On-Line
On-Line technology is identified with the abbreviation VFI (independent of voltage and frequency).
This technology is commonly called "Double Conversion".
In fact, during operation with the network present and suitable, the UPS output is powered by the combination of the rectifier which converts the UPS input voltage from alternating to direct and from the inverter which transforms this direct voltage into alternating.
This system ensures that the voltage present at the output of the entire UPS is perfectly sinusoidal, free of impurities and very stable both in voltage and in frequency linked to the problems present on the power supply.
Sorry for the inconvenience.