Self-healing process of metallized film capacitors

A metallized film type capacitor has a self-healing property. That is to say, if a small part of the electrode is short-circuited due to the fragile electrical boundary, the electrode metal around the short-circuited part will be restored due to the amount of static electricity or short-circuit current carried by the capacitor at the time, causing a larger area of melting and evaporation. Insulation allows metallized film capacitors to restore the capacitor again.

Self-healing process of metallized film capacitors:

1. The breakdown capacitor occurs under the applied voltage due to the presence of internal impurities or air gaps causing breakdown to form a current path.

2. A relatively short pulse current flows through the leading edge of the metal layer in a small area near the current sinking, causing the current on the metal layer near the breakdown point to rise, which is inversely proportional to the distance from the breakdown point. At a certain instant, the temperature of the metal layer reaches its melting point within the radius Rt, so the metal melts to generate an electric current. The current at this time causes the amount of metallized film capacitors to be released, the local temperature rises, and the pressure becomes large.

3. With the progress of the discharge, the metal layer will evaporate within the radius of Rt, and even sneeze may occur when the radius is increased: the arc is broken at the same time as the radius of the region is increased, and the metal is blown and then oxidized and ice-cold after the electric pull is broken. The final conductive path is terminated, and the surface of the medium is formed with a circular insulation area with no metal layer at the breakdown point.