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用到PWB需在如下几个条件:
7 @, C# d; J! G( p% s6 M+ [' JPollution degree 1:All material groups.
% u2 [1 d5 s0 C1 a" x$ |6 E或者Pollution degree 2:All material groups except IIIb.(即PWB的CTI ≥ 175)5 p/ ~# R" j @* D
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• Insulating material group I CTI ≥ 600;* R- `2 s) N( q7 A4 P: L
• Insulating material group II 600 > CTI ≥ 400;
9 l/ N% @$ |$ ~5 c# @, S• Insulating material group IIIa 400 > CTI ≥ 175;/ @" b( `* {1 _' |6 |
• Insulating material group IIIb 175 > CTI ≥ 100.4 S0 f) n, c! N. l$ b) E* v
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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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