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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！4 t- h V9 w8 j0 g3 H
' d; g) q: C; w$ ?- ~* g/ lProtective imdependance(保护阻抗）是我们经常看到的，但是你理解吗？
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x- N* L; J, B% ~definition:
" F- `2 w8 v" l! vprotective impedance
& e9 |" V* f) B; c4 Eimpedance connected between live parts and accessible conductive parts of class II
' d' B% R4 i6 ` Y: e+ tconstructions so that the current, in normal use and under likely fault conditions in the8 `4 G0 I+ m9 _8 ^4 _- N8 q
appliance, is limited to a safe value
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& v- P" M& `" u7 d- M, M: t# w' B8.1.4
: F5 F. F1 H" u* {3 W8.1.4 An accessible part is not considered to be live if or% L6 m4 ]& h4 ]7 f
– the part is separated from live parts by protective impedance.
- Q" B3 m% l" @- [+ dIf protective impedance is used, the current between the part and the supply source shall6 c" S$ f% [/ R |9 D# b4 X
not exceed 2 mA for d.c., its peak value shall not exceed 0,7 mA for a.c. and
4 p& {: Q; L& Z- L+ X– for voltages having a peak value over 42,4 V up to and including 450 V, the capacitance
- V1 k( N* Z4 L$ r& D' g8 Bshall not exceed 0,1 μF,
! K- L" [: O4 D* O) ^7 A% m" Z. E– for voltages having a peak value over 450 V up to and including 15 kV, the discharge shall
" f" V& {% V; ]9 l, p9 T4 Jnot exceed 45 μC,: E* C M7 l+ U& N
– for voltages having a peak value over 15 kV, the energy in the discharge shall not exceed5 E0 h# H/ q7 O$ F
350 mJ.3 [/ _9 Q! ^5 J! }
Compliance is checked by measurement, the appliance being supplied at rated voltage.
b4 i" e+ {7 _3 rVoltages and currents are measured between the relevant parts and each pole of the supply
8 B4 r1 Q! A% `9 J7 U2 k' Hsource. Discharges are measured immediately after the interruption of the supply. The
4 U3 G' Y8 `$ X) M: uquantity of electricity and energy in the discharge is measured using a resistor having a
2 l- v& f7 U# Q6 b- [' unominal non-inductive resistance of 2 000 Ω.
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Cl13.1, m& `) \3 c, C; e
Protective impedance and radio interference filters are disconnected before carrying out the- I/ M, F1 x( ?# V: ~" a
tests. F) Q- a6 l/ n3 x# t
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Cl16.1+ H/ g3 s M2 r" D
Protective impedance is disconnected from live parts before carrying out the tests.& [$ c6 j. t# d2 n* U
7 a" J, f# H* |8 A3 S3 Z
Cl22.27
- Z) _# e! R' a& V! n( @. k22.27 Parts connected by protective impedance shall be separated by double insulation
. ^. e# `9 c1 D- ]/ ]or reinforced insulation.5 B0 ]3 {/ z7 ~2 P' m4 z4 x/ b% w7 v
Compliance is checked by the tests specified for double insulation or reinforced insulation/ j, @; ]% }0 W% y/ Q# n$ K+ ~0 B* k
& j3 v3 n( i q: ^- \/ UCl22.37
) w0 K3 x! N0 ]- n O22.37 For class II appliances, capacitors shall not be connected to accessible metal parts6 {- r7 c1 @+ g7 C8 u0 a
and their casings, if of metal, shall be separated from accessible metal parts by7 f$ t& d& R$ |7 M
supplementary insulation.* h" }6 I: S" [0 [; Z8 e6 z- C+ ]
This requirement does not apply to capacitors complying with the requirements for protective- X0 p- |- u" f% K: B/ v1 z
impedance specified in 22.42.
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$ E. k. ?; X7 ^: Q& rCl22.428 J8 m* C' D' E) l" {& ~1 W
22.42 Protective impedance shall consist of at least two separate components whose
, I: N1 L$ @9 \ T# ~5 Qimpedance is unlikely to change significantly during the lifetime of the appliance. If any one of
# p2 m3 a. L: J# Y. Dthe components is short-circuited or open-circuited the values specified in 8.1.4 shall not be
0 @; W$ i0 K, Q) Q3 A2 M7 ]9 lexceeded./ e, t1 A: a ^
NOTE Resistors complying with test a) of subclause 14.1 of IEC 60065 and class Y capacitors complying with8 G5 `, w) U. _; U( y
IEC 60384-14 are considered to be components having a sufficiently stable impedance.
6 Q1 Q4 Q4 z4 R' N/ _; qCompliance is checked by inspection and by measurement.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~9 Q7 D1 J* g t- X, m! 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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