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在4.6.2章节中有如下内容:
; |' |$ q0 `0 p' ~' S/ f* cCompliance is checked by inspection and measurement. Except for that portion of the side of
$ M% V; ]" Y5 O. y3 V( U) Sa FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one
& q: q6 F) b+ m& ~of the following is considered to satisfy the requirements (other constructions are not$ M0 H" U2 x b. o3 W4 V, Z+ s
excluded):$ _5 J3 X' p z1 s. m; T
− openings that do not exceed 5 mm in any dimension;
1 f0 Y: e0 c6 V: }5 q$ l− openings that do not exceed 1 mm in width regardless of length;
# g9 H3 b" y8 o− top openings in which vertical entry is prevented (see Figure 4B for examples);
* | ]! I& P, ~− side openings provided with louvres that are shaped to deflect outwards an external, d$ f2 M) x7 b2 v) f, W) A
vertically falling object (see Figure 4C for examples);
5 B9 D. f4 R2 c5 N: a: Q% Z− top or side openings, as shown in Figure 4D, that are not located vertically, or within a
4 l$ t7 [9 H' _: Z) ?8 Z4 R/ xvolume V bounded by a 5° vertical projection up to the size of opening L, above bare( _# ?# ~* G! Y, v. d* C
conductive parts:
0 [. X5 x& _/ F$ F0 N8 n# j• at HAZARDOUS VOLTAGE, or. `, {! q# g5 r4 i8 ] n4 I
• that present an energy hazard within the meaning of 2.1.1.5.& f. t- ]6 i3 N9 i
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.
% G) ?1 `" ^% C1 q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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