|

楼主 |
发表于 2011-3-10 16:37
|
显示全部楼层
那看这一段标准上的列子IEC61131-2
, W! _1 G% G1 E& Q$ l/ ~Zone 1: At the field wiring terminals the 1,6 mm from Table 51 dominates the 1,64 mm$ i8 S8 a+ S, K l0 d; V9 K
creepage distance from Table 54. Therefore, a minimum of 1,6 mm clearance and creepage
0 ?+ H. X# ~7 Y" Y5 g4 P# K: qdistance shall be maintained. Beyond field wiring terminals, basic clearances shall be 1,50
, Z X1 q+ v. q+ i u* y& nmm or greater, according to Table 49, and creepage distances shall be 1,64 mm or greater,1 K8 o: O' K7 s, Z" n+ v
according to Table 54.6 c; c P& t% O7 o/ g1 G( n
Zone 2: On a printed circuit board a minimum basic clearance of 2,25 mm shall be maintained
, e' e+ b: z2 g' K% h) h* Z) t& N- Gaccording to Table 49 for the working voltage of 450 V and a creepage of 2,85 mm from; _8 |7 \9 E* U+ x4 ?% T
Table 56 because of the 1 600 V recurring peak。) D2 Y/ G$ D D7 }' B" R
At the isolation boundary to the SELV circuit the 2,3 mm clearance from Table 50 dominates
/ ]% x- X6 u5 d; b4 rthe 1,73 mm creepage calculated by multiplying the interpolated value of 0,87 from Table 55
4 g7 u* w' H: l8 uby 2 according to 11.4.4 for double insulation. Therefore, a 2,3 mm minimum clearance and
; g: Q3 Z( R' ~ Qcreepage distance shall be maintained.
' N6 ?7 `3 t6 R6 L; \最后在取SELV的爬电距离时,选择了系统电压值。 |
|