What a Self-elevate capacitor used for????

[ZengLei]

What's the effect of a Self-elevate capacitor or a Self-elevate circuit ?????
In what condition we should use a Self-elevate circuit???

thanks~~~~~~~

 

[Meridian]

What's the effect of a Self-elevate capacitor or a Self-elevate circuit ?????
In what condition we should use a Self-elevate circuit???

thanks~~~~~~~

I don't understand your question, perhaps you can be more specific.
Where did you get the term 'self-elevate'?????

 

[dolphin42]

Let's assume the poster means "self healing"?



Self Healing Property

The self-healing feature of the metallized capacitor offers a distinct advantage over the non-metallized unit. This self-healing feature is a result of the extreme thinness of the metallized electrode material. Whenever a flaw or weak spot in the dielectric results in a short condition, the stored electrons in the capacitor and the associated circuitry will immediately avalanche and cross at the shorted point. The electron density concentration results in an extremely high current condition which in turn provides sufficient energy in the form of heat to vaporize the thin metallic electrode. The vaporized electrode forms a fairly concentric pattern away from the point of the short. As a result of the vaporization, the short condition is removed and the capacitor is again operational. This is known as a "clearing" which is the self-healing process.

To illustrate this process imagine a greatly enlarged section of a capacitor containing an extremely thin spot in one of the dielectric sheets. Possibly, it is the result of two valleys on opposite sides of the dielectric surfaces coinciding at a point. This is an example of the distance between the electrodes at a thin spot that is not capable of withstanding the voltage stresses - thus a short develops. The "self-healing" or "clearing" action vaporizes the metal films; therefore, the effective distance between the electrodes increases, the short is removed, and the capacitor is again a "good" unit.

There are two factors to be considered relative to a self-healing or clearing action. There must be sufficient energy present to accomplish this clearing action and during the process, the circuit will experience a small, short-duration, transient voltage drop.

Self healing caps are a good choice for low capacitance applications in high energy/high voltage circuits.

Note that for circuits where failure would expose humans to shock, the "double dielectric AC Line rated cap (called X2 cap, often) is recommended.