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http://bbs.angui.org/thread-104454-1-1.html
! N; n# p4 f1 X; z0 v& _) E7 gVaristors (VDR’s) across the mains9 h8 ?7 u. l) Q( ?$ t0 [
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Question:
( E& u3 S* p" h2 B% x Z3 R" iReports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies.& o3 q+ [. Y7 ?
Actually, the practice of one Certification Body is now being a market factor.
9 Q+ ?3 `' u, u6 y" U- OBased on above concerns we ask for clarification:+ n. J) F2 r- p' Y1 u
1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted.( z( X$ V. V9 ?
2: Can any of the decisions (made by OSM/EE) be accepted?( f, @! Q: I& }4 ~9 ?* s% d: H3 k7 x+ f
- A: VDR’s across the mains are accepted if the VDR is separately certified according to IEC 61051-1 or according to CECC 42200.2 K' C0 w5 D7 a; g+ F& C" g% i3 X
- B: VDR across the mains with a protective device to guard against short-circuit is acceptable.9 M6 ?7 h5 n' K
- C: If A and B are acceptable, should, because of the fact that VDR’s may burn or burst during life-time due to an increasing temperature stress caused by increase of leakage current with a number of switching cycles in the VDR, a thermal interrupting device on the VDR connected in series with the VDR be required.& a& o4 _ t+ z }- X
Decision:: J+ N- C# {/ ^2 l/ K) ^) C
1. VDR’s are not short-circuited if they are used within their manufacturer’s declared specification, when tested according to Sub-clause 19.11.2 of IEC60335-1(1991).; H4 I7 k3 ?" ~+ d6 w* J5 V! M
2. VDR’s are short-circuited regardless of compliance with IEC61051-1, when tested according to Subclause 19.11.2 of IEC60335-1(2001).6 K$ P$ D# @2 c# O- s
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