DSH 717 Creepage and clearance determination, groove, recess, corner, bridging o

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DSH 717

Creepage and clearance determination, groove, recess, corner, bridging of distance X

4.2, 6.2

60664-1(ed.1.2) & 60065-1(ed.2) & All equipment standards based on these 6 h! A3 N- ^+ @

- \& N2 R+ Q" ]* cStandard(s): No. Year
IEC 60664-1/2002 ed1.2
4 N" c: g# r8 B' K0 ]* `IEC 60664-1/2007 ed2.0
All equipment standards
based on these
DSH
4 j2 V2 J7 C, {& a. a0717
2008
Categories:
Various, General
: @% c8 h1 O8 H  f0 Z3 V$ nSubclause(s):
4.2
6.2
+ }( ?3 J& M8 t% dDeveloped by:
WG2 - WG4
Subject:
6 W0 j/ v" d* J0 h' w0 ]$ H- X% ACreepage and clearance
; {7 W  J" _0 c$ Jdetermination, groove,
5 C# \% U. h8 Z9 R7 Lrecess, corner, bridging
/ i8 S9 i- v& }# Iof distance X
& u$ w  B5 y$ C  hKey words:
- Creepage
- Clearance
6 `2 S# c# s! ^; u# I6 o- Groove
- Recess
! Y4 I/ |, ]1 P8 _, h- Corner
: E- L/ `) L' r+ D) \! l& V- Bridging of distance
; U$ h) N/ d. t5 w. u7 W. j) SX
; ?2 Y  p( {0 {3 a% }1 jDecision approved at the
8 m" }/ _+ I' e" R. Q. ]7 \: D3 f5 q2009 CTL Plenary
6 d0 |# j, l+ ~8 y' f. n/ M. X7 UMeeting
  \9 u" T8 W9 X! }, S' X" VQuestions:
- Z5 j4 Q, e' p% x! X1) How shall the examples given in IEC 60664 be interpreted for intermediate situations?
* ]5 e( q" M7 i& b) c1 v5 p9 T0 C2) How shall the example given below be judged correctly, based on the examples given in
IEC 60664-1 and based on the assumption that X = 1 mm?
" V" d5 d" `0 b' J0,8mm
2 mm
6 Y' t' Z5 G, Z4 j% K( E2 i' wPCB
PCB-Track (ending on the
$ H3 |. n/ X% ^; Q) Uedge of the cut-out
3) When shall the sentence:
2 H3 t! ^( y+ a* R“If the associated clearance is less than 3 mm, the minimum dimension X may be reduced to
one third of this clearance.” be applied?
Does this sentence refer to the actual clearance measured or to the minimum clearance
6 a: ~3 P% W& B- _4 ?required?
Decisions:
Ad 1)
An intermediate situation not covered directly by the Standard shall be determined by
considering it as an extension of the most appropriate example from the Standard. An example
of the methodology is given in the Explanatory Notes to Question 2."
Ad 2)
The example shall be judged without any bridging of the corner in the cut-out

creepage = 2,8 mm, no shortcut applicable.
Ad 3)
The sentence shall always be applied whenever the required clearance is less than
  ]% [/ s" v6 P! ^3 mm and the allowed reduction of the minimum dimension X shall be referred to 1/3 of the
required minimum clearance.

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