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 ( R0 T) p# u% E, t2 A8 ]

Standard(s): No. Year
7 A; k$ V4 }6 U$ l- P4 @4 pIEC 60664-1/2002 ed1.2
/ o3 W( W( F4 ]# j6 E0 ]IEC 60664-1/2007 ed2.0
& S( |$ q. u- Q# H) _8 n! WAll equipment standards
, A2 [9 o) ]/ X! ^3 _based on these
DSH
8 p! X1 p: V0 o0717
5 k) Q7 n. d- z. f# N( ?# b: ^8 }2008
Categories:
Various, General
: Z+ U( X4 M8 [Subclause(s):
4.2
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Developed by:
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Subject:
Creepage and clearance
determination, groove,
recess, corner, bridging
2 W# Q$ k& G, f3 |- L$ jof distance X
Key words:
- Creepage
9 R5 v% [6 r8 |9 M- Clearance
3 a7 m- M8 r/ R- n; X% A& w9 l- Groove
7 ^) E# X* q/ k: H- Recess
& x* }9 y& }* ]- Corner
- Bridging of distance
X
Decision approved at the
# B' }# {9 {3 U- `" D( y2009 CTL Plenary
Meeting
Questions:
1) How shall the examples given in IEC 60664 be interpreted for intermediate situations?
( n; Q: `: M: T& g, r2) 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?
0 g; L( R( O  |0,8mm
2 mm
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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
required?
1 ~% r! |+ T' d' d# lDecisions:
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, V, ]& G; [& H: {' j9 SAn 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
5 H9 I4 s* W0 X9 W# x5 S) x! O4 bof the methodology is given in the Explanatory Notes to Question 2."
Ad 2)
+ i# _+ D; u. v% ^! M5 V5 i/ oThe example shall be judged without any bridging of the corner in the cut-out
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creepage = 2,8 mm, no shortcut applicable.
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The sentence shall always be applied whenever the required clearance is less than
3 mm and the allowed reduction of the minimum dimension X shall be referred to 1/3 of the
3 w/ A1 ~4 E  Jrequired minimum clearance.