|
jsspace 发表于 2013-8-12 16:37 7 H) I, v: Q! [: ?. B
兄弟,你的理解应该欠妥。- Q4 u" A4 c# M2 @2 R; Z8 R2 ?
具体应该这样理解:field-wiring branch circuit supply termina 现场安装的 ... 2 n5 g; V& Y6 g5 b: T# d+ q
但根据UL8750 7.8.3 Minimum spacings on printed wiring boards and for board mounted components, between
/ M0 C5 ^+ F: e% u3 z; D$ y7 F, runinsulated live parts of opposite polarity, between an uninsulated live part and a grounded dead-metal1 Q, k( N6 ]/ E+ |
part, and between an uninsulated live part and an accessible dead-metal part shall be in accordance with+ U& k9 U& P: m: j" B/ |
Table 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。 |
|