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在4.6.2章节中有如下内容:
B3 J7 L7 \6 _3 p( e% r6 a6 mCompliance is checked by inspection and measurement. Except for that portion of the side of
# n& t4 V7 M# M& F5 Pa FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one! U9 _7 F( y @
of the following is considered to satisfy the requirements (other constructions are not9 s' ^5 V. C6 h( U% w
excluded):' K$ M6 {$ ~% e0 s8 V
− openings that do not exceed 5 mm in any dimension;4 e0 F% `& D& V
− openings that do not exceed 1 mm in width regardless of length;2 r. l' N% B% x- v! a. K
− top openings in which vertical entry is prevented (see Figure 4B for examples);$ r7 x# t$ C% g9 N' l
− side openings provided with louvres that are shaped to deflect outwards an external
0 V) W0 `# D: u+ F! Tvertically falling object (see Figure 4C for examples);
; m" ]8 g: H" v' g) b− top or side openings, as shown in Figure 4D, that are not located vertically, or within a
U. A. b1 H& N' \& w- \volume V bounded by a 5° vertical projection up to the size of opening L, above bare% I0 U, n, g4 d! ]; h6 U
conductive parts:
, F$ U$ }! G$ V% i8 k9 o• at HAZARDOUS VOLTAGE, or
$ Y# v" }" q" g, P2 S: F8 B+ Z6 r• that present an energy hazard within the meaning of 2.1.1.5. P9 k) t6 X& m. z6 \+ {
NOTE 2 The examples of Figures 4B, 4C, 4D and 4E are not intended to be used as engineering drawings but are only shown to illustrate the intent of these requirements.6 J+ i% e# h( x" h' J& C& P7 U/ t& r
我的个人理解是,顶部开孔除了要满足尺寸要求外,孔下面还要有东西挡着,不能垂直或者5度角投影直接投到危险带电体上。 希望我的看法可以抛砖引玉,可以引来大家更深的讨论。 |
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