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|  DSH 595/ y2 N+ E/ I% Z1 R
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| Requirement for the screws fixing internal parts
, x1 {3 s0 X2 u3 Z0 g+ Y | 17.3
' [6 j5 z4 \0 S! b | 60065(ed.6) & 60065(ed.7)
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Standard(s): w4 V5 D. q! t+ Y% I$ O
IEC 60065 : 1998 6th edition
2 \, {; D, l* c5 P$ y2 E; qIEC 60065 : 2001 7th edition
- O& B# M) U% M8 Q2 eSub clause(s):' a6 b! |4 s5 |/ d. R7 ^
17.3
9 {4 t K4 Y, L% i: V: Q. M6 nSheet n., D9 z$ s% D3 K
DSH 595% k/ g) M2 Z @
Subject:
* R0 }# I4 S0 T6 {% aRequirement for the screws fixing6 D @' B' A/ E1 n# d& y
internal parts- u2 R' h4 \, r
Key words:
* E; e9 z7 u2 R$ g; O) n' B- Screws0 m( f$ t( `1 y
- Fixing internal parts
- R1 S' P- h; ~7 x. p: uDecision approved
% e/ f( \5 ^& A4 |during the 44th CTL
( r5 G8 K1 }6 J9 [" l% M# Z1 Hmeeting 2007
$ n( M- }$ f. k) f9 H3 |7 X; YQuestion: Should those screws, fixing internal parts, needed to be replaced for a service be captive or
! k5 }4 Y! r/ O, wcomply with the insulation distance stated in clause 13 when replaced by screws having the same nominal5 N% ]( q7 c9 P; n+ r: g
diameter with a length of 10 times their nominal diameter? In the latter case, what insulation is required
# N1 V8 j% o/ q/ v4 n6 n) ?* Y. z" Zbetween the replaced screws and hazardous live parts?9 A, h! ~) v, O3 Q% n# O! U
- Situation
3 E8 t& A1 o. e- There is an amplifier which has an internal SMPS board encased by a metal enclosure.
6 d. O) q) R9 S- u* y% @9 ~- The screws fixing the internal box should be unscrewed to get serviced.4 J: T; V: c! i8 X. O+ {2 o4 k- l y
- The screws are inserted from an exterior side or bottom of the amplifier but not fixing the cover of the, r$ H% M/ E0 O6 ]$ o7 B* z
amplifier.- j6 L" U! b' H( g& F7 H
- The screws are not captive but don't comply with the insulation distance stated in clause 13 when replaced by: V" {: H6 G: ^/ w6 Z3 h
other screws having the same nominal diameter with a length of 10 times their nominal diameter.6 a& z# J# n, F8 V
Decision
8 Z0 w3 e; K; Y" ]It's not acceptable. In case of a PCB fixed by just screws without any enclosure, it's acceptable because the
, M, j! L1 p$ e. V, _service personnel can make sure that the screws are the right screws during a service. However, in case of the
. q- B+ v! b$ d8 S& p+ P$ iabove SMPS board encased by a metal enclosure, it's not acceptable because the service personnel can't know6 J1 m6 ^5 P4 G: m
whether the screws are the right screws or not during a service due to the internal metal enclosure.# y4 _: U, Q, F P( R
In the above case reinforced insulation is required because after the screws are replaced the amplifier can be, M1 Y; Q- i- G7 ~0 m
used without any malfunction./ f1 e1 F6 [; H
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发表于 2012-11-8 17:17
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