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need to note the clause below:5 {8 J& o- N( g# ?
IEC60950:
" n+ e( p0 p# N2 y$ B1.5.9.2 Protection of VDRs, w( N$ k8 [1 }* D$ W
For protection against5 W- i& @8 R) r$ N9 D% R% e
− temporary overvoltages above the maximum continuous voltage,
* ?2 o9 `; D( Y n' S. w+ |0 f− thermal overload due to leakage current within the VDR, and
, W ]1 e: d( Y" J5 j7 l. x( s− burning and bursting of the VDR in the event of a short-circuit fault,
6 B: V# @' @/ b( ?) gan interrupting means having an adequate breaking capacity shall be connected in series with
& ~' ]% a8 Z! Vthe VDR. This requirement does not apply to a VDR in a LIMITED CURRENT CIRCUIT.7 s, M, N& a. D, _& T- I1 Q8 x5 D; G; G
( l/ n9 i( Z/ |$ b' t LIEC60065:
! c0 g( |6 Q0 B: Z) n' N– thermal stress
: n/ {- v& x& p6 R0 r# N, ZFor apparatus with nominal MAINS voltage of <150 V, the apparatus and a test resistor* }# T- _! O* P: _2 u! b
connected in series with the apparatus shall be energised from an a.c. source of 250 V.
6 O; B" W& _9 L3 N7 E% M$ f( JThe voltage source shall be applied for 4 h or until the circuit path through the varistor* C4 h' |# G; n# m
opens for each of the test series resistance values: 2 000 Ω, 500 Ω, 250 Ω, 50 Ω. A7 |9 x7 f! x- c8 P0 J. K$ E
separate apparatus shall be used for each resistor value, unless damage from the previous
! s$ A8 z! W; g, ^4 B" Wtest has been repaired.
! H( F+ H1 J: \At the end of each test, the apparatus shall comply with clause 11. |
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发表于 2010-4-22 16:26
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