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在4.6.2章节中有如下内容:
4 |2 p) x u8 }0 e+ L6 }1 S' HCompliance is checked by inspection and measurement. Except for that portion of the side of
$ t+ l; Q* c8 h, [. o+ |a FIRE ENCLOSURE that is subject to the requirements of 4.6.2 (see above paragraph), any one' J3 e/ M: p, y8 z
of the following is considered to satisfy the requirements (other constructions are not
. V' ~2 I. g. E0 Z+ g1 }& h+ hexcluded):
6 z0 Q" k+ t5 Z' I/ t− openings that do not exceed 5 mm in any dimension;: K6 ^/ ~. t( _ L" {, n" a
− openings that do not exceed 1 mm in width regardless of length;9 u7 ~) R! [% M" O! p% O) q
− top openings in which vertical entry is prevented (see Figure 4B for examples);
/ X* L6 z7 [: F( N. U− side openings provided with louvres that are shaped to deflect outwards an external
+ Y2 Y0 g0 N( {! S. C% Cvertically falling object (see Figure 4C for examples);$ L) k _5 d# ^; _; W
− top or side openings, as shown in Figure 4D, that are not located vertically, or within a, Y! [* Z( f% t: ~0 V* K+ Q
volume V bounded by a 5° vertical projection up to the size of opening L, above bare
. w* N L" ?0 j" Aconductive parts:% l7 j. ^# {/ O6 A
• at HAZARDOUS VOLTAGE, or
( p5 K) W! w7 `7 V• that present an energy hazard within the meaning of 2.1.1.5.
+ G3 g6 k, u: F) v) f" @9 `8 T XNOTE 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. `! q" v. O! K& H; y0 ~
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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