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 9 K1 G- Q# I+ a( S: j5 \, U

4.2, 6.2

60664-1(ed.1.2) & 60065-1(ed.2) & All equipment standards based on these 4 J# b1 I2 L8 C

6 D( y( Z! p2 v. C8 l% \Standard(s): No. Year
IEC 60664-1/2002 ed1.2
( |: A( @; e) W! _2 k5 R: F2 }1 VIEC 60664-1/2007 ed2.0
All equipment standards
% G2 W6 W4 B. _) t" f+ X, D5 Cbased on these
DSH
9 t) Q' c' _* j7 p" j2 n0717
2008
4 d0 M' p* H7 i9 O& D2 MCategories:
- K+ q) ]" D7 ?' L6 G& J7 g% o" ], dVarious, General
Subclause(s):
+ c4 x' t: J1 P9 E4 Y4.2
5 n5 R- q1 @% Q; j# N% a. j3 z6 F6.2
Developed by:
WG2 - WG4
Subject:
Creepage and clearance
determination, groove,
recess, corner, bridging
of distance X
Key words:
- Creepage
) S% G# q4 y3 ~) @+ v+ u- Clearance
# V8 y8 e# |1 H4 o( |- Groove
- Recess
- Corner
- Bridging of distance
X
Decision approved at the
7 ]. x6 E4 @  B- G2009 CTL Plenary
% d/ N: z. W( M% N5 r5 L! sMeeting
! f6 f6 K2 `% t' q2 iQuestions:
1) How shall the examples given in IEC 60664 be interpreted for intermediate situations?
2) 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?
+ }1 f- S# M0 u* D3 ?5 w3 y0,8mm
' ]( H  |; Y& _* k2 mm
PCB
  j- v. j/ x; ~8 a- j! iPCB-Track (ending on the
edge of the cut-out
3) When shall the sentence:
8 O* W) o5 @. t: b- r! p“If the associated clearance is less than 3 mm, the minimum dimension X may be reduced to
+ m4 F8 }# O9 ]- y% g7 Cone third of this clearance.” be applied?
Does this sentence refer to the actual clearance measured or to the minimum clearance
required?
Decisions:
( ~: O& W- O" Q, T2 GAd 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
8 W& {. f! Y9 Mof the methodology is given in the Explanatory Notes to Question 2."
, p7 n: J- d0 cAd 2)
" L( z: I9 @' N# X& IThe example shall be judged without any bridging of the corner in the cut-out

creepage = 2,8 mm, no shortcut applicable.
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5 q# H- G/ J) Z/ V( f( p% M, ^6 L. TThe sentence shall always be applied whenever the required clearance is less than
6 Y: [0 k+ @! |* ~' K* S9 `3 mm and the allowed reduction of the minimum dimension X shall be referred to 1/3 of the
4 ?1 S" ]* m( |1 m, Xrequired minimum clearance.