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本帖最后由 piratedu 于 2013-10-15 13:59 编辑
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/ i/ W7 T3 X. B4 Y A: Z1 t我有个问题想请教下各位大神,在看IEC61800-5-1时,标准中对protective bonding的测试给出了两种方法: Q; P. l, i5 P0 P7 R' q
& v7 d9 F+ z. \+ H" B' E9 a方法一在bongding横截面积满足要求的前提下通过测关注点到接地间的电阻来判断;) t; N* C$ p5 A2 {: t6 ~! `
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方法二是通过测量bonding两端的电压来判断,但标准中未给出under fault conditions下的具体fault conditions的定义及测试方法。1 ~: F0 D+ j( D* j2 X* j6 P
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想请教各位,你们在遇到该问题时是如何考虑的,谢谢。* K$ _0 Y: c: n- \( y% p. g
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附 标准内容:
8 g/ n3 G+ e& A2 U0 F3 y" x; `4.3.5.3.2 Rating of protective bonding
7 s0 C( c$ }. F8 }( O6 d9 pProtective bonding shall withstand the highest thermal and dynamic stresses that can occur to the PDS/CDM/BDM item(s) concerned when they are subjected to a fault connecting to accessible conductive parts.
7 z" J& B' B* \6 ?& e; F, WThe protective bonding shall remain effective for as long as a fault to the accessible conductive parts persists or until an upstream protective device removes power from the part.
8 ~& }! ^! A) Q4 v) }NOTE In cases where the protective bonding is routed through conductors of low cross-section (for example, PWB5 B; Q% Y) z6 b8 N4 ?
tracks), particular care should be taken to ensure that no undetected damage to the bonding circuit can occur in the) j) b; g+ _$ J1 d
event of a fault.
" x/ e o* o8 `5 L% b' CThese conditions will be satisfied if the cross-section of the protective bonding conductor is the same as that for the protective earthing conductor according to 4.3.5.4. For testing, see 5.2.3.9.
; P R# D1 ~9 R7 P% q- N; u- ^Alternatively, protective bonding may be designed to meet the impedance requirements of 4.3.5.3.3.
W" `, |' f1 j4 c. @# P4.3.5.3.3 Protective bonding impedance0 Z: f8 U! t8 R H" v
The impedance of the protective bonding shall be sufficiently low that:& l. S: P- H" B0 w- d
• during normal operation, no voltage exceeding continuously 5 V a.c. or 12 V d.c. can persist between the accessible conductive parts and the means of connection for the protective earthing conductor,
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• under fault conditions, no voltage exceeding AC-2 or DC-2 in Figure 7 can persist between accessible conductive parts and the means of connection for the protective earthing conductor until an upstream protective device removes power from the part. The upstream protective device considered for this requirement shall have the characteristics required by the installation manual according to 6.3.7.
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