DSH 568 Varistors (VDR’s) across the mains

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广东安规检测
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DSH 568 9 N! O2 r- K; A

Varistors (VDR’s) across the mains

19.11 % l. b8 u9 g: n1 Y

60335-1(ed.4)

Question:
$ M9 n) }0 M  @3 \; l) eReports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies.
Actually, the practice of one Certification Body is now being a market factor.
, H- A& H" Z2 l$ u( h6 l4 K! lBased on above concerns we ask for clarification:
/ R4 w5 F4 K& \2 v4 [' D1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted.
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.
- 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.
' A( G7 u( l) Z4 R& |/ T+ c3 xDecision:
0 F! `7 t4 _, n5 L1 q, Q1. 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).
/ t/ |. N; f: r+ r) ]& T5 V2. 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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