DSH 595 Requirement for the screws fixing internal parts

小米

广东安规检测
有限公司提供：

小型摆管淋雨试验机

IPX5X6X7喷水试验机

1000L恒温恒湿箱

各种试验指现货

可程式恒温恒湿试验箱

水平垂直燃烧机

自动卷线器试验机

耐划痕试验机

各种灯头量规现货

灼热丝试验机现货

GB1002插头量规

IPX1-X7淋雨现货

IEC61347/UL935镇流器热试验箱

灯具防风罩

IK冲击试验机

UL498插头插座量规

VDE0620插头插座量规

稳定性试验台

家电温升测试角

针焰试验机现货

热电偶焊机现货

家电125mm试验指

E12灯头量规

无绳壶无绳电熨斗插拔寿命试验机

IEC60335试验指甲

DSH 595 - R1 N; z# \7 A; B % v/ r' q( Q) V( V* f+ S

Requirement for the screws fixing internal parts - }4 y9 |1 x5 B7 w7 g+ q4 v8 R3 z

17.3 ( r" e$ h' K* \6 r! M

60065(ed.6) & 60065(ed.7) 1 U9 j3 \+ t# I

8 z9 \$ z0 p5 _! F% e  fStandard(s):
2 {( |, w7 e( K& ]" GIEC 60065 : 1998 6th edition
IEC 60065 : 2001 7th edition
& D: w$ ~, C' oSub clause(s):
! `- l2 _' E6 f1 S' j, d1 y17.3
Sheet n.
DSH 595
( o; H3 z( c" rSubject:
) Z# a) @6 K9 v. J) d: C* ORequirement for the screws fixing
internal parts
Key words:
- Screws
+ w* O# i4 ?+ p- Fixing internal parts
Decision approved
during the 44th CTL
meeting 2007
1 N* \7 {/ y% vQuestion: Should those screws, fixing internal parts, needed to be replaced for a service be captive or
2 j# ]* y4 _0 Acomply with the insulation distance stated in clause 13 when replaced by screws having the same nominal
# @7 W7 U% a* [3 gdiameter with a length of 10 times their nominal diameter? In the latter case, what insulation is required
  N& F, X$ `* z9 R: Mbetween the replaced screws and hazardous live parts?
( @  r1 d& T  M- Situation
- There is an amplifier which has an internal SMPS board encased by a metal enclosure.
- The screws fixing the internal box should be unscrewed to get serviced.
) `" S" R# w, M0 n0 e7 ^- The screws are inserted from an exterior side or bottom of the amplifier but not fixing the cover of the
" S( C8 S" P0 O5 `7 g, d4 Q7 I% jamplifier.
: \1 ^/ m4 H" ^8 g# c( y: M- The screws are not captive but don't comply with the insulation distance stated in clause 13 when replaced by
% P, N, h: J9 ?5 h' Nother screws having the same nominal diameter with a length of 10 times their nominal diameter.
Decision
It's not acceptable. In case of a PCB fixed by just screws without any enclosure, it's acceptable because the
9 O  s) A) ]: K. Cservice personnel can make sure that the screws are the right screws during a service. However, in case of the
+ R% u1 q0 o$ s+ D. q$ A: `above SMPS board encased by a metal enclosure, it's not acceptable because the service personnel can't know
whether the screws are the right screws or not during a service due to the internal metal enclosure.
In the above case reinforced insulation is required because after the screws are replaced the amplifier can be
used without any malfunction.

# H5 N3 T5 o& F" Y! J0 l