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

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DSH 717 1 ~& _' v8 w0 d" p

Creepage and clearance determination, groove, recess, corner, bridging of distance X " @7 ~: d( n$ ^4 \& W( Z0 n

4.2, 6.2

60664-1(ed.1.2) & 60065-1(ed.2) & All equipment standards based on these

Standard(s): No. Year
IEC 60664-1/2002 ed1.2
% Q1 X, w3 v( ?; e1 S9 {0 ^IEC 60664-1/2007 ed2.0
* @& t, O) K1 F# d% D% u& I2 dAll equipment standards
) p# B. O/ I1 S, @0 k5 W6 b' G& Bbased on these
( I+ Y6 l. l* s: X' s+ DDSH
/ w- |! k+ }9 a- \- F0717
! K9 `; Q0 u! f% V2008
8 V- O  k+ r. p& ~Categories:
Various, General
Subclause(s):
4.2
3 S% @# c0 }+ F4 L. ^! U# V+ l6.2
  a9 ]0 D- }3 i$ X* VDeveloped by:
9 O& C; d) f' T0 A, A4 H) y' g, DWG2 - WG4
Subject:
; x7 b$ T) V# Y  D3 iCreepage and clearance
. V. i1 x! ~) P/ _" v; W2 Fdetermination, groove,
recess, corner, bridging
3 Q  T+ @8 p- T+ Z0 Lof distance X
+ T# p- u$ X, i- k- @- s$ VKey words:
- Creepage
0 W- z4 j8 x3 ]# A. v- Clearance
- Groove
) ?% Z6 R5 @( r! ]9 @- Recess
5 m! B. b$ Q* n" M! T- Corner
- Bridging of distance
X
+ o+ M( M" t1 F, d/ \Decision approved at the
2009 CTL Plenary
Meeting
6 B$ t2 b+ h- w$ d) v8 U; }( x9 gQuestions:
1) How shall the examples given in IEC 60664 be interpreted for intermediate situations?
5 L3 a9 c' N4 j2) How shall the example given below be judged correctly, based on the examples given in
$ W7 j* i6 F$ K, TIEC 60664-1 and based on the assumption that X = 1 mm?
0,8mm
2 mm
PCB
0 V/ z. e; g( `* L2 d- U! ?PCB-Track (ending on the
edge of the cut-out
3) When shall the sentence:
“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
; f# v( A; k  T1 E$ y9 |required?
; r* d5 p' Q: K! G6 a+ l. nDecisions:
Ad 1)
$ z, ^/ x* C1 h9 W: f) XAn intermediate situation not covered directly by the Standard shall be determined by
* F5 l+ W2 l" v) @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."
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The example shall be judged without any bridging of the corner in the cut-out

creepage = 2,8 mm, no shortcut applicable.
, S; n6 w6 W  [) [Ad 3)
1 O5 q' I. }9 y0 P6 {The sentence shall always be applied whenever the required clearance is less than
& _- Q+ S2 q4 v; f% A3 mm and the allowed reduction of the minimum dimension X shall be referred to 1/3 of the
/ f$ v) p7 F' y9 N6 t. Arequired minimum clearance.
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