Image courtesy of KYOCERA AVX. Metallized film capacitors exhibit a self-healing property that significantly improves their lifetime reliability characteristics. Figure 4 depicts the basic process wherein a dielectric defect results in a high current, high-temperature short circuit that quickly demetallizes the surrounding area.
Unfortunately, this mechanism can be dificult to control, and in the worst case, a run-away process can result, causing the destruction of the entire capacitor in short order. To avoid this, KYOCERA AVX developed a controlled self-healing process in 1974 based on the segmentation of overall capacitance into elementary cells protected by fuse gates.
RP serves as a valuable tool for evaluating the safety of MFCs with an unknown SH history, contributing to the assessment of their reliability. Metallized film capacitors (MFCs) are known for their self-healing (SH) properties, enabling efficient and reliable operation, even under challenging conditions.
Provided by the Springer Nature SharedIt content-sharing initiative Policies and ethics Metalized film capacitors (MFC) are widely applied in power system, military weapons and railway traffics, etc. The lifetime of MFC is closely related to the self-healing (SH) process, which causes the loss of electrode area and thus leads to the capacitance...
To achieve such performances, metalized film capacitors (MFC) are adopted. Comparing with conventional liquid impregnant capacitors, the high energy density of MFCs is derived from the self-healing properties of metalized film.
Figure 1: Conventional aluminum electrolytic capacitor. Image courtesy of KYOCERA AVX. On the other hand, metal film capacitors rely on a metallized dielectric film to form the capacitive structure. Many film materials are available - most commonly, polypropylene and polyester.