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Question& F3 y* r/ u0 I# S6 Z
1) In case of components mounted on a printed wiring board (PWB) and placed across( \/ u* | t! w! W6 i( m
(bridging) insulating distances on the PWB (e.g. providing basic or even reinforced insulation),
/ g1 q- O9 G4 V; q7 Hhow to deal with the different distance requirements for distances on the printed wiring6 |( M' i" s& F! R6 B9 L
material and for distances on other plastics e.g. the housing material of the component( I! Q4 W) N. M, O+ Y1 `- T) q/ H2 _
(depending on the applicable material group)?
) [! f. t* K& X- V2 l7 X9 W3 C2) In case of components mounted on a printed wiring board (PWB) and placed across
" ^( _9 ]% n+ einsulating distances on the PWB (e.g. providing basic or even reinforced insulation), how to
$ a a8 U! x" ]6 Fdeal with the different distance requirements, if the material group for PWB and for the( U$ |, O, o( G; m
components placed on it is not the same (e.g. PWB of material group I and relay base of
" P; x1 E! b& I; Wmaterial group IIIa)?
1 y2 e0 S6 K& p' tDecision
7 v* F6 U, }9 M8 C/ g1) The defined reduced values for the required creepage distances relevant to printed wiring
. C7 \. U" j/ g+ e4 x8 fmaterial in micro-environment of pollution degrees 1 and 2 may only be applied when there3 E. u; Q T2 U
are no components bridging the investigated insulation. If components are bridging insulating
3 D: N! v6 z' U7 Qdistances on the PWB, the creepage distance requirements relating to the (component)$ C' d8 D% S N5 T. P8 w
material representing the worst case has to be applied for the PWB also.
( \$ P# T" p9 S, ]0 e% c) r2) In case of different material groups for the PWB and the components, again the requirement7 ?7 s' ? f& A, x
relating to the material representing the worst case has to be used.
7 E) I* n( l$ W5 _ zRemark: A component is considered to bridge insulation on the PWB, if the surface of the
' _) h& _ a h; ]component is located at a distance less than the value “X” (e.g. according to IEC 60664 series)+ u# w" O8 c( r7 z A1 g
from the isolating PWB surface. See also enclosed drawing.
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