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如果强制要求是PIII的话,一般特殊标准会指出;
4 S# }' u: C) l如果没有,绝大部分可以判PII,特殊情况,例如有碳刷的串激马达或者直流马达(考虑工作中产生碳粉),有蒸汽通过有有电气部分的内部结构的(部分2件套的水壶),即使特标没要求,也都应该判PIII;
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" U4 }4 a% o6 |1 S, Y8 s- c5 f但是具体还是要看使用环境,见Annex M.
' ~7 ~* o4 k1 `! S/ L! t# J– pollution degree 1: no pollution or only dry, non-conductive pollution occurs. The pollution
, a$ V0 l2 D* L5 i7 E, o+ |has no influence;
/ C2 Q% i4 w7 a/ Z; S– pollution degree 2: only non-conductive pollution occurs, except that occasionally a* D, s1 a! a: z* N! v) B! i
temporary conductivity caused by condensation is to be expected;# R: Z3 r6 R; u- K) ~5 j$ z
– pollution degree 3: conductive pollution occurs or dry non-conductive pollution occurs that
( o3 \5 Y" U0 B. ?4 N% sbecomes conductive due to condensation that is to be expected;
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. t; D+ g" B. M% z J" ]3 G3 @BTW,密封环境才可以判PI |
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