Views: 3 Author: Site Editor Publish Time: 2022-04-06 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.
Metallized film capacitors are made by evaporating a layer of metal film on the surface of polyester film instead of metal foil as electrodes， because the thickness of the metallized film layer is much smaller than that of the metal foil, 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, the metallization layer of the breakdown point can be melted and evaporated instantaneously under the action of the arc to form a small metal-free area, so that the two pole pieces of the capacitor can be re-insulated from each other and can still continue to work.Therefore, the reliability of the capacitor operation is enhanced.
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 will cause a larger area of melting and evaporation to restore the insulation, so that the capacitor can resume the function of the capacitor.