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http://bbs.angui.org/thread-104454-1-1.html6 S2 D0 e/ U0 B% v8 @
Varistors (VDR’s) across the mains5 F; r. N5 }1 ^# K
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Question:
! X) x" z% ^8 T5 `6 iReports from different Testing Laboratories and clients expose essential differences in interpretation and testing practice between laboratories and/or Certification Bodies.
7 d' N* }; o! O$ C" tActually, the practice of one Certification Body is now being a market factor.
5 A1 }- i5 C: f7 qBased on above concerns we ask for clarification:; j# g1 }$ `( Y
1: Shall Cl. 19.11 be strictly followed or can solutions given under 2. be accepted.
* f5 Z" c4 ]( |6 m9 L( t2: Can any of the decisions (made by OSM/EE) be accepted?
; e% N0 {0 X+ p0 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.
% u: e, l2 M+ W- B: VDR across the mains with a protective device to guard against short-circuit is acceptable.: ^+ N* C% w( A- Z9 _6 o
- 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.
1 U+ G6 U" L7 [+ \" S) M, iDecision:' @3 e3 E8 ~3 f/ E2 C* K( r
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).
# R3 H0 m; X: Y7 _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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