Metalized film capacitors use organic plastic film as the medium and metalized film as the electrode. The capacitor is made by winding. The metalized film capacitors use films such as polyethylene, polypropylene, polycarbonate, etc., except In addition to the winding type, there are also laminated types, among which polyester film media and polypropylene film media are the most widely used.
The role of metalized film capacitors:
Capacitors of this type of metallized film have a self-healing action. It is assumed that when the tiny part of the electrode is short-circuited due to the weak electrolyte, the electrode metal around the short-circuited part will be caused by the static electricity of the capacitor at that time. Energy or short-circuit current, which triggers a larger area of melting and evaporation insulation, so that the capacitor will return to the role of the capacitor.
Features of metalized film capacitors:
Metallized film capacitors are vapor-deposited a layer of metal film on the surface of the polyester film instead of metal foil as the electrode. Because the thickness of the metalized film layer is less than that of the metal foil, the volume after winding is also smaller than that of the metal foil capacitor. a lot of.
The biggest advantage of metallized film capacitors is the self-healing feature. The self-healing feature is that the film dielectric has a short circuit due to a defect at a certain point and a breakdown under the action of overvoltage, and the metallization layer at the breakdown point can be in the arc Under the action, it melts and evaporates instantly to form a small metal-free area, so that the two pole pieces of the capacitor are insulated from each other again and can still continue to work, thus greatly improving the reliability of the capacitor.