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有没有人知道如下条款中说提到的电压梯度的峰值如何检测?有没有实例说明怎么将这个条款应用到线路板上呢?谢谢!' ~9 a# s% i3 ]8 G5 e: J
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28.1
; f# w( ?6 o( d8 DFor conductive patterns on printed circuit boards, except at their edges, the values in the
G3 x/ L5 h* q" O2 N# @' g" ?table between parts of different potential may be reduced, as long as the peak value of the
7 A6 r3 \, j5 l$ J7 Bvoltage stress does not exceed:8 f8 \0 F) K6 K- ?; P
– 150 V per mm with a minimum distance of 0,2 mm, if protected against the deposition of dirt;9 N0 \5 z3 J) G# r; r* V- S
– 100 V per mm with a minimum distance of 0,5 mm, if not protected against the deposition of) F$ l1 D$ m! O2 `5 I1 |9 ?6 J
dirt.( j8 B6 i, H4 `
When the limits mentioned above lead to higher values than those of the table, the values of
" q) I$ z# s# X' p9 j; T/ D7 A* Ethe table apply.
# w/ U; n% K; p% x; d/ |For peak voltages exceeding 50 V, the reduced creepage distances only apply if the Proof
0 [. w+ ~; q& `) L+ @Tracking Index (PTI) of the printed circuit board, measured as in Annex G, is greater than
1 ]" R$ y" q2 n175.( H$ m) c9 y- ^- z( ~ R
These distances may be reduced further, provided that the tool complies with the% F- S+ N! D3 U# a) g- C6 a
requirements of Clause 18 when the distances are short-circuited in turn. o$ m+ c/ P7 j$ v: G$ X4 N
6 H( M4 F {3 T1 p对印刷电路板上的导电图形,其边棱除外,只要电压梯度的峰值没有超过下述值,表中关于不同极性部件间的值可以减小. ( g$ L" g$ a9 j" t* z
——若是防尘物沉积的,为150V/mm,但最小距离为0.2mm.
% B* L# z/ x" G* o7 P* Z8 P$ Q' m: Z ——若不是防尘物沉积的,为100V/mm,但最小距离为0.5mm.: y# y' b$ u/ W" T
对峰值电压超过150V的情况,只有印刷电路板的耐漏电起痕指数(PTI)按照附录G进行测量时超过175,减小的爬电距离规定才适用." M& y5 O7 N& q4 ]6 o# w
只要当这些距离轮流短路时,器具符合19章的要求,这些距离可以进一步的减小. |
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