|
楼主 |
发表于 2013-8-13 23:38
|
显示全部楼层
jsspace 发表于 2013-8-12 16:37 0 J, W/ u9 u2 Q! i) \* t
兄弟,你的理解应该欠妥。# d& h/ V1 K; s
具体应该这样理解:field-wiring branch circuit supply termina 现场安装的 ...
2 B+ U9 V' E8 K1 x" {6 u9 ^2 h. u但根据UL8750 7.8.3 Minimum spacings on printed wiring boards and for board mounted components, between
8 Y6 ?7 w7 Y# b/ h9 Ouninsulated live parts of opposite polarity, between an uninsulated live part and a grounded dead-metal
" C* T8 `/ ?6 e( Z$ q }part, and between an uninsulated live part and an accessible dead-metal part shall be in accordance with
$ I$ u" `- s# m' H, H1 l! o; \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。 |
|