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楼主 |
发表于 2009-8-1 10:33:26
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台式机的电源输入端有 X Y电容，如果不接地，外壳容易因为Y电容的影响而带电，手摸会有发涩的感觉。
如果要用这种电源调试电路板，电路板也会带上电，可能用手一碰哪里，就把芯片烧了
如果用3座插排，可靠接地，是没有问题的。
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哦，谢谢啦，这样一解释我就心里有底了。看来只要接地可靠，这个方法还是可行的。等做成后给大家上图。
另转贴一片网上查到的XY电容的解释：
找一块电源仔细看一下，在电源部分中，跨接L-N之间的小方块（单位是μF）电容就是X电容，通常在是电源入口的第一个；
同样，在电源部分的跨接L-PE和N-PE之间的蓝色的安规电容（单位pF）就是Y电容，通常是成对出现的。
或者你可以形象的看，X电容具有2个输入端，2个输出端，很象X；Y电容具有一个输入端，一个输出端以及一个公共的大地，很象一个Y
没有什么概念的，一个在差模回路上，一个在共模回路上，X、Y的名称纯粹是一个称呼，就象是X和Y轴一样
X电容主要用于流电源线路中，此时当电容失时不致产生线间放电。X电容器的测试条件是：在交流电压的有效值*1.5的电压下工作100Hour；再加上1KV的高压测试。
Y电容器在一旦失效会导致放电危险（尤其是对外壳）时是强制使用的。Y类型电容器的测试条件是：在交流电压的有效值*1.7的电压下工作100Hour，加上2KV高压测试。如果电容器用于不接地的II类产品中，则要增加至4KV。
要想详细的知道什么是X电容,什么是Y电容最好的办法打个电话给你的电容供应商就可以了解的很详细清楚. X,Y电容主要是安规要求具体请可以查IEC60950有说明.
X–capacitors are suitable to use in situations where failure of the capacitors would not lead to the danger of an electrical shock. They are typically connected across the AC lines for differential mode suppression.
According to EN 132400, X–capacitors are divided into 3 sub classes, depending on the peak impulse voltage to which they are exposed during operation. This kind of impulse can be caused by lightning in overhead cable, switching surges in neighboring equipment or in the device in which the capacitor is being used to suppress interference.
Typically, X2–capacitors are use for MC3337X based SMPS, X3–capacitors are seldom used. X1–capacitor can be used but come at a higher cost.
Y–Capacitor
Y–capacitors are intended for use where the failure of the capacitor could result in a dangerous electrical shock. They have a higher electrical and mechanical reliability intended to eliminate the possibility of short circuits in the capacitor. The value of Y–capacitor is limited by safety regulations.
Y–capacitors are usually connected from the AC lines or bridge rectifier output to the secondary, chassis, shield, or earth ground.
According to EN 132400, Y–capacitors are divided into the following sub classes:
Sub-Class Peak Pulse Voltage Vp in Operation Application
X1 2.5kv<Vp≤4kv For high peak voltage
X2 Vp≤2.5kv General purpose
X3 Vp≤1.2kv General purpose
Sub-class Type of bridge insulation Rated AC voltage Peak value of surge voltage Vp
Y1 Double or reinforced insulation Vr≤250V 8KV
Y2 Basic or supplementary insulation 150v≤Vr≤250V 5KV
Y3 Basic or supplementary insulation 150v≤Vr≤250V No test
Y4 Basic or supplementary insulation Vr≤250V 2.5KV |
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发表于 2009-7-31 15:18:49
