Editing Surge protector (section)

== Protectors ==
[[File:Tricklestar Plug Strip.jpg|alt=|thumb|A [[power strip]] with built-in surge protector and multiple outlets]]

A transient surge protector attempts to limit the [[voltage]] supplied to an electric device by either blocking or [[short circuit|shorting]] current to reduce the voltage below a safe threshold. Blocking is done by using [[inductor]]s that inhibit a sudden change in current. Shorting is done by [[capacitor]]s which inhibit a sudden change in voltage or by [[spark gap]]s, [[discharge tube]]s, [[Zener effect]] semiconductors, and [[metal-oxide varistor]]s (MOVs), all of which begin to conduct current once a certain voltage threshold is reached.<ref>{{cite web |title=What is a Silicon Transient Voltage Suppressor... |url=http://www.element-14.com/community/docs/DOC-22401 |date=18 May 2010 |accessdate=23 September 2015 |work=element-14.com |archive-url=https://web.archive.org/web/20160220091139/https://www.element14.com/community/docs/DOC-22401 |archive-date=2016-02-20 |url-status=dead}}</ref> Some surge protectors use multiple elements.

In the shorting method, the electrical lines are temporarily shorted together (as by a spark gap) or clamped to a target voltage (as by a MOV), resulting in a large current flow. The voltage spike is reduced as the shorting current flows through the resistance in the power lines. The spike's energy is dissipated in the power lines or the [[Ground (electricity)|ground]], or in the protector, converted to heat. Since a spike lasts only tens of microseconds, the temperature rise is minimal. However, if the spike is large enough or long enough, the protector can be destroyed and power lines damaged.

Surge protectors for homes can be in [[power strip]]s used inside, or a device outside at the power panel. Sockets in a modern house use three wires: line, neutral and ground. Many protectors will connect between all three in pairs (line–neutral, line–ground and neutral–ground), because there are conditions, such as lightning, where both line and neutral have high voltage spikes that need to be shorted to ground.

Additionally, some consumer-grade protectors have ports for [[Ethernet]], [[cable television]] and [[plain old telephone service]], and plugging them in allows the surge protector to shield them from external electrical damage.<ref>{{cite news |last=Uysal |first=Ceren |url=https://interestingengineering.com/7-best-surge-protectors-to-keep-the-electricity-safe-running-around-your-house |title=7 best surge protectors to keep the electricity safe running around your house |work=Interesting Engineering |date=2022-06-13 |accessdate=2022-06-13 }}</ref>

The characteristic of a TVS requires that it respond to overvoltages faster than other common overvoltage protection components such as [[varistor]]s or [[gas discharge tube]]s. This makes TVS devices or components useful for protection against very fast and often damaging [[voltage spike]]s. These fast overvoltage spikes are present on all distribution networks and can be caused by either internal or external events, such as [[lightning]] or motor [[arcing]].<ref>{{cite web |title=Transient Voltage Suppressors (TVS) for Automot... |url=http://www.element-14.com/community/docs/DOC-22402 |accessdate=23 September 2015 |work=element-14.com}}</ref>

Applications of transient voltage suppression diodes are used for unidirectional or bidirectional [[electrostatic discharge]] protection of transmission or data lines in electronic circuits. MOV-based TVSs are used to protect home electronics and distribution systems and may accommodate industrial-level power distribution disturbances, saving downtime and damage to equipment. The level of energy in a transient overvoltage can be equated to energy measured in [[joule]]s or related to [[electric current]] when devices are rated for various applications. These bursts of overvoltage can be measured with specialized electronic meters that can show power disturbances of thousands of volts amplitude that last for a few microseconds or less.

It is possible for a MOV to overheat when exposed to overvoltage sufficient for the MOV to start conducting, but not enough to totally destroy it, or to blow a house fuse. If the overvoltage condition persists long enough to cause significant heating of the MOV, it can result in thermal damage to the device and potentially start a fire.<ref>{{cite web |title=metal oxide varistors – Circuit Breakers Blog – Expert Safety and Usage Information |url=http://www.circuitbreakersblog.com/tag/metal-oxide-varistors/ |accessdate=23 September 2015 |work=circuitbreakersblog.com}}</ref><ref>[http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING%20SURGE%20SUPPRESSOR%20FIRES.doc esdjournal.com].</ref>

===Comparison of transient suppressors===
{{sort under}}
{| class="wikitable sortable"
|-
! rowspan=2 class="unsortable" | Type
! colspan=2 | Surge capability (A)
! rowspan=2 class="unsortable" | Note
! rowspan=2 | Lifetime – number of surges
! rowspan=2 | Response time
! rowspan=2 | Shunt capacitance
! rowspan=2 | Leakage current (approximate)
|-
! Min
! Max

|-
|[[Resettable fuse]]
|2
|60
|SMD mountable
|infinite
|>1&nbsp;ms
|
|
|-
| [[Transient-voltage-suppression diode|TVS diode]]
| 1 
|15000
| [[Surface mount device|SMD]] to 15&nbsp;kA (large through-hole device)
| {{dunno}}
| ≈1&nbsp;ps (limited by pin lengths)
| <1&nbsp;pF (small surface-mount device) to >10&nbsp;nF (large through-hole device)
| 1&nbsp;μA
|-
| [[Metal-oxide varistor]] (MOV)
| 1
|70000
|
| @100&nbsp;A, 8{{times}}20&nbsp;μs pulse shape, 1,000 surges
| ≈1&nbsp;ns
| Typically 100–1,000&nbsp;pF
| 10&nbsp;μA
|-
| [[Avalanche diode]], [[Zener diode]]
| 50
|
|
| @50&nbsp;A, 8{{times}}20&nbsp;μs pulse shape, infinite
| <1&nbsp;μs
| 50&nbsp;pF
| 10&nbsp;μA
|-
| [[Gas discharge tube]]
| 20000
|
|
| @20&nbsp;kA, 8{{times}}20&nbsp;μs pulse width, >20 surges
| <5&nbsp;μs
| <1&nbsp;pF
| <1&nbsp;nA
|}