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|  DSH 595) d- j) S' W5 H/ ?2 R5 z
5 Q$ t: S. u- x( G% f7 P/ ] | Requirement for the screws fixing internal parts* v( x* f) A8 f0 @( s
| 17.39 i/ _' ^9 }- s4 b
| 60065(ed.6) & 60065(ed.7)$ g* P3 k/ q0 R1 a6 `
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4 n6 |9 ^" q, U8 I) C, S; BStandard(s): P) g" n1 x5 U
IEC 60065 : 1998 6th edition, V; q; `& t: x: p' R
IEC 60065 : 2001 7th edition0 c: J) \% j! y) |
Sub clause(s):
: @; ^$ L6 H9 r$ z5 ~' h, d6 G% ~17.35 l" n0 _: R9 g' T; B$ ~
Sheet n.# E w) G6 s6 C, u' @$ a% _
DSH 595' I5 i# u7 G, \- c
Subject:/ w5 A: B; o# r+ E* [
Requirement for the screws fixing6 \- Y, t9 h( C' V
internal parts
* ?8 s. I7 T' U+ IKey words:
) F. J1 o N4 y1 H+ H- Screws
& }* @1 f) w% \7 Z5 }# r" k- Fixing internal parts9 T9 h, B# q( B q* x4 f, U
Decision approved
* ]) Z) Q, s1 v; v. ^2 X! [during the 44th CTL
, N* f4 h0 [9 J( Q) w$ s; dmeeting 2007
* t G: X( N1 mQuestion: Should those screws, fixing internal parts, needed to be replaced for a service be captive or
7 d) Q: r5 T4 D/ ?8 ncomply with the insulation distance stated in clause 13 when replaced by screws having the same nominal
+ n% c) X- }" D! X odiameter with a length of 10 times their nominal diameter? In the latter case, what insulation is required. N, ]% d. M5 L5 _
between the replaced screws and hazardous live parts?
; a T/ D6 g2 m1 j6 ~( e- T- q- Situation: D& M# z8 j2 F @
- There is an amplifier which has an internal SMPS board encased by a metal enclosure.1 Q) q% ^# U' _- \# |7 L1 L( e
- The screws fixing the internal box should be unscrewed to get serviced., e$ q$ c9 Q2 Q9 t4 e! l$ K
- The screws are inserted from an exterior side or bottom of the amplifier but not fixing the cover of the
3 t# i; j0 M1 H$ Q' `/ Bamplifier.
8 _, ~4 K) t/ L i$ W9 }* ~: G0 B2 q- The screws are not captive but don't comply with the insulation distance stated in clause 13 when replaced by1 D; `% n/ [. A$ e; n; o7 {! V( Y
other screws having the same nominal diameter with a length of 10 times their nominal diameter.# I7 X1 v. G' R" ~3 N
Decision
* i5 u1 r+ n) ^, @It's not acceptable. In case of a PCB fixed by just screws without any enclosure, it's acceptable because the
9 V/ C. [$ l, aservice personnel can make sure that the screws are the right screws during a service. However, in case of the
6 m- N6 p0 Q- @0 y H* Q1 z2 i& ?- Iabove SMPS board encased by a metal enclosure, it's not acceptable because the service personnel can't know. x u; O1 F! b K8 M
whether the screws are the right screws or not during a service due to the internal metal enclosure.6 `* c1 a/ ^3 j) s* w
In the above case reinforced insulation is required because after the screws are replaced the amplifier can be* B: o- a% p4 v2 j# b
used without any malfunction.
$ e7 r C9 b) c2 B# h* }
* d6 m( I E0 @6 \3 p: q/ c) h7 w& `: _; n6 I
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发表于 2012-11-8 17:17
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