Views: 3 Author: Site Editor Publish Time: 2022-05-25 Origin: Site
Metallized film capacitors are capacitors made of organic plastic film as the medium and metallized film as electrodes, which are made by winding (except for the laminated structure). The films used in metallized film capacitors are polyethylene, PP, polycarbonate, etc., in addition to the winding type, there are also laminated types. Among them, polyester film factory media and PP film media are widely used.
The metallized film capacitor is to evaporate a layer of metal film on the surface of the polyester film instead of the metal foil as the electrode, because the thickness of the metallized film layer is much smaller than the thickness of the metal foil.Therefore, the volume after winding is also much smaller than that of the metal foil capacitor. The advantage of metallized film capacitors is the "self-healing" feature.
The so-called self-healing property is that if the film dielectric has a defect at a certain point and a breakdown short circuit occurs under the action of overvoltage,and breakdown point of metallized layer can be melt in arc under the action of instantaneous evaporation and form a small metal free zone,the two pole pieces of the capacitor are made non-conductive to each other again and can still continue to work, thus enhancing the reliability of the capacitor's operation.
This type of capacitor with metallized film has a so-called self-healing effect, that is, if a small part of the electrode is short-circuited due to the fragile electrical interface, the electrode metal around the short-circuit part will be caused by the capacitor at that time. The electrostatic energy or short-circuit current caused a large area of melting and evaporation to restore non-conductivity, so that the capacitor can restore the function of the capacitor.