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好像大家都没有兴趣，这样我来抛砖引玉！
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4 l! K! x" ]7 I; e# oProtective imdependance(保护阻抗）是我们经常看到的，但是你理解吗？ D* L' F" t1 m5 b
* k L H9 U: l8 k& U- ?- s
definition: & }( a/ |6 [' _$ J- k! l
protective impedance
, t9 |+ q' p: p! d7 {" d5 cimpedance connected between live parts and accessible conductive parts of class II
, k0 M- ^$ e. k+ G+ Tconstructions so that the current, in normal use and under likely fault conditions in the2 X& Z- P. x- H6 @# U2 y" O
appliance, is limited to a safe value2 @* w. o1 }. z$ v5 }; I+ Y
. q0 c7 r7 S# ~
8.1.4
6 l* `/ f/ m$ X7 L3 W8.1.4 An accessible part is not considered to be live if or
: y: V- g) a! O0 f! Y– the part is separated from live parts by protective impedance./ H6 s! J# m& u/ _; H) F
If protective impedance is used, the current between the part and the supply source shall$ F( }% ^( w G3 o2 O5 ^5 J- a8 C) F: E
not exceed 2 mA for d.c., its peak value shall not exceed 0,7 mA for a.c. and
A% C0 o, X, j8 n9 Q- [8 b– for voltages having a peak value over 42,4 V up to and including 450 V, the capacitance
; m( r# a( V. R1 L1 d P) ]; jshall not exceed 0,1 μF,
) z+ @( R! ~6 b– for voltages having a peak value over 450 V up to and including 15 kV, the discharge shall. f* r. _5 x" n5 T
not exceed 45 μC,
. B) ?7 |7 O7 I# }– for voltages having a peak value over 15 kV, the energy in the discharge shall not exceed/ e& I% g8 i* q- x* Z$ Q
350 mJ.1 H4 g" n, @& Y; `9 E/ R
Compliance is checked by measurement, the appliance being supplied at rated voltage.
. Q5 Y& ^4 N9 @ d; Z) j% {Voltages and currents are measured between the relevant parts and each pole of the supply) n! S/ |! [; l
source. Discharges are measured immediately after the interruption of the supply. The
2 \6 ^' D" I/ A' `quantity of electricity and energy in the discharge is measured using a resistor having a
4 p% |/ P. G2 j; J6 o5 l2 o( tnominal non-inductive resistance of 2 000 Ω.
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* o; l2 ?/ d1 S- W$ c$ g, t" MCl13.1
8 @3 |* s- \ e' E6 m. z+ v0 BProtective impedance and radio interference filters are disconnected before carrying out the. s2 P' T7 I% E6 l- `+ F7 u
tests.) m) ~+ s4 `6 e, b7 [9 ~+ y9 {
6 G1 o3 m5 W6 m/ n% D0 r' Z2 Q( e
Cl16.11 X* |9 ]* c1 d' O& ?2 x" s
Protective impedance is disconnected from live parts before carrying out the tests.
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0 j3 F; f2 U8 [5 l% qCl22.27( x. }' C* h# x' D( B2 |
22.27 Parts connected by protective impedance shall be separated by double insulation5 v" @4 [6 z9 B
or reinforced insulation.$ h- d Z f2 L8 B( v
Compliance is checked by the tests specified for double insulation or reinforced insulation* b/ x( a% K4 x, A. p' W* C
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Cl22.37
. j% @- ?, A1 H, T8 k22.37 For class II appliances, capacitors shall not be connected to accessible metal parts# a9 `. ]) ]( _% {- V+ V4 z
and their casings, if of metal, shall be separated from accessible metal parts by
5 A+ _, x: s/ S xsupplementary insulation.
) }6 H4 V. B) j/ vThis requirement does not apply to capacitors complying with the requirements for protective; c* l. t# S0 b, l# u. u
impedance specified in 22.42.
/ {- @" {) r1 s
8 S" G. i7 ?/ K/ m4 u# v3 bCl22.42
2 w1 N' H- V& L3 q4 Y5 \! l/ v+ w22.42 Protective impedance shall consist of at least two separate components whose1 K0 ?9 {( `: h- g
impedance is unlikely to change significantly during the lifetime of the appliance. If any one of( U2 R" L. }3 h0 |
the components is short-circuited or open-circuited the values specified in 8.1.4 shall not be- c( J; z( J4 g1 e6 ~
exceeded.6 L* p, P6 n6 c0 _$ i0 C+ P
NOTE Resistors complying with test a) of subclause 14.1 of IEC 60065 and class Y capacitors complying with
1 j) Y% g! I4 O' v! k. MIEC 60384-14 are considered to be components having a sufficiently stable impedance.: C) E) ]) J1 u. N) E
Compliance is checked by inspection and by measurement.
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+ ~) ^2 ?* s! {7 W( S# n8 s3 P~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~, p( j0 p( u+ I p0 K
这么多的要求中，你碰到过什么样的案例？是怎样评估和解决的？ 一起拿出来分享吧！ |
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发表于 2010-3-3 16:55
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