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ITGlossary · Power quality
Input Voltage Window
The range of mains voltage within which a UPS keeps powering the load from the grid without switching to battery.
Technical level:Intermediate
Every UPS has a voltage range within which it supplies the load from the mains. If the voltage falls below the lower limit or rises above the upper one, it switches to battery. A line-interactive UPS with AVR typically accepts roughly 160–290 V, while many online UPS units also work at much lower voltages, usually with reduced load.
The wider the window, the fewer transfers to battery and the longer the battery lasts. This matters in rural and island areas, where voltage often sags at peak hours or in winter.
If you hear the UPS clicking often and switching to battery, measure the voltage at the socket. Many models let you adjust the sensitivity or the limits from the display or the software.
Related terms
- Voltage Regulation RangeThe input voltage range over which a UPS or stabilizer keeps its output close to 230 V without drawing on the battery.
- 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.
- 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.
- Voltage SpikeA momentary, very high voltage rise lasting microseconds, e.g. from lightning or load switching, that can damage equipment.
- BlackoutA complete and sudden loss of grid power, lasting anywhere from seconds to several hours.