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那看这一段标准上的列子IEC61131-26 A# m* _& c, s( M0 P
Zone 1: At the field wiring terminals the 1,6 mm from Table 51 dominates the 1,64 mm6 s* r, E) F7 r# U; ~( t
creepage distance from Table 54. Therefore, a minimum of 1,6 mm clearance and creepage* i; T9 u( [" S5 g# y& e+ F
distance shall be maintained. Beyond field wiring terminals, basic clearances shall be 1,50( z5 l! H5 u. l; L0 k/ d& {, {, i9 p B
mm or greater, according to Table 49, and creepage distances shall be 1,64 mm or greater,
2 I l3 Y9 E( \2 f* Naccording to Table 54.
: x; u- _/ f% O1 dZone 2: On a printed circuit board a minimum basic clearance of 2,25 mm shall be maintained i% e2 ]# Z& ~
according to Table 49 for the working voltage of 450 V and a creepage of 2,85 mm from
0 }; J% p; R& O7 }9 PTable 56 because of the 1 600 V recurring peak。, U/ u2 d3 p) ]: t5 A h7 U5 A/ C9 ?
At the isolation boundary to the SELV circuit the 2,3 mm clearance from Table 50 dominates
3 Y* W0 G6 m" K% [% c+ bthe 1,73 mm creepage calculated by multiplying the interpolated value of 0,87 from Table 55
. T& N7 y3 y3 o! C+ Pby 2 according to 11.4.4 for double insulation. Therefore, a 2,3 mm minimum clearance and
@# n/ e7 p3 s0 ]& j1 Z8 u! Vcreepage distance shall be maintained. t6 `* \& c$ E! g+ C
最后在取SELV的爬电距离时,选择了系统电压值。 |
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