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楼主 |
发表于 2014-5-17 10:32
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没有说要在故障情况下（open R1）.
7 y+ ~. ~& Z, q2.1.1.7 Discharge of capacitors in equipment# e! }! ^4 B! \' T( P6 G
Equipment shall be so designed that, at an OPERATOR-accessible external point of
4 Z* i% R$ e7 N4 ~ j5 {disconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors / ?* Q8 e9 S0 U& m
connected in the equipment is reduced. No test for shock hazard is required unless the
4 M* |7 @$ ]+ a7 \nominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c.
% l% U. ^' V7 u, f+ {Compliance is checked by inspection of the equipment and relevant circuit diagrams, taking . {8 B( [7 t+ ~5 G
into account the possibility of disconnection of the supply with any on/off switch in either 0 a2 @* c4 q# M9 ~5 `- Y% E0 h
position.
% F8 q0 I. N/ Y/ ZEquipment is considered to comply if any capacitor having a marked or nominal capacitance
: a5 Y, L9 r+ t. Z* s; E; K$ D/ fexceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge
g" v( _) u9 T. p9 Vresulting in a time constant not exceeding:* v* w4 ~9 D+ y. O: Q
− 1 s for PLUGGABLE EQUIPMENT TYPE A; and: |4 e( P$ ]% W1 \ g& o
− 10 s for PLUGGABLE EQUIPMENT TYPE B.
! ~+ |) d4 Z+ m! S, DThe relevant time constant is the product of the effective capacitance in microfarads and the
6 Q- _) ~0 c7 k8 F# |effective discharge resistance in megohms. If it is difficult to determine the effective
% U! ?' j7 n" S: [. o0 \7 ]capacitance and resistance values, a measurement of voltage decay at the point of external ' r4 A1 Q+ Q6 G4 L K8 q
disconnection can be used. When conducting the voltage decay measurement, the result is4 k& A. _5 k, R/ }2 L: W8 e5 Z& t# o
the measurement is either made with, or referred to, an instrument having an input impedance
5 n2 n6 T R/ r" u8 V y2 }consisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of 8 r9 Q* W& l; F7 i0 o& F- {5 a8 T8 V
20 pF ±5 pF 25 pF or less. |
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