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在4.6.2章节中有如下内容:
0 {& A/ e4 L/ O$ ZCompliance is checked by inspection and measurement. Except for that portion of the side of
' p4 G6 \/ U, }6 V$ E! z$ Qa FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one
8 Z4 W2 L* z* N4 a9 }$ a6 bof the following is considered to satisfy the requirements (other constructions are not
( U: b+ z' a% D; v$ h& rexcluded):: i) R9 X& L0 r+ c, m) Q
− openings that do not exceed 5 mm in any dimension;3 h* d7 E; ~2 }
− openings that do not exceed 1 mm in width regardless of length;
, ?( p0 o. T+ ?% a* h− top openings in which vertical entry is prevented (see Figure 4B for examples);
/ T; P+ S2 |- u+ P9 w2 B$ f− side openings provided with louvres that are shaped to deflect outwards an external% e8 I" T7 J; @' I) s4 B# V
vertically falling object (see Figure 4C for examples);
a* i+ f8 A, M3 {− top or side openings, as shown in Figure 4D, that are not located vertically, or within a: X/ b# L3 z- X# S+ b: ]7 g P
volume V bounded by a 5° vertical projection up to the size of opening L, above bare0 F6 Q, X* n: K0 E7 {) ^6 Q
conductive parts:% H2 }' c0 }: w8 W3 W
• at HAZARDOUS VOLTAGE, or) C! B- X7 P$ e3 u
• that present an energy hazard within the meaning of 2.1.1.5.
- M5 C! \/ i- k5 k( X3 uNOTE 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.
# u( t3 p2 g, u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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