|
|
It comes from UL 746C
3 J% c) r: [* i+ O" {8 C( T& K/ Q& T* z
) ^4 \4 n. L& S* C2 T* }3 b* I, m3 [! _# Y6 O/ T3 o( j
55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical. T/ \& a; N/ T7 X
abuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall
# Z! z# ~1 t9 [& z( pcomply with the requirements for resistance to impact and drop as indicated below, and: G- @2 w- Q8 s( _4 ^
the requirements for mold stress release distortion, in the Standard for Polymeric Materials
3 }% w N" ?% ^( y! B6 Q* `! u- Use in Electrical Equipment Evaluations, UL 746C.9 b Q2 Y. f+ R' u: v. u
5 u) F# n8 k5 `In UL 746C, the standards says
: f" ?- K- ?5 U* f
" ^) K" I- b1 A$ l: G, X8 d6 l58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in
9 Q7 F, r; N: \& U$ yTable 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during2 L0 g; L& X# @. N' k1 [) B
intended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter,
/ g5 w4 n. p: yand weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown8 Q8 O1 Z" M+ z6 N9 h+ O
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two4 s2 J; G( x# t" ^' P# b: R$ T/ R
impacts. For surfaces other than the top on an enclosure, either the sample could be supported on the7 @4 B6 ~0 O# I& e: u
side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
' \9 g( `. K" L% j# Q" u: y# oand swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the- n& s6 m6 n( f2 Z$ k" N, Y5 X
surface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests, M$ \; G- @" C- T Z: n6 N: a
in the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
( y; V' x" q9 q* n ?9 ~7 Z) |in accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the
! [( A8 `' n8 \; Esequences represented in Figure 58.1. |
|
/2 
|关于安规|小黑屋|安规QQ群|Archiver|手机版|安规网
( 粤ICP13023453-10 ) 
窥视卡
雷达卡
发表于 2008-8-18 11:15
提升卡
置顶卡
沉默卡
喧嚣卡
变色卡
抢沙发
千斤顶
显身卡
发表于 2008-8-18 11:50
楼主
[s:87]7 [+ D0 O3 K- K) J$ c
