6.8UF/250V电解电容

公司名字:东莞市科尼盛电子有限公司

英文名: Dong Guan Ke Ni Sheng Electronic  CO.,LTD）

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电解电容在电路中的作用

1，滤波作用，在电源电路中，整流电路将交流变成脉动的直流，而在整流电路之后接入一个较大容量的电解电容，利用其充放电特性，使整流后的脉动直流电压变成相对比较稳定的直流电压。在实际中，为了电路各部分供电电压因负载变化而产生变化，所以在电源的输出端及负载的电源输入端一般接有数十至数百微法的电解电容．由于大容量的电解电容一般具有的电感，对高频及脉冲干扰信号不能地滤除，故在其两端并联了一只容量为0.001--0.lpF的电容，以滤除高频及脉冲干扰．
2，耦合作用：在低频信号的传递与放大过程中，为前后两级电路的静态工作点相互影响，常采用电容藕合．为了信号中韵低频分量损失过大，一般总采用容量较大的电解电容。

二、电解电容的判断方法

    电解电容常见的故障有，容量减少，容量消失、击穿短路及漏电，其中容量变化是因电解电容在使用或放置过程中其内部的电解液逐渐干涸引起，而击穿与漏电一般为所加的电压过高或本身质量不佳引起。判断电源电容的好坏一般采用万用表的电阻档进行测量．具体方法为：将电容两管脚短路进行放电，用万用表的黑表笔接电解电容的正。红表笔接负(对指针式万用表，用数字式万用表测量时表笔互调)，正常时表针应先向电阻小的方向摆动，然后逐渐返回直至大处。表针的摆动幅度越大或返回的速度越慢，说明电容的容量越大，反之则说明电容的容量越小．如表针指在中间某处变化，说明此电容漏电，如电阻指示值很小或为，则表明此电容已击穿短路．因万用表使用的电池电压一般很低，所以在测量低耐压的电容时比较准确，而当电容的耐压较高时，打时尽管测量正常，但加上高压时则有可能发生漏电或击穿现象．

三、电解电容的使用注意事项

1、电解电容由于有正负性，因此在电路中使用时不能颠倒联接。在电源电路中，输出正电压时电解电容的正接电源输出端，负接地，输出负电压时则负接输出端，正接地．当电源电路中的滤波电容性接反时，因电容的滤波作用大大降低，一方面引起电源输出电压波动，另一方面又因反向通电使此时相当于一个电阻的电解电容发热．当反向电压过某值时，电容的反向漏电电阻将变得很小，这样通电工作不久，即可使电容因过热而炸裂损坏．
2．加在电解电容两端的电压不能过其允许工作电压，在设计实际电路时应根据具体情况留有的余量，在设计稳压电源的滤波电容时，如果交流电源电压为220~时变压器次级的整流电压可达22V，此时选择耐压为25V的电解电容一般可以满足要求．但是，假如交流电源电压波动很大且有可能上升到250V以上时，选择耐压30V以上的电解电容。
3，电解电容在电路中不应靠近大功率发热元件，以因受热而使电解液加涸．
4、对于有正负性的信号的滤波，可采取两个电解电容同性串联的方法，当作一个无性的电容。Electrolytic capacitors in the circuit in the role of

1, filtering effect, in a power supply circuit, rectifier circuit to the AC into pulsating DC, while in the rectifier circuit after accs to a larger capacity electrolytic capacitor, the charge and discharge characteristics, make rectified pulsating DC voltage into a relatively stable DC voltage.In practice, in order to prevent the each part of the circuit power supply voltage due to the load change and produce change, so the output end of the power supply and the load of the power input end is generally connected with tens to hundreds of micro method for the electrolytic capacitor. Due to the large capacity electrolytic capacitor has certain inductance, high frequency and impulse interference signals can effectively filter therefore, in the parallel connected with both ends of a capacity of 0.001--0.lpF capacitor, to filter out high frequency and pulse interference.

2, coupling effect: in the low frequency signal tranission and the amplification procs, in order to prevent the before and after the two stage circuit static working point of mutual influence, often using capacitive coupling. In order to prevent signal in the rhyme low-frequency loss is too large, generally the larger capacity of electrolytic capacitors.

In two, the judging method of electrolytic capacitor

Electrolytic capacitor common fault, reduced capacity, capacity disappear, short circuit breakdown and leakage, in which capacity change for electrolytic capacitor in use or placed in the procs of its internal electrolyte dry up gradually, and breakdown and leakage for the voltage too high or itself caused by poor quality.Judging power capacitor is generally use a multimeter to measure ristance profile. The concrete method is: will the capacitance of the two pin is shorted to discharge, with a multimeter the black table document connected electrolytic capacitor anode.The red pen is connected with the negative pole (the pointer multimeter, using the dial multimeter measuring pen intermodulation), normal hand shall first apply to all ristance direction swing, then gradually returned to infinite big.Hands swinging larger amplitude or return more slowly, that the capacity of the capacitor is more big, otherwise, the capacity of the capacitor is aller. As hands in somewhere in the middle of no change, the capacitor leakage, such as ristance indicator valu are very all or zero, it indicat that the capacitor has breakdown short circuit for million. Use the table using the battery voltage is generally very low, so the measurement of low voltage capacitor is more accurate, and when the capacitor voltage is high, although measurements of the normal play, but coupled with high prsure is possible leakage or breakdown phenomenon.

Three, note the use of electrolytic capacitor

1, electrolytic capacitors with positive and negative polarity, thus used in the circuit can not be reversed.In a power supply circuit, output positive voltage electrolytic capacitor anode is connected to the power output end, negative ground, output negative voltage output end is negative, positive ground. When the power supply circuit of the filter capacitor polarity reverse connection, due to capacitor filtering effect is greatly reduced, on one hand the power supply output voltage wave, on the other hand, because of the inverse power make it the equivalent of a ristance electrolytic capacitor heating. When the reverse voltage exceeds a certain value, the capacitor leakage ristance will become very all, so the electric work soon, can make the capacitance due to overheat and burst damage.

2 plus in the electrolytic capacitor voltage should not exceed the allowable working voltage, in the dign of practical circuit should be based on specific circumstanc leave some margin, in the dign of regulated power supply filter capacitor, if AC power is 220~ voltage transformer secondary rectifier voltage up to 22V, the selection prsure for 25V electrolytic capacitor can generally be to meet the requirements. However, if AC power supply voltage fluctuation and is likely to rise to more than 250V, the choice of prsure above 30V electrolytic capacitor.

In 3, the electrolytic capacitors in the circuit should not close to the high power heating elements, to prevent the electrolyte accelerated by heat to dry up.

4, the positive and negative polarity signal filtering, can take two electrolytic capacitors homopolar seri method, as a non polar capacitor.