Varistors (VDR’s) across the mains 5 U; V9 v! r; {, S( H
19.11& t$ {4 b4 U. F8 f1 M. |
60335-1(ed.4) 6 f7 F9 w2 f6 p! P, b
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Reports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies. 2 w: ~$ w. O: h0 wActually, the practice of one Certification Body is now being a market factor.# X( j5 u! K9 u! c* M m+ w
Based on above concerns we ask for clarification:5 U8 x: Z; k& e4 @! s1 J7 k
1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted. ( u% @4 K2 D: n+ ]; K7 f2: Can any of the decisions (made by OSM/EE) be accepted?' ^- u/ I! D, G' ^/ H
- A: VDR’s across the mains are accepted if the VDR is separately certified according to IEC 61051-1 or according to CECC 42200.9 w# p8 z/ O9 v
- B: VDR across the mains with a protective device to guard against short-circuit is acceptable.5 a4 X1 k+ H, ]" K2 S& n
- 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.% Y$ p3 H D1 l/ w7 Y [
Decision: ; n8 z4 [' ^% V4 R1. 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). 2 c; v! @2 l3 F, Z$ b- _2. VDR’s are short-circuited regardless of compliance with IEC61051-1, when tested according to Subclause 19.11.2 of IEC60335-1(2001).+ c! Z: _( O4 d% j- w! f; j
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