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60950的2.1.1.7写到:
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$ ~6 I6 ~" n1 R8 J' L& iNo test for shock hazard is required unless the nominal voltage of the MAINS SUPPLY exceeds 42,4 V peak or 60 V d.c.
2 ?) h9 |2 V$ m$ U* e就是输入超过SELV的就要去考虑电容放电,这是条件一;- G6 S+ Y) d' Y, j4 d( P9 x4 ^
+ d: |: E5 h* ], F! M% e* PEquipment is considered to comply if any capacitor having a marked or nominal capacitance exceeding 0,1 uF and in circuits connected to the MAINS SUPPLY has a means of discharge resulting in a time constant not exceeding: 1 s for PLUGGABLE EQUIPMENT TYPE A;
3 y. D1 x& c; e5 kNOTE During an interval equal to one time constant, the voltage will have decayed to 37 % of its original value.
3 g+ J) y0 `' r9 Z8 X* m0 W7 z2 [) }2 E条件二,如果输入电容(一般看前面跨接L/N的X电容)超过0.1uF的话,针对PLUGGABLE EQUIPMENT TYPE A(非工业插头)产品,它的放电时间常数不能超过1S;
; u9 {: X2 r' |7 Z% k& y这个放电时间常数计算比较复杂,一般情况都是通过测试去判定,1S内plug端的电压(240VrmsX1.4.1=340Vpeak)下降到初始电压的37%(125.8Vpeak)就pass了。 |
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