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没有说要在故障情况下（open R1）. / R) u% N$ ?; v& U3 M" t/ @
2.1.1.7 Discharge of capacitors in equipment
3 o4 |& [) t* q$ j# i3 pEquipment shall be so designed that, at an OPERATOR-accessible external point of : o: g* O( }* T, B
disconnection of a MAINS SUPPLY, the risk of electric shock from stored charge on capacitors
; S7 h ], m) Z7 Q2 H6 X& ?connected in the equipment is reduced. No test for shock hazard is required unless the
/ f/ C7 }# c! L# h, d: M0 Dnominal voltage of the MAINS SUPPLY exceeds 42,4V peak or 60V d.c. * P$ u- p& F8 E* C* b6 e- [- O9 f
Compliance is checked by inspection of the equipment and relevant circuit diagrams, taking 3 J G2 N/ G5 @1 c: s% B
into account the possibility of disconnection of the supply with any on/off switch in either
* Z1 ~2 {! s, j/ n5 gposition.
( {; X( v3 m' Y0 s iEquipment is considered to comply if any capacitor having a marked or nominal capacitance % u2 T( [0 ~6 d3 Z3 F
exceeding 0,1 µF and in a circuit connected to the MAINS SUPPLY has a means of discharge , c( `! n* o7 N7 S+ G) }# V
resulting in a time constant not exceeding:
) M0 [+ }" q1 \. o− 1 s for PLUGGABLE EQUIPMENT TYPE A; and
" ^ g9 n' m2 l* V& \) A− 10 s for PLUGGABLE EQUIPMENT TYPE B.
- b3 t; l. H- H& X5 VThe relevant time constant is the product of the effective capacitance in microfarads and the * u6 T0 D- D8 J, M
effective discharge resistance in megohms. If it is difficult to determine the effective " J1 B7 s. k4 c* t* b9 |6 v% X
capacitance and resistance values, a measurement of voltage decay at the point of external 2 `$ I$ |. H1 R' y: B6 U2 D. U: F
disconnection can be used. When conducting the voltage decay measurement, the result is
; B% D, n1 s$ h o' T Qthe measurement is either made with, or referred to, an instrument having an input impedance
6 W3 i. l: w: O8 Pconsisting of a resistance of 100MΩ ±5 MΩ in parallel with an input capacitance of
* l+ x; Q7 y7 O/ }20 pF ±5 pF 25 pF or less. |
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发表于 2014-5-16 18:02
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