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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/03/06 09:55:30」(JST)

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This article is about a concept in electrical engineering. For use in electrochemistry, see overpotential.

Voltage spike.

When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage. The conditions may be hazardous. Depending on its duration, the overvoltage event can be transient—a voltage spike—or permanent, leading to a power surge.

Explanation[edit]

Lack of 3-phase electric system connected by star. If zero breaks off, small-power appliances will be destroyed by overvoltage

Electronic and electrical devices are designed to operate at a certain maximum supply voltage, and considerable damage can be caused by voltage that is higher than that for which the devices are rated.

For example an electric light bulb has a wire in it that at the given rated voltage will carry a current just large enough for the wire to get very hot (giving off light and heat), but not hot enough for it to melt. The amount of current in a circuit depends on the voltage supplied: if the voltage is too high, then the wire may melt and the light bulb would have "burned out". Similarly other electrical devices may stop working, or may even burst into flames if an overvoltage is delivered to the circuit of which these devices are part.

Sources[edit]

Natural[edit]

A typical natural source of transient overvoltage events is lightning. Bursts of solar wind following solar flares are also known to cause overvoltage in electrical circuits, especially onboard space satellites.

Man made[edit]

Man-made sources of spikes are usually caused by electromagnetic induction when switching on or off inductive loads (such as electric motors or electromagnets), or by switching heavy resistive AC loads when zero-crossing circuitry is not used - anywhere a large change of current takes place. One of the purposes of electromagnetic compatibility compliance is to eliminate such sources.

An important potential source of dangerous overvoltage is electronic warfare. There is intensive military research in this field, whose goal is to produce various transient electromagnetic devices designed to generate electromagnetic pulses that will disable an enemy's electronic equipment. A recent military development is that of the exploding capacitor designed to radiate a high voltage electromagnetic pulse. Another intense source of an electromagnetic pulse is a nuclear explosion.

Conduction path[edit]

The transient pulses can get into the equipment either by power or data lines, or directly through space from a strong electromagnetic field change - an electromagnetic pulse (EMP). Filters are used to prevent spikes entering or leaving the equipment through wires, and the devices coupled electromagnetically to space (such as radio-frequency pick-up coils in MRI scanners) are protected by shielding.

Overvoltage protection devices[edit]

arcing horns
avalanche diode
gas filled tube
lightning rod

Metal Oxide Varistor
SiBar Thyristor
spark gap
Transil
Trisil
Zener diode

External links[edit]

Overvoltage protection

English Journal

Microfluidic platform for environmental contaminants sensing and degradation based on boron-doped diamond electrodes.

Medina-Sánchez M, Mayorga-Martinez C, Watanabe T, Ivandini T, Honda Y, Pino F, Nakata K, Fujishima A, Einaga Y, Merkoçi A.
Biosensors & bioelectronics.Biosens Bioelectron.2016 Jan 15;75:365-74.
We have developed a lab-on-a-chip (LOC) platform for electrochemical detection and degradation of the pesticide atrazine (Atz). It is based on boron-doped diamond (BDD) electrodes and a competitive magneto-enzyme immunoassay (EIA) that enables high sensitivity. To detect the enzymatic reaction, we e
PMID 26339934

Formation of Li3O4 nano particles in the discharge products of non-aqueous lithium-oxygen batteries leads to lower charge overvoltage.

Shi L1, Xu A, Zhao TS.
Physical chemistry chemical physics : PCCP.Phys Chem Chem Phys.2015 Nov 28;17(44):29859-66. doi: 10.1039/c5cp03886c. Epub 2015 Oct 21.
Density functional theory calculations are made for bulk thermodynamic properties and surface energies of Li2O2, a primary discharge product, and Li3O4, a possible byproduct in the discharge products, of the non-aqueous lithium-oxygen batteries. Results show that the standard formation Gibbs free en
PMID 26486991

Reduction of charge and discharge polarization by cobalt nanoparticles-embedded carbon nanofibers for Li-O2 batteries.

Kim YJ1, Lee H1, Lee DJ1, Park JK2, Kim HT3.
ChemSusChem.ChemSusChem.2015 Aug 10;8(15):2496-502. doi: 10.1002/cssc.201500520. Epub 2015 Jul 14.
The problem of high charge polarization is one of the most significant challenges in current nonaqueous Li-O2 batteries. The development of an electrode for the oxygen evolution reaction (OER) at reduced overpotential is thus essential. Here, we suggest a binder-free electrode based on Co nanopartic
PMID 26178625

Japanese Journal

太陽光発電システムの架台に雷撃があった場合にパワーコンディショナのDC側で発生する渦電圧

山本和男,高見潤,岡部成光
電気学会論文誌. B, 電力・エネルギー部門誌 = The transactions of the Institute of Electrical Engineers of Japan. B, A publication of Power and Energy Society 132(11), 903-913, 2012-11-01
NAID 10031120089