To overcome this problem the new technique is employed i.e. To use Metallized Polypropylene Film instead of All Poly propylene Film. The Metalized Polypropylene Film means that the capacitor with electrodes formed by vacuum evaporation ofmetal deposited directly onto the dielectric strength of polypropylene film was put to very effective use to produce avery compact and the light weight construction of capacitor. The construction of this type of capacitor is like havingone sheet of Polypropylene Film in which an upper part ismetalized with aluminum (Al) or zinc (Zn) with standard thickness having 0.2μm. Once we made a kind of sheetthen it is wound on mandrill with specified number of layersas per calculation. After that, for outer connection purpose likemaking 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 inbetween the conducting & non-conducting material. That iswhy 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 Metalize dpoly propylene 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 itscertain 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-healingis 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 itaffects on frequency of that filter network.