The Metalized Polypropylene Film means that the capacitor with electrodes formed by vacuum evaporation of metal deposited directly onto the dielectric strength of polypropylene film was put to very effective use to produce a very compact and the light weight construction of capacitor. The construction of this type of capacitor is like having one sheet of Polypropylene Film in which an upper part is metalized with aluminum (Al) or zinc (Zn) with standard thickness having 0.2μm. Once we made a kind of sheet then it is wound on mandrill with specified number of layers as per calculation. After that, for outer connection purpose like making series or parallel connection we spread the zinc (Zn) spray on the top of the winding as well as bottom of the winding.
Due to this type of construction there is no possibility of occurrence of air packets or bubbles or moisture content in between the conducting & non-conducting material. That is why in this case there is no requirement of vacuum impregnation process.
The self-healing property is the main property of Metalized polypropylene film. With the help of Metalized polypropylene film in capacitor, the arc discharge extinguishes without causing large damage. If defect area is small then capacitor will be in service without any interruption and self-healing property of Metalized polypropylene film is itself gives small area deflects. Such Capacitors can use under very high electric stress, which allows to store a large amount of energy in small volume.
On the other hand, when there is a possibility of rapidly in creasing in voltage, current and temperature beyond it scerta in limit then insulation of that capacitor may get break down or some times degraded. Due to this internal short circuit, this part is of no use. But capacitor is heated and continually operated with slightly low capacitance. Self-healing is convenient feature for capacitor. But if the capacitors frequently operate at higher voltage, current, or temperature.
Then it will reduce its capacitance more rapidly and finally it affects on frequency of that filter network.