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在4.6.2章节中有如下内容:( ?0 N7 k8 C: S: q
Compliance is checked by inspection and measurement. Except for that portion of the side of* V+ C) t2 A% `( }
a FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one
$ R- u3 m( o, P' Yof the following is considered to satisfy the requirements (other constructions are not5 z0 d4 _. b8 r5 b
excluded):7 L% O4 b0 W' X3 u3 h
− openings that do not exceed 5 mm in any dimension;
! g" c# A7 B* ]% m− openings that do not exceed 1 mm in width regardless of length;
2 ^' ~0 g% Z1 \2 z" K4 F− top openings in which vertical entry is prevented (see Figure 4B for examples);
; C. @- B- S- r" R7 B0 Z− side openings provided with louvres that are shaped to deflect outwards an external2 v t5 ^( N4 F, R7 b* ~' B
vertically falling object (see Figure 4C for examples);7 b, t9 g S3 `# u
− top or side openings, as shown in Figure 4D, that are not located vertically, or within a$ K1 b6 \) U O( _
volume V bounded by a 5° vertical projection up to the size of opening L, above bare
9 O. n! p" S d4 ~5 O q( G( Cconductive parts:
- I: ^: k1 T: [9 K. k• at HAZARDOUS VOLTAGE, or* b) Y( g L1 Q
• that present an energy hazard within the meaning of 2.1.1.5.
0 P% L1 C/ D J( t8 w" |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 ?/ q" N/ a& g1 J5 i+ J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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