FAQs - On-line UPS

On-line UPS information from single and three phase to monoblock and modular uninterruptible power supplies, battery runtimes, options and accessories.

An on-line double conversion UPS is a Voltage and Frequency Independent (VFI) uninterruptible power supply as defined by BS EN 62040. The inverter in this type of UPS produces a digitally generated sinewave output, supplied from a DC rectifier supply. The DC rectifier/converter supplies DC power to the inverter from the rectified mains power supply or the connected battery set.

The term ‘double-conversion’ online UPS refers to the conversion of mains power supply AC (alternating current) by the rectifier/converter to a DC (direct current) to supply the inverter and charge the battery set. The inverter section to which the load is always connected ‘inverts’ the DC to AC. The AC-DC-AC process is described as ‘double conversion’. There is also a Triple Conversion online UPS mode for some designs covering AC-DC-DC-AC where the DC-DC is a converter.

The inverter section of an double or triple conversion online uninterruptible power supply is designed for continuous running and the powering of the connected load. This features allows the UPS to be connected to battery extension packs for long runtime applications up to seven hours or more. Some smaller online UPS may be restricted to 4hours on battery at full load in order to protect the inverter electronics from heat damage.



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