Relationship between voltage and pressure and film capacitance self-healing

The effect of applied voltage on the self-healing properties of the film capacitor: in order to achieve self-healing, there must be a certain amount of action at the surrounding breakdown point to form a solid-opening zone where the metal is removed, but if the amount of release is too much, the adjacent medium will be It will be damaged and cause new breakdown. If it is developed, it will cause repeated breakdown of the medium to cause the medium to burn and self-heal at the point of breakdown. It can be seen that in order to obtain a sufficient self-healing halo zone and the adjacent medium is not damaged, the self-healing discharge amount must be drawn within a certain range. The amount of self-healing area dissipated is an important parameter affecting self-healing performance.

The amount of self-healing released by external pressure has a lot to do with stress. The self-healing point pressure increases the insulation and is easy to recover. The radius of the self-healing halo area formed is small, and the amount of release is correspondingly reduced. When dissecting the capacitor with the test voltage, it can be seen that the self-healing halo area is larger in the looser outer layer of the film capacitor, and the inner layer is tightly wound, and the area is smaller. Generally, the outer halo area is about 2 to 10 times larger than the inner halo area.

The self-healing of the film capacitor means that it is realized under certain conditions, and the film capacitor loses its self-healing performance beyond a certain limit. When designing and testing the film capacitor, it should be carried out under the condition as far as possible, that is, the pulse current introduced during the dielectric breakdown is small, and the amount of release is small, so that the damage of the medium near the breakdown point is also small from the capacitor structure. The length of the component plates and the increase in the width of the plates are advantageous for self-healing.