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用到PWB需在如下几个条件:1 J/ L6 p( `$ w% {4 h1 v
Pollution degree 1:All material groups.
+ N2 i$ P) ]- {& C% X: U+ m或者Pollution degree 2:All material groups except IIIb.(即PWB的CTI ≥ 175)4 F# x0 W- \3 ?, s" c
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• Insulating material group I CTI ≥ 600;
+ u. u# o( O1 ^8 I• Insulating material group II 600 > CTI ≥ 400;- S$ A; q! P8 r! I; I, \. F E
• Insulating material group IIIa 400 > CTI ≥ 175;; ?) R1 s, @/ ^' X
• Insulating material group IIIb 175 > CTI ≥ 100.* @% v) ]# A* G x) x
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依据以上可以评估是用PWB的绝缘距离还是用Other insulators
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