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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）.
, a# z. q- K5 R0 e2.1.1.7 Discharge of capacitors in equipment2 w" u8 C+ a0 e2 E0 D$ {( a
Equipment shall be so designed that, at an OPERATOR-accessible external point of 4 G# q% P& _' ^0 K b
disconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors
: }& Q( _+ w- Yconnected in the equipment is reduced. No test for shock hazard is required unless the
1 t- F% W. s% ~6 B- T0 Cnominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c. * ?: W" _* W( \4 ^# U
Compliance is checked by inspection of the equipment and relevant circuit diagrams, taking
# T z3 n1 i* o! z1 t. Q1 ]6 Pinto account the possibility of disconnection of the supply with any on/off switch in either ' B: A5 E1 H" R7 A$ x- R, E0 ^
position.
/ p6 h% A, v5 Z0 Y% J; w. VEquipment is considered to comply if any capacitor having a marked or nominal capacitance
; \# c# ^0 S4 k/ ^, F7 ]6 wexceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge
$ B- C1 |/ s0 ^% g0 H9 W1 h/ c) sresulting in a time constant not exceeding:- Z" e* {" @* D J
− 1 s for PLUGGABLE EQUIPMENT TYPE A; and
: w9 ]% G9 S! g& h− 10 s for PLUGGABLE EQUIPMENT TYPE B. ( x0 p# V5 q5 t
The relevant time constant is the product of the effective capacitance in microfarads and the
# [" Z( b3 l( T+ Seffective discharge resistance in megohms. If it is difficult to determine the effective 1 G4 |9 [$ ? l$ C2 M, G$ E
capacitance and resistance values, a measurement of voltage decay at the point of external
' q8 ]8 x# e' W& t' @disconnection can be used. When conducting the voltage decay measurement, the result is
3 ]# T" h" G6 Othe measurement is either made with, or referred to, an instrument having an input impedance 3 a& o2 N, n0 W, R; G6 x
consisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of ' d1 N& x' x& x o$ }
20 pF ±5 pF 25 pF or less. |
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