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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）. 0 ^# i$ A" }3 T* ^% [, _
2.1.1.7 Discharge of capacitors in equipment0 h2 P& C: J8 Y% Y }
Equipment shall be so designed that, at an OPERATOR-accessible external point of ! r ^+ D3 c2 y/ N
disconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors 4 n. c# u2 D7 i
connected in the equipment is reduced. No test for shock hazard is required unless the
- l$ O l2 N% G: W1 {$ mnominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c. . P/ ]) V3 H- N. F9 ~
Compliance is checked by inspection of the equipment and relevant circuit diagrams, taking
; E4 D: k# z: f: P$ b1 X8 \into account the possibility of disconnection of the supply with any on/off switch in either / q: K* @& L) ^; z/ J$ @
position.
% W% {8 Q+ ?3 v# J% bEquipment is considered to comply if any capacitor having a marked or nominal capacitance - N6 N0 v' U5 ~) i
exceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge
9 f: K/ L* a6 H5 B. dresulting in a time constant not exceeding:# g7 x0 ~9 j8 R3 |
− 1 s for PLUGGABLE EQUIPMENT TYPE A; and
& B/ p7 |5 H' z9 u0 x− 10 s for PLUGGABLE EQUIPMENT TYPE B.
, d3 D! V" k( D. X& l$ ~& ~The relevant time constant is the product of the effective capacitance in microfarads and the ; u! Z" h7 |! i1 j6 O) K
effective discharge resistance in megohms. If it is difficult to determine the effective * }( o; I) o- \. j/ ]$ `2 y
capacitance and resistance values, a measurement of voltage decay at the point of external
$ @4 j! \% P4 t4 pdisconnection can be used. When conducting the voltage decay measurement, the result is2 }' ~- o% a$ E9 I
the measurement is either made with, or referred to, an instrument having an input impedance 5 w$ b; l9 U2 r9 A: n3 l. ?
consisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of
% _( ~! B( R* |" Z* G20 pF ±5 pF 25 pF or less. |
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