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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!
$ h l, i' r) ?9 D
+ @% G* i8 s+ o/ V, f28.1
3 c/ [2 a% W& t2 [2 KFor conductive patterns on printed circuit boards, except at their edges, the values in the' }+ I3 W/ e1 g- ~
table between parts of different potential may be reduced, as long as the peak value of the
; y8 J- t0 o6 R0 p9 ]8 vvoltage stress does not exceed:
6 v- z: Y1 K8 m! ~– 150 V per mm with a minimum distance of 0,2 mm, if protected against the deposition of dirt;& l6 S) C! e% `$ j# A' l
– 100 V per mm with a minimum distance of 0,5 mm, if not protected against the deposition of2 {+ M( k0 t* s. Q/ O0 m% K
dirt.' B* i; M3 U( s$ }# i/ j! V
When the limits mentioned above lead to higher values than those of the table, the values of( ?4 \1 n/ q- k$ ]
the table apply.
V S1 h a% ^0 ^' M; c0 N' U7 OFor peak voltages exceeding 50 V, the reduced creepage distances only apply if the Proof
1 L! Z2 m1 j/ {" l# `# I# C9 VTracking Index (PTI) of the printed circuit board, measured as in Annex G, is greater than; |0 M7 X5 M0 c+ q Y. m% E
175.2 i, ~* N' r! \( b6 P
These distances may be reduced further, provided that the tool complies with the4 h5 Q# Q+ N$ f" f4 s# b
requirements of Clause 18 when the distances are short-circuited in turn.# m3 O" H M1 D6 | Y
6 |: w1 c" g/ n! [; ~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. 1 M1 o2 J5 j. n9 C$ k
——若是防尘物沉积的,为150V/mm,但最小距离为0.2mm.
5 C: L5 o+ t' ], J5 f( e' H ——若不是防尘物沉积的,为100V/mm,但最小距离为0.5mm.
$ x( x1 P" J4 I 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.7 g% C; o# @. g% L2 r& }" h
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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