DSH 568 Varistors (VDR’s) across the mains

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DSH 568 + i/ _1 \$ R- K  D. N

Varistors (VDR’s) across the mains 3 q! o$ z& b- C1 ~4 L; s

19.11 ' ]4 [+ @6 a& I

60335-1(ed.4) ( {$ O/ d! o7 l0 r

# f+ o2 ?0 o# I* CQuestion:
Reports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies.
) X. u4 W: `) t# B# oActually, the practice of one Certification Body is now being a market factor.
4 H0 D4 V( m1 ^$ MBased on above concerns we ask for clarification:
! k2 i1 q8 i# w2 Y" g1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted.
9 B, X' b0 q+ `) v: f4 d# Y2: Can any of the decisions (made by OSM/EE) be accepted?
& n* |+ U+ A" X% H- A: VDR’s across the mains are accepted if the VDR is separately certified according to IEC 61051-1 or according to CECC 42200.
$ E, C: ]0 }$ O- 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.
. O2 z& K3 \# T; w  m, p+ FDecision:
: W& o' [- }; T+ |7 l+ E/ }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).
7 d3 P  H6 F* b% Z$ ?2. 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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