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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）.
' O( k* F, ], }# p2.1.1.7 Discharge of capacitors in equipment9 @0 P$ C# \3 E* w) j2 O6 f
Equipment shall be so designed that, at an OPERATOR-accessible external point of
- S0 N0 i/ ]" `9 u6 Q+ S! ldisconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors
9 v" s& g/ V V$ b/ Econnected in the equipment is reduced. No test for shock hazard is required unless the
; Q" Z$ J2 C8 Lnominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c. 1 ]: |7 c# E3 q7 D' p
Compliance is checked by inspection of the equipment and relevant circuit diagrams, taking
8 M7 I: x! [. W; P7 N' ginto account the possibility of disconnection of the supply with any on/off switch in either
* J; ^: }( A; o, Sposition., C$ b$ G; l) t: I4 S+ c) Z4 ?
Equipment is considered to comply if any capacitor having a marked or nominal capacitance
4 u5 u7 o" K, dexceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge
* j, K7 _8 @: w0 x3 h1 b" Eresulting in a time constant not exceeding:! o) o9 m, R9 v# p2 ?# o* \
− 1 s for PLUGGABLE EQUIPMENT TYPE A; and" O& j) t7 ~# j& N4 W; n/ g
− 10 s for PLUGGABLE EQUIPMENT TYPE B. 9 N5 ^' U1 `7 @9 W) H0 T9 _! L
The relevant time constant is the product of the effective capacitance in microfarads and the
3 B3 n: i8 p {5 ^2 u D6 Jeffective discharge resistance in megohms. If it is difficult to determine the effective
y; l h1 K4 U: l( Pcapacitance and resistance values, a measurement of voltage decay at the point of external $ k) @% Q4 c% l
disconnection can be used. When conducting the voltage decay measurement, the result is
1 c `- v/ T9 ^ pthe measurement is either made with, or referred to, an instrument having an input impedance
/ i7 \/ [8 M: f- f8 bconsisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of
8 K6 l5 G& ~1 G20 pF ±5 pF 25 pF or less. |
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发表于 2014-5-16 18:02
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