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metal oxide varistor (MOV)

Metal Oxide Varistors (MOV) are varistors made of metal oxides such as zinc oxide enriched with bismuth, manganese, cobalt and other metal oxides. The various metal oxides, located as layers between metal plates, form diode junctionsin their grains that allow current to pass in only one direction.

The unstructured diode junctions of metal oxide varistors correspond in their function to those of diodes switched in the opposite direction. When a high voltage is applied to the granular metal oxide, the diode junctions switch in the forward direction and tunnel the electrons across the metal oxide. This allows overvoltages to be dissipated.

Metal oxide varistor for 12 V, photo: Epcos

Metal oxide varistor for 12 V, photo: Epcos

In terms of structure, the metal oxide varistor corresponds to the multilayer varistor and, like the latter, is used to dissipate transient overvoltages caused by electrostatic discharges, for example. These interference peaks are converted into heat dissipation by the metal oxide varistor. Metal oxide varistors can withstand extremely high current surges of several amperes to several tens of thousands of amperes. Metal oxide varistors are available with radial and axial connections and in SMD design.

Englisch: metal oxide varistor - MOV
Updated at: 13.09.2012
#Words: 182
Links: zinc oxide (ZnO), cobalt (Co), diode, current, voltage
Translations: DE

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