标题: DSH 168A Resistance to corrosion of current-carrying parts [打印本页] 作者: 小米 时间: 2012-9-5 11:36 标题: DSH 168A Resistance to corrosion of current-carrying parts
Resistance to corrosion of current-carrying parts ! K7 B( R; P3 l3 \
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Generality " ?: ^: ~6 u8 w2 J
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How to judge whether a current-carrying part is resistant to corrosion ?: C+ C0 n+ R/ O# }/ o+ E
Decision:+ T- s& u+ f' L+ p9 J1 \
CEE Recommendation n. 9 “Corrosion of current-carrying parts” may be applied to judge whether a current-carrying part is resistant to corrosion ." Y) s! }& c0 b/ m/ S t7 y
It is quoted in CB Bulletin No. 41 (September 1981). 1 l0 B: f5 O; v5 m# G' b$ Z( ~In the following, for convenience, is reported a part of it: ; S! P& @( O0 x2 ARECOMMENDED TEXT, SCREWS, CURRENT-CARRYING PARTS AND CONNECTIONS.6 y v4 C) H! A. p* t, \1 a$ Z9 v
a) Current-carrying parts and parts of terminals shall be of a metal having, under the conditions occurring in the equipment, adequate mechanical strength and resistance to corrosion. / Y; d+ b6 R! e2 FCompliance is checked by inspection and, if necessary, by measurement and by chemical analysis. 3 H) b2 ?4 ]5 o' H" L! u3 ^0 GAfter all the tests of the relevant specification, the current-carrying parts and parts of terminals shall show no appreciable deformation. 7 |7 V1 v u( B* X: ?+ m1 FExamples of suitable metals, when used within the permissible temperature range and under normal conditions of chemical pollution, are: . [+ t; m/ K3 y( H( k- copper, & c7 I' M& g0 t" k* z9 Q5 t- an alloy containing at least 58% copper for parts that are worked cold or at least 50% copper for other parts,, Z2 s2 \, G" C j+ w/ _7 w! C
- stainless steel containing at least 13% chromium and not more than 0,09% carbon, * H3 X9 j$ C, W- r- Z, o" W: m- steel provided with an electroplated coating of zinc according to ISO Publication 2081-1973, the coating having a thickness of at least:2 D7 P3 y$ E O' l% e' m
* 5 T ISO grade “1 mild” for ordinary equipment,: c) Q7 ]5 l4 w4 u. R
* 12 T ISO grade “2 moderate” for jet-proof and splash-proof equipment, 8 x7 s( n* h- }* 25 T ISO grade “3 severe” for jet-proof and watertight equipment. ; o% M: y) Y/ S3 l2 A; j# N% P- steel provided with an electroplated coating of nickel plus chromium according to ISO Publication 1456-1974, the coating having a thickness at least equal to that specified for:( W4 e- e9 @2 Y* b
* service condition no. 2 for ordinary equipment,/ {% f& Y7 P) r. R. m
* service condition no. 3 for drip-proof and splash-proof equipment, 9 g9 z" C) W! p- Q `/ h* service condition no. 4 for jet-proof and watertight equipment. ) F1 e% G! U) H- Aluminium and its alloys, provided special measures are taken for removing, where necessary, the oxide layer, for obtaining a sufficient and durable contact pressure and for ensuring that the point of connection withstands the corrosion test specified;5 s2 Y4 r2 X- a5 W) F9 h
however, until a suitable corrosion test and an electrical performance test are available, aluminium and its alloys should preferably not be used for current-carrying parts and terminals within the equipment. 2 l4 Y! O2 u0 P1 [! oZinc and other metals which are soft or liable to creep are not considered to be suitable for current-carrying parts and terminals .7 }4 [+ x/ Y$ z
The thickness of the electroplated coatings on steel may be determined by the magnetic method described in ISO Publication 2178-1972, or by microscopical 7 f. G! n0 x& X1 X4 smeasurement described in ISO Publication 1463-1973.6 H% i9 ~9 H$ x P8 ]) {3 |
b) Under moist conditions, metals showing a great difference of electrochemical potential with respect to each other shall not be used in contact with each other . 4 r0 `. w7 i1 | t4 o$ [3 A/ J; N8 vCompliance is checked by inspection.0 z: \, G6 N8 t8 A' I
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DSH 168A