|
楼主 |
发表于 2010-1-6 09:40
|
显示全部楼层
引用第1楼yanfenghmm于2010-01-06 09:17发表的  :( `# Z, z6 s/ f! R. W$ ]5 n* k" T
标准应该有具体要求吧。 文字的要求有时是含混不清的,要看读者的理解呀+ K" l M o i- b2 @4 b1 @" G
下面是table 4:
, I3 Y6 J& [( c2 p2 t .7 ^* |5 c0 V$ m& f7 U6 v
+ [6 f# m O3 I( [2 i# \: k+ w
6.7.1.1 CLEARANCES/ q$ j s5 B; G1 A" U
CLEARANCES are specified to withstand the maximum transient overvoltage that can be$ Y2 O. \ y& H
present on the circuit, either as a result of an external event (such as a lightning strike, or a
. v* {- p# B! X/ u/ y7 Y; Tswitching transient), or as the result of the operation of the equipment. If transient0 G# h$ [9 X8 v* X8 o$ I# ]
overvoltages cannot occur, CLEARANCES are based on the maximum WORKING VOLTAGE.4 o) x% z( S+ S8 ^) {% [7 S& U
The value for CLEARANCE depends on6 G" M/ U6 ]' D
a) the type of insulation (basic insulation, reinforced insulation, etc.);
; y, N5 o- _$ T; G7 |: M9 V) c7 X1 \0 kb) the POLLUTION degree of the micro-environment of the CLEARANCE.
3 Q! q% m. H0 R% A: S; H7 A0 H
3 @% Y$ w5 v* H7 i+ N# D6.7.1.2 CREEPAGE DISTANCES
9 b4 N9 `4 C b. H# `) QFor CREEPAGE DISTANCES between two circuits, the actual WORKING VOLTAGE which stresses& M9 q; Z0 c& Y1 _( h! A. G2 [
the insulation between the circuits shall be used. Linear interpolation of CREEPAGE DISTANCE is3 I( k: J8 U- z0 v( M2 n- v7 @
permissible. CREEPAGE DISTANCE shall always be at least as large as the value specified for
( I' a C9 K- B6 r& i$ m% K4 CCLEARANCE.) p6 z: e/ T3 X) v, m1 x
$ B* \$ U- x9 F- o一般而言电气间隙被设计为耐受最高瞬时过电压,经常会考虑工作电压峰值带来的影响;而爬电距离被认为是耐受工作电压有效值的。: r d/ e9 G: f/ x% n7 H
从上面两大块文字中,该标准中6.7.1.1看不出电气间隙要考虑工作电压(peak or rms)的要求,但6.7.1.2爬电距离明确说明要考虑工作电压。而table 4中第一列表头只写了"Voltage line-toneutral
% x* \5 S) Y. _. Xa.c. r.m.s. or d.c.",也没有提"working voltage"。所以实际查表时我就犯难了,到底如何操作呢,请高手指教! |
本帖子中包含更多资源
您需要 登录 才可以下载或查看,没有账号?注册安规
x
|