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在4.6.2章节中有如下内容:
+ u2 ?% v2 e/ t0 H- ^4 Z) XCompliance is checked by inspection and measurement. Except for that portion of the side of9 I- V8 P$ R' G) q0 w
a FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one3 N3 I4 m3 c' M
of the following is considered to satisfy the requirements (other constructions are not1 O. g! U3 C1 x+ w1 {7 ~' Z
excluded):) ?4 g T, n7 \% f4 n" v+ O- }, l& b
− openings that do not exceed 5 mm in any dimension;2 b. M+ _0 Z! _# }" {( H
− openings that do not exceed 1 mm in width regardless of length;
% z6 w, \ U+ C# I/ c− top openings in which vertical entry is prevented (see Figure 4B for examples);% Q* z/ {( r9 x8 F/ G
− side openings provided with louvres that are shaped to deflect outwards an external+ A& A, n; P7 ]4 S7 w' |
vertically falling object (see Figure 4C for examples);
3 H4 {$ Y8 _! z. k" G6 l− top or side openings, as shown in Figure 4D, that are not located vertically, or within a
2 b9 }; j' v) [7 M1 [! x0 Ivolume V bounded by a 5° vertical projection up to the size of opening L, above bare
- C# ]- S& t Z4 K- K+ v! A* w' d$ Uconductive parts:
' H" [' A' ~3 e• at HAZARDOUS VOLTAGE, or
3 t) t9 `% x6 j5 K: j$ A• that present an energy hazard within the meaning of 2.1.1.5.( C# g1 G) ^1 B4 S
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.: [' D, i5 x+ v: p. P) o
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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