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发表于 2010-3-4 10:06
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好像大家都没有兴趣，这样我来抛砖引玉！+ N- K9 @' q& w: L
% ~5 Q2 c& a( K' y. vProtective imdependance(保护阻抗）是我们经常看到的，但是你理解吗？
/ B7 N4 u# ?6 D0 i
' s3 B* i' r& D. b5 u( ]6 d5 R: Xdefinition: " i, m1 i# B z
protective impedance5 f' \5 f4 x6 O/ f& ?% O: ?
impedance connected between live parts and accessible conductive parts of class II9 @7 T, m' U" X: S
constructions so that the current, in normal use and under likely fault conditions in the. i. u. g' F0 _/ n1 T* y
appliance, is limited to a safe value
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8 n9 ?4 S% d' \4 [: m, s$ D8.1.4+ `! _: e8 O( X4 J9 @7 x7 y
8.1.4 An accessible part is not considered to be live if or7 m% M9 I4 l7 F. g2 k7 i
– the part is separated from live parts by protective impedance.
0 t' z' r+ A# |6 y, x+ e% [6 [ S! pIf protective impedance is used, the current between the part and the supply source shall0 o6 l/ x) E$ a# ]
not exceed 2 mA for d.c., its peak value shall not exceed 0,7 mA for a.c. and& d! s s# W7 d% @( n
– for voltages having a peak value over 42,4 V up to and including 450 V, the capacitance
! ]. G7 _7 L5 Y: n3 Q8 Qshall not exceed 0,1 μF,
* }1 M- B2 `# b5 {2 e– for voltages having a peak value over 450 V up to and including 15 kV, the discharge shall. x# N+ s f6 ~+ |+ N
not exceed 45 μC,
% b7 B: t: l+ | K0 E– for voltages having a peak value over 15 kV, the energy in the discharge shall not exceed1 q2 F+ K/ q& `; A* y& g" _
350 mJ.
; ?3 d' R( C. ^# _Compliance is checked by measurement, the appliance being supplied at rated voltage.6 s0 C2 u. s* ~7 p' I; v
Voltages and currents are measured between the relevant parts and each pole of the supply( X+ N' Z) Y- j2 Q
source. Discharges are measured immediately after the interruption of the supply. The
4 G, q8 {- k1 e* w; ]9 Kquantity of electricity and energy in the discharge is measured using a resistor having a, ?) @! M! K8 a2 W, p- q! ?8 S! @5 C
nominal non-inductive resistance of 2 000 Ω.8 n) C& `; f; P* ^4 h: b6 }8 }4 v
- K& x9 {! L& E6 H5 G8 p. o5 m0 SCl13.1* q Z, j( k+ C
Protective impedance and radio interference filters are disconnected before carrying out the4 C/ Y5 U4 u1 ^7 d( b U9 C; G& [
tests.4 x0 U; `6 x9 p9 ?* x
; ?5 |/ O& t& q, K( cCl16.1
! |( P& W, A$ X" }1 }+ xProtective impedance is disconnected from live parts before carrying out the tests.8 Q1 `6 r+ P0 M6 B
( F2 g5 R2 B, w2 M: H. _Cl22.27
1 y5 g6 B' {/ z9 e: E22.27 Parts connected by protective impedance shall be separated by double insulation
^! b% d4 W8 ~2 F3 b* mor reinforced insulation.; @2 O( N: \& B' a
Compliance is checked by the tests specified for double insulation or reinforced insulation
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. \" \3 V; G$ S: NCl22.37
% L, Y1 j4 o3 V$ ~. ?' K22.37 For class II appliances, capacitors shall not be connected to accessible metal parts3 N: y. Z0 o6 @
and their casings, if of metal, shall be separated from accessible metal parts by
+ J8 O+ P- e4 esupplementary insulation.; F+ ^4 c( H9 X; s
This requirement does not apply to capacitors complying with the requirements for protective
, O) Q! I% ^1 mimpedance specified in 22.42.. ^$ t. B) S) D) O3 h
( D5 d( j- |7 J- aCl22.42
; e) ?- S8 u) L22.42 Protective impedance shall consist of at least two separate components whose6 a$ n) r' n) k* Q( Y" M+ ^
impedance is unlikely to change significantly during the lifetime of the appliance. If any one of# @4 I- T! o3 e* A+ n+ {1 {% @
the components is short-circuited or open-circuited the values specified in 8.1.4 shall not be
" E9 }. w- N( D+ K2 gexceeded.
z* E. n$ P' e( G& DNOTE Resistors complying with test a) of subclause 14.1 of IEC 60065 and class Y capacitors complying with
8 r; a7 A: R+ ^) i9 a6 [IEC 60384-14 are considered to be components having a sufficiently stable impedance.# Q1 t" v2 s5 P
Compliance is checked by inspection and by measurement.
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* I' ]" ]# E# [3 D~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8 ]. O5 R* V: r5 M/ y3 Z9 s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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