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如果强制要求是PIII的话,一般特殊标准会指出;- Q; R3 h4 z' n; k" _6 Q
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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但是具体还是要看使用环境,见Annex M. 3 G" ~2 R8 y+ e9 r0 l* Y) N. K
– pollution degree 1: no pollution or only dry, non-conductive pollution occurs. The pollution8 D9 K8 S7 s2 S( H6 E& n7 J/ }
has no influence;7 p7 V1 _: v C! |3 D+ l
– pollution degree 2: only non-conductive pollution occurs, except that occasionally a3 F4 J9 s- c m8 W# S2 x
temporary conductivity caused by condensation is to be expected;
3 v3 ^7 f0 c/ N) {) Y– pollution degree 3: conductive pollution occurs or dry non-conductive pollution occurs that; [% T# ~* x0 o9 h! m$ O
becomes conductive due to condensation that is to be expected;1 N( {8 F6 s- E, a- w+ a! d- O+ G
4 W, C8 A2 v: S4 R* jBTW,密封环境才可以判PI |
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