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ITGlossary · Power quality
Surge Protector
A device that limits brief voltage spikes from lightning or grid switching by diverting the excess energy to earth.
Technical level:Basic
Surge protection limits transient voltage spikes, caused by nearby lightning strikes or switching operations on the grid, by diverting the excess energy to earth. It comes as a surge protective device (SPD) in the electrical panel, as a protected power strip, or built into UPS units and stabilisers. It should not be confused with a lightning rod, which takes a direct strike on the building.
Surges last only an instant but can destroy power supplies, circuit boards and network cards. The most effective approach is layered: protection at the main panel plus additional protection close to sensitive equipment. Do not forget telephone lines and network cables.
Without proper earthing the protection does not work. Its components also wear out after strong surges, so check the status indicator and replace the unit when needed.
Related terms
- Voltage SpikeA momentary, very high voltage rise lasting microseconds, e.g. from lightning or load switching, that can damage equipment.
- Power ConditioningTechniques such as EMI/RFI filtering, surge protection and AVR that correct voltage problems before they reach the load.
- ATS (Automatic Transfer Switch)A device that automatically moves the load from the grid to a generator during an outage and back again when grid power returns.
- Automatic Voltage Regulator (AVR)A device that automatically maintains a constant voltage level to protect electrical equipment from fluctuations.
- Input Voltage WindowThe range of mains voltage within which a UPS keeps powering the load from the grid without switching to battery.
- IK Rating (Impact Protection)Scale from IK00 to IK10 under IEC 62262 that shows how much impact energy the enclosure of an electrical device can withstand.