Interpretation of the absorption coefficient of film capacitors

Film capacitors are everywhere in our lives and are widely used, such as our common air conditioners, refrigerators, washing machines, water heaters, etc. Today, I will show you how film capacitors work, what the absorption coefficient of film capacitors is, and what the role of the absorption coefficient of film capacitors is and what abnormalities may occur. Let’s follow the editor’s progress to learn more!

Film capacitors are capacitors that use metal foil as electrodes, overlap it with plastic films such as polyethylene, polypropylene, polystyrene or polycarbonate at both ends, and then roll it into a cylindrical structure.The polypropylene film capacitor has a very small absorption coefficient, and its capacity and loss tangent tg σ change very little with temperature. Its dielectric strength increases with rising temperature. This is a characteristic that other capacitors do not have.So what is its absorption coefficient? This is the value used to describe the dielectric absorption phenomenon of film capacitors. We call it the absorption coefficient. It is related to the dielectric, the polarization of the dielectric and the absorption phenomenon of the capacitor.This coefficient is not the same. It will be different for different manufacturers and different model batches. Even every film capacitor produced by the same manufacturer and model batch may be different.

The dielectric absorption effect of the film capacitor determines the low-frequency characteristics of the capacitor. The smaller the absorption coefficient, the better the film capacitor is and the faster the capacitor charges and discharges.Under absolutely ideal conditions, if the absorption coefficient can be 0, the dielectric (i.e. insulator) will not be polarized under the action of an external electric field, the dielectric surface will have no pulling force on the charge, and the capacitor charging and discharging response will have no lag.Of course, this is an ideal situation, and it cannot be achieved with current technology.

If the absorption coefficient is too large, the capacitor charge and discharge response will be severely delayed, the time constant of the ultra-low frequency smoothing filter will become larger, the DC amplifier zero point will be disturbed, unidirectional drift will occur, the power supply circuit ripple will increase, etc. Therefore, the absorption coefficient of the film capacitor should be as small as possible.

After reading this article, you should have some understanding of what the absorption coefficient of film capacitors is. If you have any technical questions, please contact us and we will be happy to answer them for you.