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+ S$ d( q; K8 j. i9 oStandard: IEC 61558-1/1997
6 b0 Y8 u$ C9 }) V5 B/ p- M) L3 ^Sub clause: 26.20 I7 s# J* }8 E, Q. Q2 n; h1 ^
Sheet N°: 594/062 w$ d& S3 c' ?& m; F, O( x
Page: 1(1)
8 {5 W7 X" [; b8 R. O: YSubject: Creepage distances# C$ p2 [* L# D+ v) n# f( G
Key words:8 ?# K* `. c# ]( T# o
- Creepage distances
/ |% H# C r. b: k- Reduced value4 N( e' p7 x' b' p0 @1 f
- Impregnation
$ d5 K' `; ^1 {4 BMeeting:: y$ \) V, `0 k. n* C% x% z
Decision confirmed" q R2 {( [1 E* {& l; q& l$ b& n
at 44th CTL meeting
% c8 \5 L) b" v$ X, N5 iQuestion: Clause 26 of the standard lists several requirements regarding creepage- S) K$ ^6 q/ p0 c
distances, clearances and distances through insulation. In particular, paragraph 4
$ `9 x D! A: j8 zof subclause 26.2 states: “The reduced values shown in Table 13, C.1 and D.1
' Q' o6 ]. P! h' s# [& \can be used when separation is made by the use of impregnation, potting, or by! ?3 C6 D) s( i: Q3 C
the use of adhesive bonding tape covering the windings, provided that the tests
( ~$ {4 L$ D' {8 z6 h. N2 Gof 4.1.1.2.1 of IEC 60664-1 are fulfilled”. To check whether the parts are+ t+ f& z. n$ k
adequately potted, impregnated or cemented together, the tests according to2 Q, b# { c5 n9 n1 u5 y1 P% n
procedure A) or B) are conducted. If a transformer is impregnated or potted on2 A; j a1 M: R* H( |) n, S" [
the outside only, and the impregnation material has not penetrated inside it, e.g.
0 l/ {4 S7 F4 w3 z7 zbetween primary and secondary winding or between winding and core, can the8 Z( p8 n1 U0 m' b% R
reduced values of Table 13, C.1, D.1 be taken into account?
9 W! `6 s7 f# k" X# ~Decision: Yes, According to the IEC 61558-1, it is not required that the impregnation or9 F) B6 A- t9 r0 q5 b' u4 f
potting material must penetrate into all parts of the transformer. The criteria- h$ s+ g% j8 {8 t2 J) Q
for acceptance is the tests described in clause 26. The second edition of IEC
! x9 _7 N/ S5 b/ i61558-1 is clear in this respect.( f6 S7 x' p) J5 @" p/ u0 k
0 F# D4 Y3 N) @ q5 `& V t* [$ w5 i
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