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The Absorption Coefficient Of The Film Capacitance
Jan 17, 2019

Film capacitor is a kind of metal foil as an electrode, and polyethyl ester, polypropylene, polystyrene or polycarbonate and other plastic film, from the end of the overlap, wound into a cylindrical structure of capacitors. But the polypropylene film capacitor its absorption coefficient is very small, the capacity and the loss Angle tangent tg sigma with the temperature change is very small, the dielectric strength increases with the temperature rise, this is one of his characteristics, this is other capacitor is difficult to have. 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, which is related to the dielectric, dielectric polarization and the phenomenon of capacitor absorption. This coefficient is not the same, different manufacturers, different model batches will be different, or even the same manufacturer model batch produced by each film capacitor 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 will be and the faster the capacitor will charge and discharge. In an absolutely ideal state, if the absorption coefficient is 0, the dielectric (i.e. the insulator) will have no polarization phenomenon under the action of external electric field, the dielectric surface will have no traction and binding force on the charge, and the capacitor charge and discharge response will have no lag. Of course, this would be ideal, but the current technology is not yet available.

If the absorption coefficient is too large, the capacitor charge and discharge response lag will be serious, the time constant of ultra-low frequency smooth filter will become larger, and after the zero point of dc amplifier is disturbed, the one-way drift, the ripple of power circuit will increase, and so on, will occur. Therefore, the smaller the absorption coefficient of the film capacitor, the better.