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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！
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; |& n- j( x7 a. x' l s( f: V3 DProtective imdependance(保护阻抗）是我们经常看到的，但是你理解吗？
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definition: ' ?- C( j+ y, i- S: r6 _$ @/ S: l
protective impedance- ?' X3 }( V3 U) B2 x! @' f
impedance connected between live parts and accessible conductive parts of class II
4 o! r4 w! @0 hconstructions so that the current, in normal use and under likely fault conditions in the, d! T2 b8 f* `( \7 v$ Z
appliance, is limited to a safe value2 m4 N( r- ]6 M9 D/ N' p
" F, y0 [3 m/ N) Q. x; l8.1.4
0 ^/ K1 h8 E6 Z8 p4 x( y& X" k( J8.1.4 An accessible part is not considered to be live if or/ B* Z! M2 C5 |7 Q3 h( Y
– the part is separated from live parts by protective impedance.
8 @4 U4 `" A- U# G9 eIf protective impedance is used, the current between the part and the supply source shall
: W' _* n- J. j: F4 T/ s- Nnot exceed 2 mA for d.c., its peak value shall not exceed 0,7 mA for a.c. and
6 E M0 c4 d3 N1 E. I5 R8 S8 D– for voltages having a peak value over 42,4 V up to and including 450 V, the capacitance7 S: t* ]4 F8 ^
shall not exceed 0,1 μF,2 b8 T+ E7 ] B
– for voltages having a peak value over 450 V up to and including 15 kV, the discharge shall
7 J1 _9 P C4 R- I0 bnot exceed 45 μC,7 G5 \! W7 |! H" ?4 X
– for voltages having a peak value over 15 kV, the energy in the discharge shall not exceed8 L7 _3 m5 b- ?* O! n
350 mJ.5 h- l i! P& B) a8 D* C2 Q3 K8 }
Compliance is checked by measurement, the appliance being supplied at rated voltage.5 N3 V/ U- j- v7 ]8 c- y5 E+ M
Voltages and currents are measured between the relevant parts and each pole of the supply
0 L) v' L; g( j6 R! J+ Hsource. Discharges are measured immediately after the interruption of the supply. The
5 _/ E: |/ c3 H/ j' ~quantity of electricity and energy in the discharge is measured using a resistor having a
3 m/ ~: U, z$ u! ~0 G) L3 }$ R1 cnominal non-inductive resistance of 2 000 Ω.
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5 G0 S* ?; ]( k; G: @3 Q. {Cl13.1
! f8 \3 L$ c2 |$ E1 X' t$ lProtective impedance and radio interference filters are disconnected before carrying out the) w7 M' p9 h* X9 X& N8 M( G5 e; G
tests.7 C: l+ @: u' V2 w0 W! g: p9 H
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Cl16.1
5 H: Y6 a- R6 YProtective impedance is disconnected from live parts before carrying out the tests." D" l! `7 N: S4 a: ~
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Cl22.27
# c) S4 d! ^$ u: m$ k3 b$ u22.27 Parts connected by protective impedance shall be separated by double insulation# p' [* P& g0 \7 ?+ F8 n d
or reinforced insulation.
: ?% [% k, [+ b3 SCompliance is checked by the tests specified for double insulation or reinforced insulation# U6 j9 @; j; M5 _
% K" [( R. A! m% |# Q y) N& S1 T3 rCl22.37
2 A" y" i# F# {( Q2 E: g22.37 For class II appliances, capacitors shall not be connected to accessible metal parts
K- o- d; `+ [; ]* jand their casings, if of metal, shall be separated from accessible metal parts by
1 [3 G8 Q' I3 M9 x0 e# dsupplementary insulation.$ U2 n+ L; d+ t" H0 N5 x
This requirement does not apply to capacitors complying with the requirements for protective
% }/ O' |4 E0 i# k i6 dimpedance specified in 22.42.5 L m$ g/ ?/ l2 @" t! u/ [4 \3 M' N
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Cl22.424 }& P; ~, h. w4 C' }; p2 W+ Y
22.42 Protective impedance shall consist of at least two separate components whose
; L8 i% f* E& I9 Himpedance is unlikely to change significantly during the lifetime of the appliance. If any one of$ O2 l. Q( I. ]7 f2 V8 m, f/ ^
the components is short-circuited or open-circuited the values specified in 8.1.4 shall not be
8 c/ P7 ?, \! c9 K2 n# n, A2 Cexceeded." C& h6 @9 N8 E1 [* C- z8 T
NOTE Resistors complying with test a) of subclause 14.1 of IEC 60065 and class Y capacitors complying with4 J+ `! V) ^! N7 ]( L# }
IEC 60384-14 are considered to be components having a sufficiently stable impedance.
/ T2 _' B- l* y9 h/ z9 q- eCompliance is checked by inspection and by measurement.
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6 T( ]" _# j. L. ~8 D1 N~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0 G4 C6 a; V, s; T
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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