Views: 1 Author: Site Editor Publish Time: 2018-05-25 Origin: Site
1, advantages: Polyester capacitance precision, loss angle, insulation resistance, temperature characteristics, reliability and adaptation to the environment and other indicators are superior to electrolytic capacitors, porcelain capacitors two kinds of capacitance.
2, disadvantages: polyester capacitor capacity price ratio and capacity volume ratio are greater than the above two capacitors.
3, use: polyester capacitor used in various DC or medium low frequency pulsating circuits. It is suitable to be used as a bypass capacitor.
Theoretically, assuming capacitance is pure capacitance, the greater the capacitance, the smaller the impedance, and the higher the frequency of passing through. But in fact, more than 1 F capacitors are mostly electrolytic capacitors and have large inductance components, so the impedance will increase when the frequency is high. Sometimes there is a larger capacitance than the electrolytic capacitor in parallel with a small capacitance. At this time, the large capacitance is filtered at low frequency and the small capacitance is filtered at high frequency. The role of the capacitor is through AC DC isolation, through high frequency resistance low frequency. The higher the capacitance is, the easier it is to pass the high frequency. Specifically used in filtering, large capacitance (1000 F) filter low frequency, small capacitance (20pF) filter high frequency. Some netizens have likened the filter capacitor to the "pond". Because the voltage at both ends of the capacitor does not change, it can be seen that the higher the frequency of the signal, the greater the attenuation, and the more image the capacitance is like a pond, which will not cause the change of water due to the addition or evaporation of several drops of water. It transforms the change of voltage into the change of current. The higher the frequency, the greater the peak current, thus buffering the voltage. Filtering is the process of charging and discharging.
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