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ITGlossary · Power quality
Blackout
A complete and sudden loss of grid power, lasting anywhere from seconds to several hours.
Technical level:Basic
A total outage can last from a few seconds to several hours. Even a brief loss of voltage is enough to shut down computers and servers, lose unsaved data, corrupt files or halt a production process midway. Surges may also occur when power is restored.
A UPS takes over the load immediately: online models with no transfer time at all, line-interactive models within a few milliseconds. The battery has limits, however, so for long outages the UPS is combined with a generator.
Practical tip: connect the UPS to your servers via software or a network card, so that an automatic, orderly shutdown takes place before the battery runs out, even when nobody is present.
Related terms
- 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.
- Input Voltage WindowThe range of mains voltage within which a UPS keeps powering the load from the grid without switching to battery.
- OvervoltageA voltage above normal that lasts from seconds to hours and can stress or damage connected equipment.
- Harmonic DistortionDeviation of the waveform from a pure sine wave, caused mainly by non-linear loads such as power supplies and inverters.
- Noise (Electrical)Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
- Surge ProtectorA device that limits brief voltage spikes from lightning or grid switching by diverting the excess energy to earth.