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标题: DSH 394A Touch current for equipment having multiple supplies supplying power [打印本页]
作者: 小米    时间: 2012-11-6 17:06
标题: DSH 394A Touch current for equipment having multiple supplies supplying power
DSH 394A: s' {% V. D1 G. W; H( f$ H3 G, n

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8 Q9 \) G0 W5 Y2 ^		Touch current for equipment having multiple supplies supplying power simultaneously( j# O6 ~% }9 H  h4 T, H7 ]+ \9 {
5.1.2, last paragraph / 5.14 r! e& b' U7 _8 l+ v, h+ F" n6 n  w
60950-1(ed.1) & 60950(ed.3)! n3 p7 l; y$ n* c* s) f4 f
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Standard(s):" ^( H: p, r7 ?( Z
IEC 60950 (1999) 3rd Ed.
/ S( ~+ L6 {; J- u0 MIEC 60950-1 (2001) 1st ed.
9 E+ E1 w0 \2 M8 K( y1 ^Sub clause(s):8 n* M  _  j2 r: l6 q* Y4 \( a3 D2 p. S
5.1.2, last paragraph) Y5 Z. f7 i" J
5.1
8 K& d7 x/ l" Z) ^9 Y7 k# [Sheet n°: 394A- W  x9 f" M- a% x: I. L) ^
Subject:5 f5 R2 V: a+ `4 Y
TOUCH CURRENT for equipment
+ e; [8 i  ?# `& K0 phaving multiple supplies supplying% m9 e' H" c  R  w
power simultaneously) D. C, L- D4 W( \3 L
Key words:
1 s2 U5 \. N9 ?# G5 Z' D; v' ~- TOUCH CURRENT for equipment
; i/ \/ n' S  u8 u$ \with multiple supplies
3 A! X4 ^  j8 w  xDecision taken at the 41st+ f0 z# E+ P; q8 Y( i9 B' U' w
CTL meeting 2004. This  d- Y" T2 A  B% \3 ?( D
decision replaces n. 394* C) |: S# e3 a. z/ S! ?
taken at the 39th CTL
! g- a1 |; w4 Rmeeting 2002
  w  x* z% z( W! {# SQuestion:, q3 d* l  Y5 v: ^) t
1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the% h4 d$ e+ s. T0 _" `
PROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT- c+ G9 @$ i0 [3 t
or PLUGGABLE TYPE B connection to the supply and meet 5.1.7?! N3 z; t$ L+ q6 K8 `* P( x
2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT
; t3 C; t- v5 R' F9 C+ oexceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
! J2 V  I+ c- hSUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a
3 W, P4 |2 B( z  i- hreliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY
1 U  K* l9 d, ]  g% T8 `6 hconnected EUT?. {& x! l$ o7 a' H
Rationale:  ]# g& p; J! K3 i" E
PLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if( w5 ~; X! Q$ k8 i+ p
the TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY' w# z; _% g# r: {* r8 h
connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may  E7 u3 X0 w" n( r3 [6 Z
not be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all/ q6 ?$ V% W/ n- ~
such socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE
9 H+ G9 {+ H& T7 f4 ^1 X: s7 vCONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or- D  ?6 i) U/ Z3 ~# g4 }7 W
have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be' l, |4 P, p5 c* w) y6 s
PERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to+ e; J7 l) f5 W5 Q
comply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
5 G5 C; H  w2 P# i9 L' @and a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection
( n% G0 }8 }( m  b" {- ebefore disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection) w: G9 {: e* x0 W) \% I# n
Decision:( W* k7 ]% l; V( l9 ]
See copy of the CDV for IEC 60950-1 2nd edition on Page 2
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2 {$ T5 L+ {8 c$ K, v[attach]77167[/attach]
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