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发表于 2014-5-17 10:32
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没有说要在故障情况下（open R1）.
# k2 [6 ]! s' U+ v E6 d2.1.1.7 Discharge of capacitors in equipment
V: Z* v9 @8 `: `Equipment shall be so designed that, at an OPERATOR-accessible external point of " [, {+ G$ Z% t
disconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors
2 y4 z0 ~- k1 O3 b! E: U$ ~, sconnected in the equipment is reduced. No test for shock hazard is required unless the
2 ^( M% T% q# s, C M3 b6 rnominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c.
; Z3 a: E: {' d3 H, ZCompliance is checked by inspection of the equipment and relevant circuit diagrams, taking
- o( \! Y k/ x$ c' f, [into account the possibility of disconnection of the supply with any on/off switch in either
& q& u- \" N, O7 S+ x: Vposition.
+ o, q# V3 H3 G8 {* ?' _Equipment is considered to comply if any capacitor having a marked or nominal capacitance & }8 C5 E& D: Z$ s
exceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge " r, t. F4 P9 M0 W
resulting in a time constant not exceeding:
4 W" N) b2 @7 I* N0 P4 i− 1 s for PLUGGABLE EQUIPMENT TYPE A; and3 X. D' T: W" Z. L+ m: m# b1 T
− 10 s for PLUGGABLE EQUIPMENT TYPE B.
8 M/ _1 q8 E* J) A, @The relevant time constant is the product of the effective capacitance in microfarads and the
6 F A! x1 g% v- p+ [effective discharge resistance in megohms. If it is difficult to determine the effective
. m) \* y1 c6 W* t' \+ p* |/ jcapacitance and resistance values, a measurement of voltage decay at the point of external 1 [7 P. F' p3 C+ m3 m2 u" `% _
disconnection can be used. When conducting the voltage decay measurement, the result is
; E; m$ X J/ Y( |! s# pthe measurement is either made with, or referred to, an instrument having an input impedance . B! T: w+ A* N: s) n) e, l
consisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of
' E8 c m/ K2 V5 u! @/ u1 q3 |20 pF ±5 pF 25 pF or less. |
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