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引用第0楼老猪屁屁于2007-07-02 19:52发表的 求教:关于保护阻抗 :9 w, E, g$ R8 Z# q) C
由于接触的产品比较少,一直没有对保护阻抗有直观的了解,只硬生生的记得标准上的一句定义,哪位大佬能举一个典型的实例?
5 p$ P. r% s8 s K. Z- \另外13章和16章中泄漏电流测试的操作和原理主要区别在哪里?(除测试条件一个在温升测试之后,供电测试,一个在防潮测试之后,不供电测试)
2 I7 S: O" |+ s为什么13章测试需要断开保护阻抗和滤波器?而16章只需断开保护阻抗?是否16章断开滤波器测试时限值应该double?
& Q2 c2 O7 Z( f' J* z3 e7 R+ J5 Y急切的期待大佬们指教!
; U! m9 `( I9 D0 a其实这个贴子偶一直都在关注著,,,希望能看到高手来解答。。。+ s6 @# G( a. d" C
0 p- I2 B* P" Z2 b! ?(既然高手没有出现,而贴子快沉到底了,偶就只好硬著头皮出手了[s:3],说得不妥的地方,大家不要扔板砖哦)
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3 O, L2 w3 d7 \" A3 n' n记得电源网的Qing-qing兄(即安规网的包子熊)也问过"保护阻抗“的问题,(问题的地址:http://www.dianyuan.com/bbs/d/51/146409.html)
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, P9 H# a5 |8 p1、保护阻抗:连接在带电部件和II类结构的易触及导电部件之间的阻抗,在正常使用中及器具出现可能的故障状态时,它将电流限制在一个安全值。 |: X& {$ i; `
Q:以上的定义是不是在说类似PTC元件的东东?它具体是怎样应用的呢?能否举个实际的例子? ! H$ l+ T, Y% D8 z" }( L$ D
8 V1 A, y/ b$ C( h; h我当时的回答是:6 U: _& e: \+ _! o( I7 u
5 e% a& k$ ]8 O% a1 E我的理解: / `6 h' U1 ?0 a' w6 j& D' F" D
保护阻抗可是一个电子元件, 也可以是某个电路或某个电路的一部分, PTC当然可以用作保护阻抗.
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5 o; r( T+ D5 s显而易见地,我当时的回答是错误的。。。6 j; i" l6 _5 K
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保护阻抗首先是在IEC 60335-1-2006中的 Clasue 3.3.6 中提出定义,
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7 q# L* L, M3 T# `6 _protective impedance
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impedance connected between live parts and accessible conductive parts of class II constructions so that the current, in normal use and under likely fault conditions in the appliance, is limited to a safe value.. s w( t3 Q5 A% R+ U
5 }" m9 E' }3 E8 O' L6 P6 v5 n接著在Clause 8.1.4 中得到了应用,
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' C# p5 J1 q9 O7 YAn accessible part is not considered to be live if1 U8 p: W6 _7 w% l) F" E
9 c- w* Z, I) \6 ^6 M8 I– the part is supplied at safety extra-low voltage, provided that2 a7 N3 X/ M* A
• for a.c., the peak value of the voltage does not exceed 42,4 V,* g( M. N- c9 ?1 v0 G4 [, c
• for d.c., the voltage does not exceed 42,4 V,; d. E+ \0 @% ^
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– the part is separated from live parts by protective impedance.
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紧接著在下面进行了限制,
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( O2 q( G# q* _4 ?8 H% enot exceed 2 mA for d.c., its peak value shall not exceed 0,7 mA for a.c. and2 U1 e; B6 U; U
– for voltages having a peak value over 42,4 V up to and including 450 V, the capacitance shall not exceed 0,1 F,8 n& H# d' S! y
– for voltages having a peak value over 450 V up to and including 15 kV, the discharge shall not exceed 45 C,
6 j9 e* W% X" i" R– for voltages having a peak value over 15 kV, the energy in the discharge shall not exceed 350 mJ.
9 Z& `( }/ w- x) D+ T) p' Q" d+ j7 eCompliance is checked by measurement, the appliance being supplied at rated voltage.' D, u) p3 l y; A
Voltages and currents are measured between the relevant parts and each pole of the supply source. Discharges are measured immediately after the interruption of the supply. The quantity of electricity and energy in the discharge is measured using a resistor having a nominal non-inductive resistance of 2 000 .
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将这个要求和IEC 60950-1-2006 的clause 2.4.2 条相比,要求何其相似也。
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1 \8 l% S1 A5 S6 f" L根据“protective impedance”的定义和要求,我就大胆地肯定,“protective impedance”就是 IEC 60950-1-2006 中的“Limited current circuit”。1 c# g, I1 Q6 e) S X, [
% w& t. i; v3 `0 \. Q) V2 F# S0 S这样就简单了,大家都知道,“Limited current circuit”主要是指输入与输出之间串接的电阻(普通电阻)、电容(Y电容)等。这也适用于“protective impedance”。, x3 R! ]2 |5 @, @& @+ l
* [" F9 a4 s4 T$ b( @如果大家看到了器具的输入与输出(要隔离的)之间串接有电阻或/和电容,这电阻或/和电容就是“保护阻抗”,并要满足8.1.4条对“保护阻抗”的要求。+ U- ~( I! Z. |7 C3 k4 |; t; Z
& s% ?' } }, B) B1 W+ a K$ ^2 b. w未完等续。。。 |
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