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Question. ?5 U' R# `% e8 S, P! p
1) In case of components mounted on a printed wiring board (PWB) and placed across
$ F4 d( Y) a4 i4 {. d8 C5 F(bridging) insulating distances on the PWB (e.g. providing basic or even reinforced insulation),; R8 U" G8 k' Y0 Y U3 C" Z, J
how to deal with the different distance requirements for distances on the printed wiring* A. s% ~- h0 K& Q
material and for distances on other plastics e.g. the housing material of the component
5 r2 t4 z1 d' H$ G(depending on the applicable material group)?' C2 c5 c; h% n9 _
2) In case of components mounted on a printed wiring board (PWB) and placed across
+ i( b7 Q1 M9 u& _$ _insulating distances on the PWB (e.g. providing basic or even reinforced insulation), how to
/ ~. k0 n, P: S% adeal with the different distance requirements, if the material group for PWB and for the: g4 N+ _: M# C: p
components placed on it is not the same (e.g. PWB of material group I and relay base of8 ]; \% G3 w7 P" |
material group IIIa)?
$ K, ]; W! i4 U2 }Decision% S ]/ H6 S4 G4 |& ?- B% r! X
1) The defined reduced values for the required creepage distances relevant to printed wiring
2 ]3 k% i8 F; a4 [material in micro-environment of pollution degrees 1 and 2 may only be applied when there) N( R* {& o6 \+ ~: T- a. f( Z
are no components bridging the investigated insulation. If components are bridging insulating
' H: x+ z! T1 A) y# N" r3 |3 |( ], s fdistances on the PWB, the creepage distance requirements relating to the (component)' C8 Y- O, v3 q. ~' T: S
material representing the worst case has to be applied for the PWB also.) K: B4 M; n+ M+ @+ M) \: i# W9 B
2) In case of different material groups for the PWB and the components, again the requirement
4 r/ `2 ~9 a9 o+ @! zrelating to the material representing the worst case has to be used.
# [' i A' C' @, U( TRemark: A component is considered to bridge insulation on the PWB, if the surface of the8 P$ n; m) y+ l, y$ C( M1 f% O
component is located at a distance less than the value “X” (e.g. according to IEC 60664 series)
6 Y* w# i% H/ Gfrom the isolating PWB surface. See also enclosed drawing.+ q1 c! E+ E0 v( d7 T
0 x6 Q* A$ `$ \4 _+ Q
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发表于 2017-1-7 22:05
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