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Electrical breakdown in an electric discharge showing the ribbon-like plasma filaments from a Tesla coil.. In electronics, electrical breakdown or dielectric breakdown is a process that occurs when an electrically insulating material (a dielectric), subjected to a high enough voltage, suddenly becomes a conductor and current flows through it.
Dielectric breakdown due to overvoltage or aging of the dielectric, occurring when breakdown voltage falls below operating voltage. Some types of capacitors "self-heal", as internal arcing vaporizes parts of the electrodes around the failed spot.
The physical mechanism causing breakdown differs in different substances. In a solid, it usually occurs when the electric field becomes strong enough to pull outer valence electrons away from their atoms, so they become mobile. The field strength at which break down occurs is an intrinsic property of the material called its dielectric strength.
Some formulations are ohmic until at least 250 kV/cm (25 MV/m), after which current grows exponentially with field strength before reaching avalanche breakdown; but lead zirconate titanate exhibits time-dependent dielectric breakdown — breakdown may occur under constant-voltage stress after minutes or hours, depending on voltage and ...
Intrinsic breakdown is caused by electrical stress induced defect generation. Extrinsic breakdown is caused by defects induced by the manufacturing process. For Integrated circuits, the time to breakdown is dependent on the thickness of the dielectric (gate oxide) and also on the material type, which is dependent on the manufacturing process node.
A useful macroscopic model that combines an electric field with DLA was developed by Niemeyer, Pietronero, and Weismann in 1984, and is known as the dielectric breakdown model (DBM). [7] Although the electrical breakdown mechanisms of air and PMMA plastic are considerably different, the branching discharges turn out to be related.
For example, for a patient who has had a right sided hip replacement who is scheduled for surgery, the return electrode is placed on the left side of the body on the lateral side of the lower abdomen, which places the return electrode between the location of the metal and the surgical site and on the opposite side from the metal.
The characteristics of the skin are non-linear however. If the voltage is above 450–600 V, then dielectric breakdown of the skin occurs. [21] The protection offered by the skin is lowered by perspiration, and this is accelerated if electricity causes muscles to contract above the let-go threshold for a sustained period of time. [14]