( lexample in whirlpool baths), in which case earthing of the secondary circuits are acceptable
if:
a) the accessible parts of the secondary circuits are separated from the protective earthing
5 g: Q! V: G/ [7 T" K% a' wcircuit by at least protective impedance, or
b) the accessible parts of the secondary circuits are either directly connected to the protective
earthing circuit or are protected against accidental contact by insulation as specified for Class
III appliances or constructions, in particular the insulation shall be capable of withstanding a
. L" U  K* j+ ]7 [test voltage of 500 V AC for 1 min.
Accessible parts directly connected to the protective earthing circuit shall comply with the
requirements for protective earthing (see sub-clause 27.5) or shall be separated from live
parts of the supply with insulation as specified for Class II construction.
6 K# T' `0 V( o5 W8 b6 o2. See also the following figure.
8 Q3 ^( _: F/ w

: {, X: S0 S- t4 \$ D& _
" {8 A5 F' y* M* q( F7 p! f; Q" I
# [; ^/ p& i1 A+ k& e" W  b