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jsspace 发表于 2013-8-12 16:37 2 P0 R, y' ]: n: y
兄弟,你的理解应该欠妥。9 w. c. B" _7 j- W5 y/ |
具体应该这样理解:field-wiring branch circuit supply termina 现场安装的 ... v" E. ~8 U7 F% y
但根据UL8750 7.8.3 Minimum spacings on printed wiring boards and for board mounted components, between9 v3 w3 H- U3 l
uninsulated live parts of opposite polarity, between an uninsulated live part and a grounded dead-metal4 s8 O3 `" }; k7 _- G% }) a1 Q2 S
part, and between an uninsulated live part and an accessible dead-metal part shall be in accordance with
" u! @( I& M; M* QTable 7.4,对于PWB及板上安装的元器件的距离,带电部件到易接触的金属外壳之间,要符合表7.4.那么对于LED驱动,不在PWB板上 带电部件恐怕只有端子连接这类的了,而且这才算合理。如果按照7.6这个表,151-300V内,所有的带电部件到金属外壳的爬电距离需要9.5,不好达到要求。最近有个做UL的案子,灌胶的,277V输入,带电部件到接地端子的距离只有6.5mm,UL 那边都接受。 |
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