DSH 568 Varistors (VDR’s) across the mains

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广东安规检测
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DSH 568 & O4 T+ \% P- ~7 g! H) j

Varistors (VDR’s) across the mains

19.11 $ H, `+ B* v) W2 i3 w0 l# n

60335-1(ed.4)

! `4 S3 u6 _5 l. e. w, _: S* `, `Question:
8 _4 B* R/ D- |$ h4 p1 C+ oReports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies.
- A) F8 Z+ x9 cActually, the practice of one Certification Body is now being a market factor.
% _& N, T  }9 K! w* GBased on above concerns we ask for clarification:
1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted.
% I7 V7 i( A( e! @2: Can any of the decisions (made by OSM/EE) be accepted?
- A: VDR’s across the mains are accepted if the VDR is separately certified according to IEC 61051-1 or according to CECC 42200.
4 q' g) k1 H7 v' E& p! G- B: VDR across the mains with a protective device to guard against short-circuit is acceptable.
- 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.
4 Z: g. |2 k9 w" T  ^0 @. bDecision:
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).
; G; E7 s6 r% S9 A9 `  Y' G2. VDR’s are short-circuited regardless of compliance with IEC61051-1, when tested according to Subclause 19.11.2 of IEC60335-1(2001).
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